From 5f2a71fcb7995633b335a1e380ac63a968e61320 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Sun, 15 Jan 2006 09:32:39 +0100 Subject: [PATCH] pcmcia: add pcmcia_disable_device pcmcia_disable_device(struct pcmcia_device *p_dev) performs the necessary cleanups upon device or driver removal: it calls the appropriate pcmcia_release_* functions, and can replace (most) of the current drivers' _release() functions. Signed-off-by: Dominik Brodowski --- Documentation/pcmcia/driver-changes.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation') diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt index 97420f08c786..c89a5e29bb4c 100644 --- a/Documentation/pcmcia/driver-changes.txt +++ b/Documentation/pcmcia/driver-changes.txt @@ -1,5 +1,11 @@ This file details changes in 2.6 which affect PCMCIA card driver authors: +* New release helper (as of 2.6.17) + Instead of calling pcmcia_release_{configuration,io,irq,win}, all that's + necessary now is calling pcmcia_disable_device. As there is no valid + reason left to call pcmcia_release_io and pcmcia_release_irq, they will + be removed soon. + * Unify detach and REMOVAL event code, as well as attach and INSERTION code (as of 2.6.16) void (*remove) (struct pcmcia_device *dev); -- cgit v1.2.2 From 50db3fdbbc98260fb538c1cc3f8cc597ba7bffe7 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Sun, 15 Jan 2006 10:05:19 +0100 Subject: [PATCH] pcmcia: convert remaining users of pcmcia_release_io and _irq Convert the remaining drivers which use pcmcia_release_io or pcmcia_release_irq, and remove the EXPORT of these symbols. Signed-off-by: Dominik Brodowski --- Documentation/pcmcia/driver-changes.txt | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt index c89a5e29bb4c..4739c5c3face 100644 --- a/Documentation/pcmcia/driver-changes.txt +++ b/Documentation/pcmcia/driver-changes.txt @@ -3,8 +3,8 @@ This file details changes in 2.6 which affect PCMCIA card driver authors: * New release helper (as of 2.6.17) Instead of calling pcmcia_release_{configuration,io,irq,win}, all that's necessary now is calling pcmcia_disable_device. As there is no valid - reason left to call pcmcia_release_io and pcmcia_release_irq, they will - be removed soon. + reason left to call pcmcia_release_io and pcmcia_release_irq, the + exports for them were removed. * Unify detach and REMOVAL event code, as well as attach and INSERTION code (as of 2.6.16) -- cgit v1.2.2 From d681518a56d25d21d73a421174d189242adc68c7 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Thu, 23 Mar 2006 16:06:23 +0100 Subject: [ALSA] Add support of LG LW20 laptop Add support of LG LW20 laptop with ALC880 codec (ALSA bug#1572). Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/ALSA-Configuration.txt | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 1def6049784c..baf18c6afdd6 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -701,6 +701,7 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. uniwill 3-jack F1734 2-jack lg LG laptop (m1 express dual) + lg-lw LG LW20 laptop test for testing/debugging purpose, almost all controls can be adjusted. Appearing only when compiled with $CONFIG_SND_DEBUG=y -- cgit v1.2.2 From 1841f613fd2e73f09d3fa2beeccf2f8d978ec2db Mon Sep 17 00:00:00 2001 From: Martin Langer Date: Mon, 27 Mar 2006 12:41:01 +0200 Subject: [ALSA] Add snd-miro driver Added snd-miro driver for miroSOUND PCM by Martin Langer. Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/ALSA-Configuration.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index baf18c6afdd6..1ac20940d8f9 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -1014,6 +1014,23 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. The power-management is supported. + Module snd-miro + --------------- + + Module for Miro soundcards: miroSOUND PCM 1 pro, + miroSOUND PCM 12, + miroSOUND PCM 20 Radio. + + port - Port # (0x530,0x604,0xe80,0xf40) + irq - IRQ # (5,7,9,10,11) + dma1 - 1st dma # (0,1,3) + dma2 - 2nd dma # (0,1) + mpu_port - MPU-401 port # (0x300,0x310,0x320,0x330) + mpu_irq - MPU-401 irq # (5,7,9,10) + fm_port - FM Port # (0x388) + wss - enable WSS mode + ide - enable onboard ide support + Module snd-mixart ----------------- -- cgit v1.2.2 From 109a9638f0fe38915838b7b9acd98e7cfa91797f Mon Sep 17 00:00:00 2001 From: Peter Gruber Date: Mon, 27 Mar 2006 13:10:28 +0200 Subject: [ALSA] Add snd-riptide driver for Conexant Riptide chip Add snd-riptide driver for Conexant Riptide chip by Peter Gruber. Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/ALSA-Configuration.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 1ac20940d8f9..5f79efa777a7 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -1220,6 +1220,20 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. The power-management is supported. + Module snd-riptide + ------------------ + + Module for Conexant Riptide chip + + joystick_port - Joystick port # (default: 0x200) + mpu_port - MPU401 port # (default: 0x330) + opl3_port - OPL3 port # (default: 0x388) + + This module supports multiple cards. + The driver requires the firmware loader support on kernel. + You need to install the firmware file "riptide.hex" to the standard + firmware path (e.g. /lib/firmware). + Module snd-rme32 ---------------- -- cgit v1.2.2 From b3a70d5ece60684c00d7d94ccc42741efdf99336 Mon Sep 17 00:00:00 2001 From: Ash Willis Date: Mon, 27 Mar 2006 13:20:40 +0200 Subject: [ALSA] Add snd-als300 driver for Avance Logic ALS300/ALS300+ soundcards Added snd-als300 driver for Avance Logic ALS300/ALS300+ soundcards by Ash Willis. Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/ALSA-Configuration.txt | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 5f79efa777a7..a8c3c7e847cf 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -190,6 +190,15 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. The power-management is supported. + Module snd-als300 + ----------------- + + Module for Avance Logic ALS300 and ALS300+ + + This module supports multiple cards. + + The power-management is supported. + Module snd-als4000 ------------------ -- cgit v1.2.2 From cf40a310a7aaf1944eea3e01e9c120b31850c3b6 Mon Sep 17 00:00:00 2001 From: Rene Herman Date: Tue, 28 Mar 2006 12:38:20 +0200 Subject: [ALSA] AdLib FM card driver Attached you'll find an ALSA driver for AdLib FM cards. An AdLib card is just an OPL2, which was already supported by sound/drivers/opl3, so only very minimal bus-glue is needed. The patch applies cleanly to both 2.6.16 and 2.6.16-mm1. The driver has been tested with an actual ancient 8-bit ISA AdLib card and works fine. It also works fine for an OPL3 {,emulation} as still found on many ISA soundcards but given that AdLib cards don't have their own mixer, upping the volume from 0 might be a problem without the card driver already loaded and driving the OPL3. Signed-off-by: Takashi Iwai --- Documentation/sound/alsa/ALSA-Configuration.txt | 28 +++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index a8c3c7e847cf..0ee2c7dfc482 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -120,6 +120,34 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. enable - enable card - Default: enabled, for PCI and ISA PnP cards + Module snd-adlib + ---------------- + + Module for AdLib FM cards. + + port - port # for OPL chip + + This module supports multiple cards. It does not support autoprobe, so + the port must be specified. For actual AdLib FM cards it will be 0x388. + Note that this card does not have PCM support and no mixer; only FM + synthesis. + + Make sure you have "sbiload" from the alsa-tools package available and, + after loading the module, find out the assigned ALSA sequencer port + number through "sbiload -l". Example output: + + Port Client name Port name + 64:0 OPL2 FM synth OPL2 FM Port + + Load the std.sb and drums.sb patches also supplied by sbiload: + + sbiload -p 64:0 std.sb drums.sb + + If you use this driver to drive an OPL3, you can use std.o3 and drums.o3 + instead. To have the card produce sound, use aplaymidi from alsa-utils: + + aplaymidi -p 64:0 foo.mid + Module snd-ad1816a ------------------ -- cgit v1.2.2 From 93fac7041f082297b93655a0e49f659cd7520e40 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Fri, 31 Mar 2006 02:29:56 -0800 Subject: [PATCH] mm: schedule find_trylock_page() removal find_trylock_page() is an odd interface in that it doesn't take a reference like the others. Now that XFS no longer uses it, and its last remaining caller actually wants an elevated refcount, opencode that callsite and schedule find_trylock_page() for removal. Signed-off-by: Nick Piggin Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/feature-removal-schedule.txt | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation') diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 495858b236b6..a92b10bb0b03 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -241,3 +241,15 @@ Why: The USB subsystem has changed a lot over time, and it has been Who: Greg Kroah-Hartman --------------------------- + +What: find_trylock_page +When: January 2007 +Why: The interface no longer has any callers left in the kernel. It + is an odd interface (compared with other find_*_page functions), in + that it does not take a refcount to the page, only the page lock. + It should be replaced with find_get_page or find_lock_page if possible. + This feature removal can be reevaluated if users of the interface + cannot cleanly use something else. +Who: Nick Piggin + +--------------------------- -- cgit v1.2.2 From 75c1d31d9ea71025b73430c696b727e8aa15872d Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Fri, 31 Mar 2006 02:31:03 -0800 Subject: [PATCH] LED: class documentation The LED class/subsystem takes John Lenz's work and extends and alters it to give what I think should be a fairly universal LED implementation. The series consists of several logical units: * LED Core + Class implementation * LED Trigger Core implementation * LED timer trigger (example of a complex trigger) * LED device drivers for corgi, spitz and tosa Zaurus models * LED device driver for locomo LEDs * LED device driver for ARM ixp4xx LEDs * Zaurus charging LED trigger * IDE disk activity LED trigger * NAND MTD activity LED trigger Why? ==== LEDs are really simple devices usually amounting to a GPIO that can be turned on and off so why do we need all this code? On handheld or embedded devices they're an important part of an often limited user interface. Both users and developers want to be able to control and configure what the LED does and the number of different things they'd potentially want the LED to show is large. A subsystem is needed to try and provide all this different functionality in an architecture independent, simple but complete, generic and scalable manner. The alternative is for everyone to implement just what they need hidden away in different corners of the kernel source tree and to provide an inconsistent interface to userspace. Other Implementations ===================== I'm aware of the existing arm led implementation. Currently the new subsystem and the arm code can coexist quite happily. Its up to the arm community to decide whether this new interface is acceptable to them. As far as I can see, the new interface can do everything the existing arm implementation can with the advantage that the new code is architecture independent and much more generic, configurable and scalable. I'm prepared to make the conversion to the LED subsystem (or assist with it) if appropriate. Implementation Details ====================== I've stripped a lot of code out of John's original LED class. Colours were removed as LED colour is now part of the device name. Multiple colours are to be handled as multiple led devices. This means you get full control over each colour. I also removed the LED hardware timer code as the generic timer isn't going to add much overhead and is just as useful. I also decided to have the LED core track the current LED status (to ease suspend/resume handling) removing the need for brightness_get implementations in the LED drivers. An underlying design philosophy is simplicity. The aim is to keep a small amount of code giving as much functionality as possible. The major new idea is the led "trigger". A trigger is a source of led events. Triggers can either be simple or complex. A simple trigger isn't configurable and is designed to slot into existing subsystems with minimal additional code. Examples are the ide-disk, nand-disk and zaurus-charging triggers. With leds disabled, the code optimises away. Examples are nand-disk and ide-disk. Complex triggers whilst available to all LEDs have LED specific parameters and work on a per LED basis. The timer trigger is an example. You can change triggers in a similar manner to the way an IO scheduler is chosen (via /sys/class/leds/somedevice/trigger). So far there are only a handful of examples but it should easy to add further LED triggers without too much interference into other subsystems. Known Issues ============ The LED Trigger core cannot be a module as the simple trigger functions would cause nightmare dependency issues. I see this as a minor issue compared to the benefits the simple trigger functionality brings. The rest of the LED subsystem can be modular. Some leds can be programmed to flash in hardware. As this isn't a generic LED device property, I think this should be exported as a device specific sysfs attribute rather than part of the class if this functionality is required (eg. to keep the led flashing whilst the device is suspended). Future Development ================== At the moment, a trigger can't be created specifically for a single LED. There are a number of cases where a trigger might only be mappable to a particular LED. The addition of triggers provided by the LED driver should cover this option and be possible to add without breaking the current interface. A CPU activity trigger similar to that found in the arm led implementation should be trivial to add. This patch: Add some brief documentation of the design decisions behind the LED class and how it appears to users. Signed-off-by: Richard Purdie Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/leds-class.txt | 71 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 Documentation/leds-class.txt (limited to 'Documentation') diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt new file mode 100644 index 000000000000..8c35c0426110 --- /dev/null +++ b/Documentation/leds-class.txt @@ -0,0 +1,71 @@ +LED handling under Linux +======================== + +If you're reading this and thinking about keyboard leds, these are +handled by the input subsystem and the led class is *not* needed. + +In its simplest form, the LED class just allows control of LEDs from +userspace. LEDs appear in /sys/class/leds/. The brightness file will +set the brightness of the LED (taking a value 0-255). Most LEDs don't +have hardware brightness support so will just be turned on for non-zero +brightness settings. + +The class also introduces the optional concept of an LED trigger. A trigger +is a kernel based source of led events. Triggers can either be simple or +complex. A simple trigger isn't configurable and is designed to slot into +existing subsystems with minimal additional code. Examples are the ide-disk, +nand-disk and sharpsl-charge triggers. With led triggers disabled, the code +optimises away. + +Complex triggers whilst available to all LEDs have LED specific +parameters and work on a per LED basis. The timer trigger is an example. + +You can change triggers in a similar manner to the way an IO scheduler +is chosen (via /sys/class/leds//trigger). Trigger specific +parameters can appear in /sys/class/leds/ once a given trigger is +selected. + + +Design Philosophy +================= + +The underlying design philosophy is simplicity. LEDs are simple devices +and the aim is to keep a small amount of code giving as much functionality +as possible. Please keep this in mind when suggesting enhancements. + + +LED Device Naming +================= + +Is currently of the form: + +"devicename:colour" + +There have been calls for LED properties such as colour to be exported as +individual led class attributes. As a solution which doesn't incur as much +overhead, I suggest these become part of the device name. The naming scheme +above leaves scope for further attributes should they be needed. + + +Known Issues +============ + +The LED Trigger core cannot be a module as the simple trigger functions +would cause nightmare dependency issues. I see this as a minor issue +compared to the benefits the simple trigger functionality brings. The +rest of the LED subsystem can be modular. + +Some leds can be programmed to flash in hardware. As this isn't a generic +LED device property, this should be exported as a device specific sysfs +attribute rather than part of the class if this functionality is required. + + +Future Development +================== + +At the moment, a trigger can't be created specifically for a single LED. +There are a number of cases where a trigger might only be mappable to a +particular LED (ACPI?). The addition of triggers provided by the LED driver +should cover this option and be possible to add without breaking the +current interface. + -- cgit v1.2.2 From a244e1698ae3609cdfe24088e1293593cb7a5278 Mon Sep 17 00:00:00 2001 From: Adrian Bunk Date: Fri, 31 Mar 2006 02:32:11 -0800 Subject: [PATCH] fs/namei.c: make lookup_hash() static As announced, lookup_hash() can now become static. Signed-off-by: Adrian Bunk Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/feature-removal-schedule.txt | 7 ------- 1 file changed, 7 deletions(-) (limited to 'Documentation') diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index a92b10bb0b03..59d0c74c79c9 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -127,13 +127,6 @@ Who: Christoph Hellwig --------------------------- -What: EXPORT_SYMBOL(lookup_hash) -When: January 2006 -Why: Too low-level interface. Use lookup_one_len or lookup_create instead. -Who: Christoph Hellwig - ---------------------------- - What: CONFIG_FORCED_INLINING When: June 2006 Why: Config option is there to see if gcc is good enough. (in january -- cgit v1.2.2 From 108b42b4b966462444265806e3d7260a632ad630 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 31 Mar 2006 16:00:29 +0100 Subject: [PATCH] Document Linux's memory barriers [try #7] The attached patch documents the Linux kernel's memory barriers. I've updated it from the comments I've been given. The per-arch notes sections are gone because it's clear that there are so many exceptions, that it's not worth having them. I've added a list of references to other documents. I've tried to get rid of the concept of memory accesses appearing on the bus; what matters is apparent behaviour with respect to other observers in the system. Interrupts barrier effects are now considered to be non-existent. They may be there, but you may not rely on them. I've added a couple of definition sections at the top of the document: one to specify the minimum execution model that may be assumed, the other to specify what this document refers to by the term "memory". I've made greater mention of the use of mmiowb(). I've adjusted the way in which caches are described, and described the fun that can be had with cache coherence maintenance being unordered and data dependency not being necessarily implicit. I've described (smp_)read_barrier_depends(). I've rearranged the order of the sections, so that memory barriers are discussed in abstract first, and then described the memory barrier facilities available on Linux, before going on to more real-world discussions and examples. I've added information about the lack of memory barriering effects with atomic ops and bitops. I've added information about control dependencies. I've added more diagrams to illustrate caching interactions between CPUs. Signed-off-by: David Howells Signed-off-by: Linus Torvalds --- Documentation/memory-barriers.txt | 1913 +++++++++++++++++++++++++++++++++++++ 1 file changed, 1913 insertions(+) create mode 100644 Documentation/memory-barriers.txt (limited to 'Documentation') diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt new file mode 100644 index 000000000000..f8550310a6d5 --- /dev/null +++ b/Documentation/memory-barriers.txt @@ -0,0 +1,1913 @@ + ============================ + LINUX KERNEL MEMORY BARRIERS + ============================ + +By: David Howells + +Contents: + + (*) Abstract memory access model. + + - Device operations. + - Guarantees. + + (*) What are memory barriers? + + - Varieties of memory barrier. + - What may not be assumed about memory barriers? + - Data dependency barriers. + - Control dependencies. + - SMP barrier pairing. + - Examples of memory barrier sequences. + + (*) Explicit kernel barriers. + + - Compiler barrier. + - The CPU memory barriers. + - MMIO write barrier. + + (*) Implicit kernel memory barriers. + + - Locking functions. + - Interrupt disabling functions. + - Miscellaneous functions. + + (*) Inter-CPU locking barrier effects. + + - Locks vs memory accesses. + - Locks vs I/O accesses. + + (*) Where are memory barriers needed? + + - Interprocessor interaction. + - Atomic operations. + - Accessing devices. + - Interrupts. + + (*) Kernel I/O barrier effects. + + (*) Assumed minimum execution ordering model. + + (*) The effects of the cpu cache. + + - Cache coherency. + - Cache coherency vs DMA. + - Cache coherency vs MMIO. + + (*) The things CPUs get up to. + + - And then there's the Alpha. + + (*) References. + + +============================ +ABSTRACT MEMORY ACCESS MODEL +============================ + +Consider the following abstract model of the system: + + : : + : : + : : + +-------+ : +--------+ : +-------+ + | | : | | : | | + | | : | | : | | + | CPU 1 |<----->| Memory |<----->| CPU 2 | + | | : | | : | | + | | : | | : | | + +-------+ : +--------+ : +-------+ + ^ : ^ : ^ + | : | : | + | : | : | + | : v : | + | : +--------+ : | + | : | | : | + | : | | : | + +---------->| Device |<----------+ + : | | : + : | | : + : +--------+ : + : : + +Each CPU executes a program that generates memory access operations. In the +abstract CPU, memory operation ordering is very relaxed, and a CPU may actually +perform the memory operations in any order it likes, provided program causality +appears to be maintained. Similarly, the compiler may also arrange the +instructions it emits in any order it likes, provided it doesn't affect the +apparent operation of the program. + +So in the above diagram, the effects of the memory operations performed by a +CPU are perceived by the rest of the system as the operations cross the +interface between the CPU and rest of the system (the dotted lines). + + +For example, consider the following sequence of events: + + CPU 1 CPU 2 + =============== =============== + { A == 1; B == 2 } + A = 3; x = A; + B = 4; y = B; + +The set of accesses as seen by the memory system in the middle can be arranged +in 24 different combinations: + + STORE A=3, STORE B=4, x=LOAD A->3, y=LOAD B->4 + STORE A=3, STORE B=4, y=LOAD B->4, x=LOAD A->3 + STORE A=3, x=LOAD A->3, STORE B=4, y=LOAD B->4 + STORE A=3, x=LOAD A->3, y=LOAD B->2, STORE B=4 + STORE A=3, y=LOAD B->2, STORE B=4, x=LOAD A->3 + STORE A=3, y=LOAD B->2, x=LOAD A->3, STORE B=4 + STORE B=4, STORE A=3, x=LOAD A->3, y=LOAD B->4 + STORE B=4, ... + ... + +and can thus result in four different combinations of values: + + x == 1, y == 2 + x == 1, y == 4 + x == 3, y == 2 + x == 3, y == 4 + + +Furthermore, the stores committed by a CPU to the memory system may not be +perceived by the loads made by another CPU in the same order as the stores were +committed. + + +As a further example, consider this sequence of events: + + CPU 1 CPU 2 + =============== =============== + { A == 1, B == 2, C = 3, P == &A, Q == &C } + B = 4; Q = P; + P = &B D = *Q; + +There is an obvious data dependency here, as the value loaded into D depends on +the address retrieved from P by CPU 2. At the end of the sequence, any of the +following results are possible: + + (Q == &A) and (D == 1) + (Q == &B) and (D == 2) + (Q == &B) and (D == 4) + +Note that CPU 2 will never try and load C into D because the CPU will load P +into Q before issuing the load of *Q. + + +DEVICE OPERATIONS +----------------- + +Some devices present their control interfaces as collections of memory +locations, but the order in which the control registers are accessed is very +important. For instance, imagine an ethernet card with a set of internal +registers that are accessed through an address port register (A) and a data +port register (D). To read internal register 5, the following code might then +be used: + + *A = 5; + x = *D; + +but this might show up as either of the following two sequences: + + STORE *A = 5, x = LOAD *D + x = LOAD *D, STORE *A = 5 + +the second of which will almost certainly result in a malfunction, since it set +the address _after_ attempting to read the register. + + +GUARANTEES +---------- + +There are some minimal guarantees that may be expected of a CPU: + + (*) On any given CPU, dependent memory accesses will be issued in order, with + respect to itself. This means that for: + + Q = P; D = *Q; + + the CPU will issue the following memory operations: + + Q = LOAD P, D = LOAD *Q + + and always in that order. + + (*) Overlapping loads and stores within a particular CPU will appear to be + ordered within that CPU. This means that for: + + a = *X; *X = b; + + the CPU will only issue the following sequence of memory operations: + + a = LOAD *X, STORE *X = b + + And for: + + *X = c; d = *X; + + the CPU will only issue: + + STORE *X = c, d = LOAD *X + + (Loads and stores overlap if they are targetted at overlapping pieces of + memory). + +And there are a number of things that _must_ or _must_not_ be assumed: + + (*) It _must_not_ be assumed that independent loads and stores will be issued + in the order given. This means that for: + + X = *A; Y = *B; *D = Z; + + we may get any of the following sequences: + + X = LOAD *A, Y = LOAD *B, STORE *D = Z + X = LOAD *A, STORE *D = Z, Y = LOAD *B + Y = LOAD *B, X = LOAD *A, STORE *D = Z + Y = LOAD *B, STORE *D = Z, X = LOAD *A + STORE *D = Z, X = LOAD *A, Y = LOAD *B + STORE *D = Z, Y = LOAD *B, X = LOAD *A + + (*) It _must_ be assumed that overlapping memory accesses may be merged or + discarded. This means that for: + + X = *A; Y = *(A + 4); + + we may get any one of the following sequences: + + X = LOAD *A; Y = LOAD *(A + 4); + Y = LOAD *(A + 4); X = LOAD *A; + {X, Y} = LOAD {*A, *(A + 4) }; + + And for: + + *A = X; Y = *A; + + we may get either of: + + STORE *A = X; Y = LOAD *A; + STORE *A = Y; + + +========================= +WHAT ARE MEMORY BARRIERS? +========================= + +As can be seen above, independent memory operations are effectively performed +in random order, but this can be a problem for CPU-CPU interaction and for I/O. +What is required is some way of intervening to instruct the compiler and the +CPU to restrict the order. + +Memory barriers are such interventions. They impose a perceived partial +ordering between the memory operations specified on either side of the barrier. +They request that the sequence of memory events generated appears to other +parts of the system as if the barrier is effective on that CPU. + + +VARIETIES OF MEMORY BARRIER +--------------------------- + +Memory barriers come in four basic varieties: + + (1) Write (or store) memory barriers. + + A write memory barrier gives a guarantee that all the STORE operations + specified before the barrier will appear to happen before all the STORE + operations specified after the barrier with respect to the other + components of the system. + + A write barrier is a partial ordering on stores only; it is not required + to have any effect on loads. + + A CPU can be viewed as as commiting a sequence of store operations to the + memory system as time progresses. All stores before a write barrier will + occur in the sequence _before_ all the stores after the write barrier. + + [!] Note that write barriers should normally be paired with read or data + dependency barriers; see the "SMP barrier pairing" subsection. + + + (2) Data dependency barriers. + + A data dependency barrier is a weaker form of read barrier. In the case + where two loads are performed such that the second depends on the result + of the first (eg: the first load retrieves the address to which the second + load will be directed), a data dependency barrier would be required to + make sure that the target of the second load is updated before the address + obtained by the first load is accessed. + + A data dependency barrier is a partial ordering on interdependent loads + only; it is not required to have any effect on stores, independent loads + or overlapping loads. + + As mentioned in (1), the other CPUs in the system can be viewed as + committing sequences of stores to the memory system that the CPU being + considered can then perceive. A data dependency barrier issued by the CPU + under consideration guarantees that for any load preceding it, if that + load touches one of a sequence of stores from another CPU, then by the + time the barrier completes, the effects of all the stores prior to that + touched by the load will be perceptible to any loads issued after the data + dependency barrier. + + See the "Examples of memory barrier sequences" subsection for diagrams + showing the ordering constraints. + + [!] Note that the first load really has to have a _data_ dependency and + not a control dependency. If the address for the second load is dependent + on the first load, but the dependency is through a conditional rather than + actually loading the address itself, then it's a _control_ dependency and + a full read barrier or better is required. See the "Control dependencies" + subsection for more information. + + [!] Note that data dependency barriers should normally be paired with + write barriers; see the "SMP barrier pairing" subsection. + + + (3) Read (or load) memory barriers. + + A read barrier is a data dependency barrier plus a guarantee that all the + LOAD operations specified before the barrier will appear to happen before + all the LOAD operations specified after the barrier with respect to the + other components of the system. + + A read barrier is a partial ordering on loads only; it is not required to + have any effect on stores. + + Read memory barriers imply data dependency barriers, and so can substitute + for them. + + [!] Note that read barriers should normally be paired with write barriers; + see the "SMP barrier pairing" subsection. + + + (4) General memory barriers. + + A general memory barrier is a combination of both a read memory barrier + and a write memory barrier. It is a partial ordering over both loads and + stores. + + General memory barriers imply both read and write memory barriers, and so + can substitute for either. + + +And a couple of implicit varieties: + + (5) LOCK operations. + + This acts as a one-way permeable barrier. It guarantees that all memory + operations after the LOCK operation will appear to happen after the LOCK + operation with respect to the other components of the system. + + Memory operations that occur before a LOCK operation may appear to happen + after it completes. + + A LOCK operation should almost always be paired with an UNLOCK operation. + + + (6) UNLOCK operations. + + This also acts as a one-way permeable barrier. It guarantees that all + memory operations before the UNLOCK operation will appear to happen before + the UNLOCK operation with respect to the other components of the system. + + Memory operations that occur after an UNLOCK operation may appear to + happen before it completes. + + LOCK and UNLOCK operations are guaranteed to appear with respect to each + other strictly in the order specified. + + The use of LOCK and UNLOCK operations generally precludes the need for + other sorts of memory barrier (but note the exceptions mentioned in the + subsection "MMIO write barrier"). + + +Memory barriers are only required where there's a possibility of interaction +between two CPUs or between a CPU and a device. If it can be guaranteed that +there won't be any such interaction in any particular piece of code, then +memory barriers are unnecessary in that piece of code. + + +Note that these are the _minimum_ guarantees. Different architectures may give +more substantial guarantees, but they may _not_ be relied upon outside of arch +specific code. + + +WHAT MAY NOT BE ASSUMED ABOUT MEMORY BARRIERS? +---------------------------------------------- + +There are certain things that the Linux kernel memory barriers do not guarantee: + + (*) There is no guarantee that any of the memory accesses specified before a + memory barrier will be _complete_ by the completion of a memory barrier + instruction; the barrier can be considered to draw a line in that CPU's + access queue that accesses of the appropriate type may not cross. + + (*) There is no guarantee that issuing a memory barrier on one CPU will have + any direct effect on another CPU or any other hardware in the system. The + indirect effect will be the order in which the second CPU sees the effects + of the first CPU's accesses occur, but see the next point: + + (*) There is no guarantee that the a CPU will see the correct order of effects + from a second CPU's accesses, even _if_ the second CPU uses a memory + barrier, unless the first CPU _also_ uses a matching memory barrier (see + the subsection on "SMP Barrier Pairing"). + + (*) There is no guarantee that some intervening piece of off-the-CPU + hardware[*] will not reorder the memory accesses. CPU cache coherency + mechanisms should propagate the indirect effects of a memory barrier + between CPUs, but might not do so in order. + + [*] For information on bus mastering DMA and coherency please read: + + Documentation/pci.txt + Documentation/DMA-mapping.txt + Documentation/DMA-API.txt + + +DATA DEPENDENCY BARRIERS +------------------------ + +The usage requirements of data dependency barriers are a little subtle, and +it's not always obvious that they're needed. To illustrate, consider the +following sequence of events: + + CPU 1 CPU 2 + =============== =============== + { A == 1, B == 2, C = 3, P == &A, Q == &C } + B = 4; + + P = &B + Q = P; + D = *Q; + +There's a clear data dependency here, and it would seem that by the end of the +sequence, Q must be either &A or &B, and that: + + (Q == &A) implies (D == 1) + (Q == &B) implies (D == 4) + +But! CPU 2's perception of P may be updated _before_ its perception of B, thus +leading to the following situation: + + (Q == &B) and (D == 2) ???? + +Whilst this may seem like a failure of coherency or causality maintenance, it +isn't, and this behaviour can be observed on certain real CPUs (such as the DEC +Alpha). + +To deal with this, a data dependency barrier must be inserted between the +address load and the data load: + + CPU 1 CPU 2 + =============== =============== + { A == 1, B == 2, C = 3, P == &A, Q == &C } + B = 4; + + P = &B + Q = P; + + D = *Q; + +This enforces the occurrence of one of the two implications, and prevents the +third possibility from arising. + +[!] Note that this extremely counterintuitive situation arises most easily on +machines with split caches, so that, for example, one cache bank processes +even-numbered cache lines and the other bank processes odd-numbered cache +lines. The pointer P might be stored in an odd-numbered cache line, and the +variable B might be stored in an even-numbered cache line. Then, if the +even-numbered bank of the reading CPU's cache is extremely busy while the +odd-numbered bank is idle, one can see the new value of the pointer P (&B), +but the old value of the variable B (1). + + +Another example of where data dependency barriers might by required is where a +number is read from memory and then used to calculate the index for an array +access: + + CPU 1 CPU 2 + =============== =============== + { M[0] == 1, M[1] == 2, M[3] = 3, P == 0, Q == 3 } + M[1] = 4; + + P = 1 + Q = P; + + D = M[Q]; + + +The data dependency barrier is very important to the RCU system, for example. +See rcu_dereference() in include/linux/rcupdate.h. This permits the current +target of an RCU'd pointer to be replaced with a new modified target, without +the replacement target appearing to be incompletely initialised. + +See also the subsection on "Cache Coherency" for a more thorough example. + + +CONTROL DEPENDENCIES +-------------------- + +A control dependency requires a full read memory barrier, not simply a data +dependency barrier to make it work correctly. Consider the following bit of +code: + + q = &a; + if (p) + q = &b; + + x = *q; + +This will not have the desired effect because there is no actual data +dependency, but rather a control dependency that the CPU may short-circuit by +attempting to predict the outcome in advance. In such a case what's actually +required is: + + q = &a; + if (p) + q = &b; + + x = *q; + + +SMP BARRIER PAIRING +------------------- + +When dealing with CPU-CPU interactions, certain types of memory barrier should +always be paired. A lack of appropriate pairing is almost certainly an error. + +A write barrier should always be paired with a data dependency barrier or read +barrier, though a general barrier would also be viable. Similarly a read +barrier or a data dependency barrier should always be paired with at least an +write barrier, though, again, a general barrier is viable: + + CPU 1 CPU 2 + =============== =============== + a = 1; + + b = 2; x = a; + + y = b; + +Or: + + CPU 1 CPU 2 + =============== =============================== + a = 1; + + b = &a; x = b; + + y = *x; + +Basically, the read barrier always has to be there, even though it can be of +the "weaker" type. + + +EXAMPLES OF MEMORY BARRIER SEQUENCES +------------------------------------ + +Firstly, write barriers act as a partial orderings on store operations. +Consider the following sequence of events: + + CPU 1 + ======================= + STORE A = 1 + STORE B = 2 + STORE C = 3 + + STORE D = 4 + STORE E = 5 + +This sequence of events is committed to the memory coherence system in an order +that the rest of the system might perceive as the unordered set of { STORE A, +STORE B, STORE C } all occuring before the unordered set of { STORE D, STORE E +}: + + +-------+ : : + | | +------+ + | |------>| C=3 | } /\ + | | : +------+ }----- \ -----> Events perceptible + | | : | A=1 | } \/ to rest of system + | | : +------+ } + | CPU 1 | : | B=2 | } + | | +------+ } + | | wwwwwwwwwwwwwwww } <--- At this point the write barrier + | | +------+ } requires all stores prior to the + | | : | E=5 | } barrier to be committed before + | | : +------+ } further stores may be take place. + | |------>| D=4 | } + | | +------+ + +-------+ : : + | + | Sequence in which stores committed to memory system + | by CPU 1 + V + + +Secondly, data dependency barriers act as a partial orderings on data-dependent +loads. Consider the following sequence of events: + + CPU 1 CPU 2 + ======================= ======================= + STORE A = 1 + STORE B = 2 + + STORE C = &B LOAD X + STORE D = 4 LOAD C (gets &B) + LOAD *C (reads B) + +Without intervention, CPU 2 may perceive the events on CPU 1 in some +effectively random order, despite the write barrier issued by CPU 1: + + +-------+ : : : : + | | +------+ +-------+ | Sequence of update + | |------>| B=2 |----- --->| Y->8 | | of perception on + | | : +------+ \ +-------+ | CPU 2 + | CPU 1 | : | A=1 | \ --->| C->&Y | V + | | +------+ | +-------+ + | | wwwwwwwwwwwwwwww | : : + | | +------+ | : : + | | : | C=&B |--- | : : +-------+ + | | : +------+ \ | +-------+ | | + | |------>| D=4 | ----------->| C->&B |------>| | + | | +------+ | +-------+ | | + +-------+ : : | : : | | + | : : | | + | : : | CPU 2 | + | +-------+ | | + Apparently incorrect ---> | | B->7 |------>| | + perception of B (!) | +-------+ | | + | : : | | + | +-------+ | | + The load of X holds ---> \ | X->9 |------>| | + up the maintenance \ +-------+ | | + of coherence of B ----->| B->2 | +-------+ + +-------+ + : : + + +In the above example, CPU 2 perceives that B is 7, despite the load of *C +(which would be B) coming after the the LOAD of C. + +If, however, a data dependency barrier were to be placed between the load of C +and the load of *C (ie: B) on CPU 2, then the following will occur: + + +-------+ : : : : + | | +------+ +-------+ + | |------>| B=2 |----- --->| Y->8 | + | | : +------+ \ +-------+ + | CPU 1 | : | A=1 | \ --->| C->&Y | + | | +------+ | +-------+ + | | wwwwwwwwwwwwwwww | : : + | | +------+ | : : + | | : | C=&B |--- | : : +-------+ + | | : +------+ \ | +-------+ | | + | |------>| D=4 | ----------->| C->&B |------>| | + | | +------+ | +-------+ | | + +-------+ : : | : : | | + | : : | | + | : : | CPU 2 | + | +-------+ | | + \ | X->9 |------>| | + \ +-------+ | | + ----->| B->2 | | | + +-------+ | | + Makes sure all effects ---> ddddddddddddddddd | | + prior to the store of C +-------+ | | + are perceptible to | B->2 |------>| | + successive loads +-------+ | | + : : +-------+ + + +And thirdly, a read barrier acts as a partial order on loads. Consider the +following sequence of events: + + CPU 1 CPU 2 + ======================= ======================= + STORE A=1 + STORE B=2 + STORE C=3 + + STORE D=4 + STORE E=5 + LOAD A + LOAD B + LOAD C + LOAD D + LOAD E + +Without intervention, CPU 2 may then choose to perceive the events on CPU 1 in +some effectively random order, despite the write barrier issued by CPU 1: + + +-------+ : : + | | +------+ + | |------>| C=3 | } + | | : +------+ } + | | : | A=1 | } + | | : +------+ } + | CPU 1 | : | B=2 | }--- + | | +------+ } \ + | | wwwwwwwwwwwww} \ + | | +------+ } \ : : +-------+ + | | : | E=5 | } \ +-------+ | | + | | : +------+ } \ { | C->3 |------>| | + | |------>| D=4 | } \ { +-------+ : | | + | | +------+ \ { | E->5 | : | | + +-------+ : : \ { +-------+ : | | + Transfer -->{ | A->1 | : | CPU 2 | + from CPU 1 { +-------+ : | | + to CPU 2 { | D->4 | : | | + { +-------+ : | | + { | B->2 |------>| | + +-------+ | | + : : +-------+ + + +If, however, a read barrier were to be placed between the load of C and the +load of D on CPU 2, then the partial ordering imposed by CPU 1 will be +perceived correctly by CPU 2. + + +-------+ : : + | | +------+ + | |------>| C=3 | } + | | : +------+ } + | | : | A=1 | }--- + | | : +------+ } \ + | CPU 1 | : | B=2 | } \ + | | +------+ \ + | | wwwwwwwwwwwwwwww \ + | | +------+ \ : : +-------+ + | | : | E=5 | } \ +-------+ | | + | | : +------+ }--- \ { | C->3 |------>| | + | |------>| D=4 | } \ \ { +-------+ : | | + | | +------+ \ -->{ | B->2 | : | | + +-------+ : : \ { +-------+ : | | + \ { | A->1 | : | CPU 2 | + \ +-------+ | | + At this point the read ----> \ rrrrrrrrrrrrrrrrr | | + barrier causes all effects \ +-------+ | | + prior to the storage of C \ { | E->5 | : | | + to be perceptible to CPU 2 -->{ +-------+ : | | + { | D->4 |------>| | + +-------+ | | + : : +-------+ + + +======================== +EXPLICIT KERNEL BARRIERS +======================== + +The Linux kernel has a variety of different barriers that act at different +levels: + + (*) Compiler barrier. + + (*) CPU memory barriers. + + (*) MMIO write barrier. + + +COMPILER BARRIER +---------------- + +The Linux kernel has an explicit compiler barrier function that prevents the +compiler from moving the memory accesses either side of it to the other side: + + barrier(); + +This a general barrier - lesser varieties of compiler barrier do not exist. + +The compiler barrier has no direct effect on the CPU, which may then reorder +things however it wishes. + + +CPU MEMORY BARRIERS +------------------- + +The Linux kernel has eight basic CPU memory barriers: + + TYPE MANDATORY SMP CONDITIONAL + =============== ======================= =========================== + GENERAL mb() smp_mb() + WRITE wmb() smp_wmb() + READ rmb() smp_rmb() + DATA DEPENDENCY read_barrier_depends() smp_read_barrier_depends() + + +All CPU memory barriers unconditionally imply compiler barriers. + +SMP memory barriers are reduced to compiler barriers on uniprocessor compiled +systems because it is assumed that a CPU will be appear to be self-consistent, +and will order overlapping accesses correctly with respect to itself. + +[!] Note that SMP memory barriers _must_ be used to control the ordering of +references to shared memory on SMP systems, though the use of locking instead +is sufficient. + +Mandatory barriers should not be used to control SMP effects, since mandatory +barriers unnecessarily impose overhead on UP systems. They may, however, be +used to control MMIO effects on accesses through relaxed memory I/O windows. +These are required even on non-SMP systems as they affect the order in which +memory operations appear to a device by prohibiting both the compiler and the +CPU from reordering them. + + +There are some more advanced barrier functions: + + (*) set_mb(var, value) + (*) set_wmb(var, value) + + These assign the value to the variable and then insert at least a write + barrier after it, depending on the function. They aren't guaranteed to + insert anything more than a compiler barrier in a UP compilation. + + + (*) smp_mb__before_atomic_dec(); + (*) smp_mb__after_atomic_dec(); + (*) smp_mb__before_atomic_inc(); + (*) smp_mb__after_atomic_inc(); + + These are for use with atomic add, subtract, increment and decrement + functions, especially when used for reference counting. These functions + do not imply memory barriers. + + As an example, consider a piece of code that marks an object as being dead + and then decrements the object's reference count: + + obj->dead = 1; + smp_mb__before_atomic_dec(); + atomic_dec(&obj->ref_count); + + This makes sure that the death mark on the object is perceived to be set + *before* the reference counter is decremented. + + See Documentation/atomic_ops.txt for more information. See the "Atomic + operations" subsection for information on where to use these. + + + (*) smp_mb__before_clear_bit(void); + (*) smp_mb__after_clear_bit(void); + + These are for use similar to the atomic inc/dec barriers. These are + typically used for bitwise unlocking operations, so care must be taken as + there are no implicit memory barriers here either. + + Consider implementing an unlock operation of some nature by clearing a + locking bit. The clear_bit() would then need to be barriered like this: + + smp_mb__before_clear_bit(); + clear_bit( ... ); + + This prevents memory operations before the clear leaking to after it. See + the subsection on "Locking Functions" with reference to UNLOCK operation + implications. + + See Documentation/atomic_ops.txt for more information. See the "Atomic + operations" subsection for information on where to use these. + + +MMIO WRITE BARRIER +------------------ + +The Linux kernel also has a special barrier for use with memory-mapped I/O +writes: + + mmiowb(); + +This is a variation on the mandatory write barrier that causes writes to weakly +ordered I/O regions to be partially ordered. Its effects may go beyond the +CPU->Hardware interface and actually affect the hardware at some level. + +See the subsection "Locks vs I/O accesses" for more information. + + +=============================== +IMPLICIT KERNEL MEMORY BARRIERS +=============================== + +Some of the other functions in the linux kernel imply memory barriers, amongst +which are locking, scheduling and memory allocation functions. + +This specification is a _minimum_ guarantee; any particular architecture may +provide more substantial guarantees, but these may not be relied upon outside +of arch specific code. + + +LOCKING FUNCTIONS +----------------- + +The Linux kernel has a number of locking constructs: + + (*) spin locks + (*) R/W spin locks + (*) mutexes + (*) semaphores + (*) R/W semaphores + (*) RCU + +In all cases there are variants on "LOCK" operations and "UNLOCK" operations +for each construct. These operations all imply certain barriers: + + (1) LOCK operation implication: + + Memory operations issued after the LOCK will be completed after the LOCK + operation has completed. + + Memory operations issued before the LOCK may be completed after the LOCK + operation has completed. + + (2) UNLOCK operation implication: + + Memory operations issued before the UNLOCK will be completed before the + UNLOCK operation has completed. + + Memory operations issued after the UNLOCK may be completed before the + UNLOCK operation has completed. + + (3) LOCK vs LOCK implication: + + All LOCK operations issued before another LOCK operation will be completed + before that LOCK operation. + + (4) LOCK vs UNLOCK implication: + + All LOCK operations issued before an UNLOCK operation will be completed + before the UNLOCK operation. + + All UNLOCK operations issued before a LOCK operation will be completed + before the LOCK operation. + + (5) Failed conditional LOCK implication: + + Certain variants of the LOCK operation may fail, either due to being + unable to get the lock immediately, or due to receiving an unblocked + signal whilst asleep waiting for the lock to become available. Failed + locks do not imply any sort of barrier. + +Therefore, from (1), (2) and (4) an UNLOCK followed by an unconditional LOCK is +equivalent to a full barrier, but a LOCK followed by an UNLOCK is not. + +[!] Note: one of the consequence of LOCKs and UNLOCKs being only one-way + barriers is that the effects instructions outside of a critical section may + seep into the inside of the critical section. + +Locks and semaphores may not provide any guarantee of ordering on UP compiled +systems, and so cannot be counted on in such a situation to actually achieve +anything at all - especially with respect to I/O accesses - unless combined +with interrupt disabling operations. + +See also the section on "Inter-CPU locking barrier effects". + + +As an example, consider the following: + + *A = a; + *B = b; + LOCK + *C = c; + *D = d; + UNLOCK + *E = e; + *F = f; + +The following sequence of events is acceptable: + + LOCK, {*F,*A}, *E, {*C,*D}, *B, UNLOCK + + [+] Note that {*F,*A} indicates a combined access. + +But none of the following are: + + {*F,*A}, *B, LOCK, *C, *D, UNLOCK, *E + *A, *B, *C, LOCK, *D, UNLOCK, *E, *F + *A, *B, LOCK, *C, UNLOCK, *D, *E, *F + *B, LOCK, *C, *D, UNLOCK, {*F,*A}, *E + + + +INTERRUPT DISABLING FUNCTIONS +----------------------------- + +Functions that disable interrupts (LOCK equivalent) and enable interrupts +(UNLOCK equivalent) will act as compiler barriers only. So if memory or I/O +barriers are required in such a situation, they must be provided from some +other means. + + +MISCELLANEOUS FUNCTIONS +----------------------- + +Other functions that imply barriers: + + (*) schedule() and similar imply full memory barriers. + + (*) Memory allocation and release functions imply full memory barriers. + + +================================= +INTER-CPU LOCKING BARRIER EFFECTS +================================= + +On SMP systems locking primitives give a more substantial form of barrier: one +that does affect memory access ordering on other CPUs, within the context of +conflict on any particular lock. + + +LOCKS VS MEMORY ACCESSES +------------------------ + +Consider the following: the system has a pair of spinlocks (N) and (Q), and +three CPUs; then should the following sequence of events occur: + + CPU 1 CPU 2 + =============================== =============================== + *A = a; *E = e; + LOCK M LOCK Q + *B = b; *F = f; + *C = c; *G = g; + UNLOCK M UNLOCK Q + *D = d; *H = h; + +Then there is no guarantee as to what order CPU #3 will see the accesses to *A +through *H occur in, other than the constraints imposed by the separate locks +on the separate CPUs. It might, for example, see: + + *E, LOCK M, LOCK Q, *G, *C, *F, *A, *B, UNLOCK Q, *D, *H, UNLOCK M + +But it won't see any of: + + *B, *C or *D preceding LOCK M + *A, *B or *C following UNLOCK M + *F, *G or *H preceding LOCK Q + *E, *F or *G following UNLOCK Q + + +However, if the following occurs: + + CPU 1 CPU 2 + =============================== =============================== + *A = a; + LOCK M [1] + *B = b; + *C = c; + UNLOCK M [1] + *D = d; *E = e; + LOCK M [2] + *F = f; + *G = g; + UNLOCK M [2] + *H = h; + +CPU #3 might see: + + *E, LOCK M [1], *C, *B, *A, UNLOCK M [1], + LOCK M [2], *H, *F, *G, UNLOCK M [2], *D + +But assuming CPU #1 gets the lock first, it won't see any of: + + *B, *C, *D, *F, *G or *H preceding LOCK M [1] + *A, *B or *C following UNLOCK M [1] + *F, *G or *H preceding LOCK M [2] + *A, *B, *C, *E, *F or *G following UNLOCK M [2] + + +LOCKS VS I/O ACCESSES +--------------------- + +Under certain circumstances (especially involving NUMA), I/O accesses within +two spinlocked sections on two different CPUs may be seen as interleaved by the +PCI bridge, because the PCI bridge does not necessarily participate in the +cache-coherence protocol, and is therefore incapable of issuing the required +read memory barriers. + +For example: + + CPU 1 CPU 2 + =============================== =============================== + spin_lock(Q) + writel(0, ADDR) + writel(1, DATA); + spin_unlock(Q); + spin_lock(Q); + writel(4, ADDR); + writel(5, DATA); + spin_unlock(Q); + +may be seen by the PCI bridge as follows: + + STORE *ADDR = 0, STORE *ADDR = 4, STORE *DATA = 1, STORE *DATA = 5 + +which would probably cause the hardware to malfunction. + + +What is necessary here is to intervene with an mmiowb() before dropping the +spinlock, for example: + + CPU 1 CPU 2 + =============================== =============================== + spin_lock(Q) + writel(0, ADDR) + writel(1, DATA); + mmiowb(); + spin_unlock(Q); + spin_lock(Q); + writel(4, ADDR); + writel(5, DATA); + mmiowb(); + spin_unlock(Q); + +this will ensure that the two stores issued on CPU #1 appear at the PCI bridge +before either of the stores issued on CPU #2. + + +Furthermore, following a store by a load to the same device obviates the need +for an mmiowb(), because the load forces the store to complete before the load +is performed: + + CPU 1 CPU 2 + =============================== =============================== + spin_lock(Q) + writel(0, ADDR) + a = readl(DATA); + spin_unlock(Q); + spin_lock(Q); + writel(4, ADDR); + b = readl(DATA); + spin_unlock(Q); + + +See Documentation/DocBook/deviceiobook.tmpl for more information. + + +================================= +WHERE ARE MEMORY BARRIERS NEEDED? +================================= + +Under normal operation, memory operation reordering is generally not going to +be a problem as a single-threaded linear piece of code will still appear to +work correctly, even if it's in an SMP kernel. There are, however, three +circumstances in which reordering definitely _could_ be a problem: + + (*) Interprocessor interaction. + + (*) Atomic operations. + + (*) Accessing devices (I/O). + + (*) Interrupts. + + +INTERPROCESSOR INTERACTION +-------------------------- + +When there's a system with more than one processor, more than one CPU in the +system may be working on the same data set at the same time. This can cause +synchronisation problems, and the usual way of dealing with them is to use +locks. Locks, however, are quite expensive, and so it may be preferable to +operate without the use of a lock if at all possible. In such a case +operations that affect both CPUs may have to be carefully ordered to prevent +a malfunction. + +Consider, for example, the R/W semaphore slow path. Here a waiting process is +queued on the semaphore, by virtue of it having a piece of its stack linked to +the semaphore's list of waiting processes: + + struct rw_semaphore { + ... + spinlock_t lock; + struct list_head waiters; + }; + + struct rwsem_waiter { + struct list_head list; + struct task_struct *task; + }; + +To wake up a particular waiter, the up_read() or up_write() functions have to: + + (1) read the next pointer from this waiter's record to know as to where the + next waiter record is; + + (4) read the pointer to the waiter's task structure; + + (3) clear the task pointer to tell the waiter it has been given the semaphore; + + (4) call wake_up_process() on the task; and + + (5) release the reference held on the waiter's task struct. + +In otherwords, it has to perform this sequence of events: + + LOAD waiter->list.next; + LOAD waiter->task; + STORE waiter->task; + CALL wakeup + RELEASE task + +and if any of these steps occur out of order, then the whole thing may +malfunction. + +Once it has queued itself and dropped the semaphore lock, the waiter does not +get the lock again; it instead just waits for its task pointer to be cleared +before proceeding. Since the record is on the waiter's stack, this means that +if the task pointer is cleared _before_ the next pointer in the list is read, +another CPU might start processing the waiter and might clobber the waiter's +stack before the up*() function has a chance to read the next pointer. + +Consider then what might happen to the above sequence of events: + + CPU 1 CPU 2 + =============================== =============================== + down_xxx() + Queue waiter + Sleep + up_yyy() + LOAD waiter->task; + STORE waiter->task; + Woken up by other event + + Resume processing + down_xxx() returns + call foo() + foo() clobbers *waiter + + LOAD waiter->list.next; + --- OOPS --- + +This could be dealt with using the semaphore lock, but then the down_xxx() +function has to needlessly get the spinlock again after being woken up. + +The way to deal with this is to insert a general SMP memory barrier: + + LOAD waiter->list.next; + LOAD waiter->task; + smp_mb(); + STORE waiter->task; + CALL wakeup + RELEASE task + +In this case, the barrier makes a guarantee that all memory accesses before the +barrier will appear to happen before all the memory accesses after the barrier +with respect to the other CPUs on the system. It does _not_ guarantee that all +the memory accesses before the barrier will be complete by the time the barrier +instruction itself is complete. + +On a UP system - where this wouldn't be a problem - the smp_mb() is just a +compiler barrier, thus making sure the compiler emits the instructions in the +right order without actually intervening in the CPU. Since there there's only +one CPU, that CPU's dependency ordering logic will take care of everything +else. + + +ATOMIC OPERATIONS +----------------- + +Though they are technically interprocessor interaction considerations, atomic +operations are noted specially as they do _not_ generally imply memory +barriers. The possible offenders include: + + xchg(); + cmpxchg(); + test_and_set_bit(); + test_and_clear_bit(); + test_and_change_bit(); + atomic_cmpxchg(); + atomic_inc_return(); + atomic_dec_return(); + atomic_add_return(); + atomic_sub_return(); + atomic_inc_and_test(); + atomic_dec_and_test(); + atomic_sub_and_test(); + atomic_add_negative(); + atomic_add_unless(); + +These may be used for such things as implementing LOCK operations or controlling +the lifetime of objects by decreasing their reference counts. In such cases +they need preceding memory barriers. + +The following may also be possible offenders as they may be used as UNLOCK +operations. + + set_bit(); + clear_bit(); + change_bit(); + atomic_set(); + + +The following are a little tricky: + + atomic_add(); + atomic_sub(); + atomic_inc(); + atomic_dec(); + +If they're used for statistics generation, then they probably don't need memory +barriers, unless there's a coupling between statistical data. + +If they're used for reference counting on an object to control its lifetime, +they probably don't need memory barriers because either the reference count +will be adjusted inside a locked section, or the caller will already hold +sufficient references to make the lock, and thus a memory barrier unnecessary. + +If they're used for constructing a lock of some description, then they probably +do need memory barriers as a lock primitive generally has to do things in a +specific order. + + +Basically, each usage case has to be carefully considered as to whether memory +barriers are needed or not. The simplest rule is probably: if the atomic +operation is protected by a lock, then it does not require a barrier unless +there's another operation within the critical section with respect to which an +ordering must be maintained. + +See Documentation/atomic_ops.txt for more information. + + +ACCESSING DEVICES +----------------- + +Many devices can be memory mapped, and so appear to the CPU as if they're just +a set of memory locations. To control such a device, the driver usually has to +make the right memory accesses in exactly the right order. + +However, having a clever CPU or a clever compiler creates a potential problem +in that the carefully sequenced accesses in the driver code won't reach the +device in the requisite order if the CPU or the compiler thinks it is more +efficient to reorder, combine or merge accesses - something that would cause +the device to malfunction. + +Inside of the Linux kernel, I/O should be done through the appropriate accessor +routines - such as inb() or writel() - which know how to make such accesses +appropriately sequential. Whilst this, for the most part, renders the explicit +use of memory barriers unnecessary, there are a couple of situations where they +might be needed: + + (1) On some systems, I/O stores are not strongly ordered across all CPUs, and + so for _all_ general drivers locks should be used and mmiowb() must be + issued prior to unlocking the critical section. + + (2) If the accessor functions are used to refer to an I/O memory window with + relaxed memory access properties, then _mandatory_ memory barriers are + required to enforce ordering. + +See Documentation/DocBook/deviceiobook.tmpl for more information. + + +INTERRUPTS +---------- + +A driver may be interrupted by its own interrupt service routine, and thus the +two parts of the driver may interfere with each other's attempts to control or +access the device. + +This may be alleviated - at least in part - by disabling local interrupts (a +form of locking), such that the critical operations are all contained within +the interrupt-disabled section in the driver. Whilst the driver's interrupt +routine is executing, the driver's core may not run on the same CPU, and its +interrupt is not permitted to happen again until the current interrupt has been +handled, thus the interrupt handler does not need to lock against that. + +However, consider a driver that was talking to an ethernet card that sports an +address register and a data register. If that driver's core talks to the card +under interrupt-disablement and then the driver's interrupt handler is invoked: + + LOCAL IRQ DISABLE + writew(ADDR, 3); + writew(DATA, y); + LOCAL IRQ ENABLE + + writew(ADDR, 4); + q = readw(DATA); + + +The store to the data register might happen after the second store to the +address register if ordering rules are sufficiently relaxed: + + STORE *ADDR = 3, STORE *ADDR = 4, STORE *DATA = y, q = LOAD *DATA + + +If ordering rules are relaxed, it must be assumed that accesses done inside an +interrupt disabled section may leak outside of it and may interleave with +accesses performed in an interrupt - and vice versa - unless implicit or +explicit barriers are used. + +Normally this won't be a problem because the I/O accesses done inside such +sections will include synchronous load operations on strictly ordered I/O +registers that form implicit I/O barriers. If this isn't sufficient then an +mmiowb() may need to be used explicitly. + + +A similar situation may occur between an interrupt routine and two routines +running on separate CPUs that communicate with each other. If such a case is +likely, then interrupt-disabling locks should be used to guarantee ordering. + + +========================== +KERNEL I/O BARRIER EFFECTS +========================== + +When accessing I/O memory, drivers should use the appropriate accessor +functions: + + (*) inX(), outX(): + + These are intended to talk to I/O space rather than memory space, but + that's primarily a CPU-specific concept. The i386 and x86_64 processors do + indeed have special I/O space access cycles and instructions, but many + CPUs don't have such a concept. + + The PCI bus, amongst others, defines an I/O space concept - which on such + CPUs as i386 and x86_64 cpus readily maps to the CPU's concept of I/O + space. However, it may also mapped as a virtual I/O space in the CPU's + memory map, particularly on those CPUs that don't support alternate + I/O spaces. + + Accesses to this space may be fully synchronous (as on i386), but + intermediary bridges (such as the PCI host bridge) may not fully honour + that. + + They are guaranteed to be fully ordered with respect to each other. + + They are not guaranteed to be fully ordered with respect to other types of + memory and I/O operation. + + (*) readX(), writeX(): + + Whether these are guaranteed to be fully ordered and uncombined with + respect to each other on the issuing CPU depends on the characteristics + defined for the memory window through which they're accessing. On later + i386 architecture machines, for example, this is controlled by way of the + MTRR registers. + + Ordinarily, these will be guaranteed to be fully ordered and uncombined,, + provided they're not accessing a prefetchable device. + + However, intermediary hardware (such as a PCI bridge) may indulge in + deferral if it so wishes; to flush a store, a load from the same location + is preferred[*], but a load from the same device or from configuration + space should suffice for PCI. + + [*] NOTE! attempting to load from the same location as was written to may + cause a malfunction - consider the 16550 Rx/Tx serial registers for + example. + + Used with prefetchable I/O memory, an mmiowb() barrier may be required to + force stores to be ordered. + + Please refer to the PCI specification for more information on interactions + between PCI transactions. + + (*) readX_relaxed() + + These are similar to readX(), but are not guaranteed to be ordered in any + way. Be aware that there is no I/O read barrier available. + + (*) ioreadX(), iowriteX() + + These will perform as appropriate for the type of access they're actually + doing, be it inX()/outX() or readX()/writeX(). + + +======================================== +ASSUMED MINIMUM EXECUTION ORDERING MODEL +======================================== + +It has to be assumed that the conceptual CPU is weakly-ordered but that it will +maintain the appearance of program causality with respect to itself. Some CPUs +(such as i386 or x86_64) are more constrained than others (such as powerpc or +frv), and so the most relaxed case (namely DEC Alpha) must be assumed outside +of arch-specific code. + +This means that it must be considered that the CPU will execute its instruction +stream in any order it feels like - or even in parallel - provided that if an +instruction in the stream depends on the an earlier instruction, then that +earlier instruction must be sufficiently complete[*] before the later +instruction may proceed; in other words: provided that the appearance of +causality is maintained. + + [*] Some instructions have more than one effect - such as changing the + condition codes, changing registers or changing memory - and different + instructions may depend on different effects. + +A CPU may also discard any instruction sequence that winds up having no +ultimate effect. For example, if two adjacent instructions both load an +immediate value into the same register, the first may be discarded. + + +Similarly, it has to be assumed that compiler might reorder the instruction +stream in any way it sees fit, again provided the appearance of causality is +maintained. + + +============================ +THE EFFECTS OF THE CPU CACHE +============================ + +The way cached memory operations are perceived across the system is affected to +a certain extent by the caches that lie between CPUs and memory, and by the +memory coherence system that maintains the consistency of state in the system. + +As far as the way a CPU interacts with another part of the system through the +caches goes, the memory system has to include the CPU's caches, and memory +barriers for the most part act at the interface between the CPU and its cache +(memory barriers logically act on the dotted line in the following diagram): + + <--- CPU ---> : <----------- Memory -----------> + : + +--------+ +--------+ : +--------+ +-----------+ + | | | | : | | | | +--------+ + | CPU | | Memory | : | CPU | | | | | + | Core |--->| Access |----->| Cache |<-->| | | | + | | | Queue | : | | | |--->| Memory | + | | | | : | | | | | | + +--------+ +--------+ : +--------+ | | | | + : | Cache | +--------+ + : | Coherency | + : | Mechanism | +--------+ + +--------+ +--------+ : +--------+ | | | | + | | | | : | | | | | | + | CPU | | Memory | : | CPU | | |--->| Device | + | Core |--->| Access |----->| Cache |<-->| | | | + | | | Queue | : | | | | | | + | | | | : | | | | +--------+ + +--------+ +--------+ : +--------+ +-----------+ + : + : + +Although any particular load or store may not actually appear outside of the +CPU that issued it since it may have been satisfied within the CPU's own cache, +it will still appear as if the full memory access had taken place as far as the +other CPUs are concerned since the cache coherency mechanisms will migrate the +cacheline over to the accessing CPU and propagate the effects upon conflict. + +The CPU core may execute instructions in any order it deems fit, provided the +expected program causality appears to be maintained. Some of the instructions +generate load and store operations which then go into the queue of memory +accesses to be performed. The core may place these in the queue in any order +it wishes, and continue execution until it is forced to wait for an instruction +to complete. + +What memory barriers are concerned with is controlling the order in which +accesses cross from the CPU side of things to the memory side of things, and +the order in which the effects are perceived to happen by the other observers +in the system. + +[!] Memory barriers are _not_ needed within a given CPU, as CPUs always see +their own loads and stores as if they had happened in program order. + +[!] MMIO or other device accesses may bypass the cache system. This depends on +the properties of the memory window through which devices are accessed and/or +the use of any special device communication instructions the CPU may have. + + +CACHE COHERENCY +--------------- + +Life isn't quite as simple as it may appear above, however: for while the +caches are expected to be coherent, there's no guarantee that that coherency +will be ordered. This means that whilst changes made on one CPU will +eventually become visible on all CPUs, there's no guarantee that they will +become apparent in the same order on those other CPUs. + + +Consider dealing with a system that has pair of CPUs (1 & 2), each of which has +a pair of parallel data caches (CPU 1 has A/B, and CPU 2 has C/D): + + : + : +--------+ + : +---------+ | | + +--------+ : +--->| Cache A |<------->| | + | | : | +---------+ | | + | CPU 1 |<---+ | | + | | : | +---------+ | | + +--------+ : +--->| Cache B |<------->| | + : +---------+ | | + : | Memory | + : +---------+ | System | + +--------+ : +--->| Cache C |<------->| | + | | : | +---------+ | | + | CPU 2 |<---+ | | + | | : | +---------+ | | + +--------+ : +--->| Cache D |<------->| | + : +---------+ | | + : +--------+ + : + +Imagine the system has the following properties: + + (*) an odd-numbered cache line may be in cache A, cache C or it may still be + resident in memory; + + (*) an even-numbered cache line may be in cache B, cache D or it may still be + resident in memory; + + (*) whilst the CPU core is interrogating one cache, the other cache may be + making use of the bus to access the rest of the system - perhaps to + displace a dirty cacheline or to do a speculative load; + + (*) each cache has a queue of operations that need to be applied to that cache + to maintain coherency with the rest of the system; + + (*) the coherency queue is not flushed by normal loads to lines already + present in the cache, even though the contents of the queue may + potentially effect those loads. + +Imagine, then, that two writes are made on the first CPU, with a write barrier +between them to guarantee that they will appear to reach that CPU's caches in +the requisite order: + + CPU 1 CPU 2 COMMENT + =============== =============== ======================================= + u == 0, v == 1 and p == &u, q == &u + v = 2; + smp_wmb(); Make sure change to v visible before + change to p + v is now in cache A exclusively + p = &v; + p is now in cache B exclusively + +The write memory barrier forces the other CPUs in the system to perceive that +the local CPU's caches have apparently been updated in the correct order. But +now imagine that the second CPU that wants to read those values: + + CPU 1 CPU 2 COMMENT + =============== =============== ======================================= + ... + q = p; + x = *q; + +The above pair of reads may then fail to happen in expected order, as the +cacheline holding p may get updated in one of the second CPU's caches whilst +the update to the cacheline holding v is delayed in the other of the second +CPU's caches by some other cache event: + + CPU 1 CPU 2 COMMENT + =============== =============== ======================================= + u == 0, v == 1 and p == &u, q == &u + v = 2; + smp_wmb(); + + + p = &b; q = p; + + + + x = *q; + Reads from v before v updated in cache + + + +Basically, whilst both cachelines will be updated on CPU 2 eventually, there's +no guarantee that, without intervention, the order of update will be the same +as that committed on CPU 1. + + +To intervene, we need to interpolate a data dependency barrier or a read +barrier between the loads. This will force the cache to commit its coherency +queue before processing any further requests: + + CPU 1 CPU 2 COMMENT + =============== =============== ======================================= + u == 0, v == 1 and p == &u, q == &u + v = 2; + smp_wmb(); + + + p = &b; q = p; + + + + smp_read_barrier_depends() + + + x = *q; + Reads from v after v updated in cache + + +This sort of problem can be encountered on DEC Alpha processors as they have a +split cache that improves performance by making better use of the data bus. +Whilst most CPUs do imply a data dependency barrier on the read when a memory +access depends on a read, not all do, so it may not be relied on. + +Other CPUs may also have split caches, but must coordinate between the various +cachelets for normal memory accesss. The semantics of the Alpha removes the +need for coordination in absence of memory barriers. + + +CACHE COHERENCY VS DMA +---------------------- + +Not all systems maintain cache coherency with respect to devices doing DMA. In +such cases, a device attempting DMA may obtain stale data from RAM because +dirty cache lines may be resident in the caches of various CPUs, and may not +have been written back to RAM yet. To deal with this, the appropriate part of +the kernel must flush the overlapping bits of cache on each CPU (and maybe +invalidate them as well). + +In addition, the data DMA'd to RAM by a device may be overwritten by dirty +cache lines being written back to RAM from a CPU's cache after the device has +installed its own data, or cache lines simply present in a CPUs cache may +simply obscure the fact that RAM has been updated, until at such time as the +cacheline is discarded from the CPU's cache and reloaded. To deal with this, +the appropriate part of the kernel must invalidate the overlapping bits of the +cache on each CPU. + +See Documentation/cachetlb.txt for more information on cache management. + + +CACHE COHERENCY VS MMIO +----------------------- + +Memory mapped I/O usually takes place through memory locations that are part of +a window in the CPU's memory space that have different properties assigned than +the usual RAM directed window. + +Amongst these properties is usually the fact that such accesses bypass the +caching entirely and go directly to the device buses. This means MMIO accesses +may, in effect, overtake accesses to cached memory that were emitted earlier. +A memory barrier isn't sufficient in such a case, but rather the cache must be +flushed between the cached memory write and the MMIO access if the two are in +any way dependent. + + +========================= +THE THINGS CPUS GET UP TO +========================= + +A programmer might take it for granted that the CPU will perform memory +operations in exactly the order specified, so that if a CPU is, for example, +given the following piece of code to execute: + + a = *A; + *B = b; + c = *C; + d = *D; + *E = e; + +They would then expect that the CPU will complete the memory operation for each +instruction before moving on to the next one, leading to a definite sequence of +operations as seen by external observers in the system: + + LOAD *A, STORE *B, LOAD *C, LOAD *D, STORE *E. + + +Reality is, of course, much messier. With many CPUs and compilers, the above +assumption doesn't hold because: + + (*) loads are more likely to need to be completed immediately to permit + execution progress, whereas stores can often be deferred without a + problem; + + (*) loads may be done speculatively, and the result discarded should it prove + to have been unnecessary; + + (*) loads may be done speculatively, leading to the result having being + fetched at the wrong time in the expected sequence of events; + + (*) the order of the memory accesses may be rearranged to promote better use + of the CPU buses and caches; + + (*) loads and stores may be combined to improve performance when talking to + memory or I/O hardware that can do batched accesses of adjacent locations, + thus cutting down on transaction setup costs (memory and PCI devices may + both be able to do this); and + + (*) the CPU's data cache may affect the ordering, and whilst cache-coherency + mechanisms may alleviate this - once the store has actually hit the cache + - there's no guarantee that the coherency management will be propagated in + order to other CPUs. + +So what another CPU, say, might actually observe from the above piece of code +is: + + LOAD *A, ..., LOAD {*C,*D}, STORE *E, STORE *B + + (Where "LOAD {*C,*D}" is a combined load) + + +However, it is guaranteed that a CPU will be self-consistent: it will see its +_own_ accesses appear to be correctly ordered, without the need for a memory +barrier. For instance with the following code: + + U = *A; + *A = V; + *A = W; + X = *A; + *A = Y; + Z = *A; + +and assuming no intervention by an external influence, it can be assumed that +the final result will appear to be: + + U == the original value of *A + X == W + Z == Y + *A == Y + +The code above may cause the CPU to generate the full sequence of memory +accesses: + + U=LOAD *A, STORE *A=V, STORE *A=W, X=LOAD *A, STORE *A=Y, Z=LOAD *A + +in that order, but, without intervention, the sequence may have almost any +combination of elements combined or discarded, provided the program's view of +the world remains consistent. + +The compiler may also combine, discard or defer elements of the sequence before +the CPU even sees them. + +For instance: + + *A = V; + *A = W; + +may be reduced to: + + *A = W; + +since, without a write barrier, it can be assumed that the effect of the +storage of V to *A is lost. Similarly: + + *A = Y; + Z = *A; + +may, without a memory barrier, be reduced to: + + *A = Y; + Z = Y; + +and the LOAD operation never appear outside of the CPU. + + +AND THEN THERE'S THE ALPHA +-------------------------- + +The DEC Alpha CPU is one of the most relaxed CPUs there is. Not only that, +some versions of the Alpha CPU have a split data cache, permitting them to have +two semantically related cache lines updating at separate times. This is where +the data dependency barrier really becomes necessary as this synchronises both +caches with the memory coherence system, thus making it seem like pointer +changes vs new data occur in the right order. + +The Alpha defines the Linux's kernel's memory barrier model. + +See the subsection on "Cache Coherency" above. + + +========== +REFERENCES +========== + +Alpha AXP Architecture Reference Manual, Second Edition (Sites & Witek, +Digital Press) + Chapter 5.2: Physical Address Space Characteristics + Chapter 5.4: Caches and Write Buffers + Chapter 5.5: Data Sharing + Chapter 5.6: Read/Write Ordering + +AMD64 Architecture Programmer's Manual Volume 2: System Programming + Chapter 7.1: Memory-Access Ordering + Chapter 7.4: Buffering and Combining Memory Writes + +IA-32 Intel Architecture Software Developer's Manual, Volume 3: +System Programming Guide + Chapter 7.1: Locked Atomic Operations + Chapter 7.2: Memory Ordering + Chapter 7.4: Serializing Instructions + +The SPARC Architecture Manual, Version 9 + Chapter 8: Memory Models + Appendix D: Formal Specification of the Memory Models + Appendix J: Programming with the Memory Models + +UltraSPARC Programmer Reference Manual + Chapter 5: Memory Accesses and Cacheability + Chapter 15: Sparc-V9 Memory Models + +UltraSPARC III Cu User's Manual + Chapter 9: Memory Models + +UltraSPARC IIIi Processor User's Manual + Chapter 8: Memory Models + +UltraSPARC Architecture 2005 + Chapter 9: Memory + Appendix D: Formal Specifications of the Memory Models + +UltraSPARC T1 Supplement to the UltraSPARC Architecture 2005 + Chapter 8: Memory Models + Appendix F: Caches and Cache Coherency + +Solaris Internals, Core Kernel Architecture, p63-68: + Chapter 3.3: Hardware Considerations for Locks and + Synchronization + +Unix Systems for Modern Architectures, Symmetric Multiprocessing and Caching +for Kernel Programmers: + Chapter 13: Other Memory Models + +Intel Itanium Architecture Software Developer's Manual: Volume 1: + Section 2.6: Speculation + Section 4.4: Memory Access -- cgit v1.2.2 From 58ef2c4ce3c98fe46ae159bd560b63421798ea90 Mon Sep 17 00:00:00 2001 From: Adrian Bunk Date: Sat, 1 Apr 2006 01:04:59 +0200 Subject: typos: s/ducument/document/ s/ducument/document/ Signed-off-by: Adrian Bunk --- Documentation/DocBook/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index 7d87dd73cbe4..5a2882d275ba 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -2,7 +2,7 @@ # This makefile is used to generate the kernel documentation, # primarily based on in-line comments in various source files. # See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how -# to ducument the SRC - and how to read it. +# to document the SRC - and how to read it. # To add a new book the only step required is to add the book to the # list of DOCBOOKS. -- cgit v1.2.2 From 2e150f6e1a0401ff6af7b3f6518139fb092f3dd3 Mon Sep 17 00:00:00 2001 From: Uwe Zeisberger Date: Sat, 1 Apr 2006 01:29:43 +0200 Subject: fix typo "Suposse" -> "Suppose" Signed-off-by: Uwe Zeisberger Signed-off-by: Adrian Bunk --- Documentation/networking/packet_mmap.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/networking/packet_mmap.txt b/Documentation/networking/packet_mmap.txt index 4fc8e9874320..aaf99d5f0dad 100644 --- a/Documentation/networking/packet_mmap.txt +++ b/Documentation/networking/packet_mmap.txt @@ -254,7 +254,7 @@ and, the number of frames be * / -Suposse the following parameters, which apply for 2.6 kernel and an +Suppose the following parameters, which apply for 2.6 kernel and an i386 architecture: = 131072 bytes -- cgit v1.2.2 From abe37e5a13c4055bdf8ea1d2e781d757285e1908 Mon Sep 17 00:00:00 2001 From: Horms Date: Sat, 1 Apr 2006 01:36:09 +0200 Subject: Documentation: Reorder documentation of nomca and nomce My patch to add brief documentation of the nomca boot parameter added it out of alphabetical order. Signed-Off-By: Horms Signed-off-by: Adrian Bunk --- Documentation/kernel-parameters.txt | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f8cb55c30b0f..f5863b04a072 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1046,10 +1046,10 @@ running once the system is up. noltlbs [PPC] Do not use large page/tlb entries for kernel lowmem mapping on PPC40x. - nomce [IA-32] Machine Check Exception - nomca [IA-64] Disable machine check abort handling + nomce [IA-32] Machine Check Exception + noresidual [PPC] Don't use residual data on PReP machines. noresume [SWSUSP] Disables resume and restores original swap -- cgit v1.2.2 From 08039264d55b1e4c481309d841b245b0bb5e9c68 Mon Sep 17 00:00:00 2001 From: Horms Date: Sat, 1 Apr 2006 01:38:15 +0200 Subject: Documentation: Make fujitsu/frv/kernel-ABI.txt 80 columns wide Documentation: Make kernel-ABI.txt 80 columns wide Note that this only has line-wrapping and white-space changes. No text was changed at all. Signed-Off-By: Horms Signed-off-by: Adrian Bunk --- Documentation/fujitsu/frv/kernel-ABI.txt | 192 ++++++++++++++++++------------- 1 file changed, 110 insertions(+), 82 deletions(-) (limited to 'Documentation') diff --git a/Documentation/fujitsu/frv/kernel-ABI.txt b/Documentation/fujitsu/frv/kernel-ABI.txt index 0ed9b0a779bc..8b0a5fc8bfd9 100644 --- a/Documentation/fujitsu/frv/kernel-ABI.txt +++ b/Documentation/fujitsu/frv/kernel-ABI.txt @@ -1,17 +1,19 @@ - ================================= - INTERNAL KERNEL ABI FOR FR-V ARCH - ================================= - -The internal FRV kernel ABI is not quite the same as the userspace ABI. A number of the registers -are used for special purposed, and the ABI is not consistent between modules vs core, and MMU vs -no-MMU. - -This partly stems from the fact that FRV CPUs do not have a separate supervisor stack pointer, and -most of them do not have any scratch registers, thus requiring at least one general purpose -register to be clobbered in such an event. Also, within the kernel core, it is possible to simply -jump or call directly between functions using a relative offset. This cannot be extended to modules -for the displacement is likely to be too far. Thus in modules the address of a function to call -must be calculated in a register and then used, requiring two extra instructions. + ================================= + INTERNAL KERNEL ABI FOR FR-V ARCH + ================================= + +The internal FRV kernel ABI is not quite the same as the userspace ABI. A +number of the registers are used for special purposed, and the ABI is not +consistent between modules vs core, and MMU vs no-MMU. + +This partly stems from the fact that FRV CPUs do not have a separate +supervisor stack pointer, and most of them do not have any scratch +registers, thus requiring at least one general purpose register to be +clobbered in such an event. Also, within the kernel core, it is possible to +simply jump or call directly between functions using a relative offset. +This cannot be extended to modules for the displacement is likely to be too +far. Thus in modules the address of a function to call must be calculated +in a register and then used, requiring two extra instructions. This document has the following sections: @@ -39,7 +41,8 @@ When a system call is made, the following registers are effective: CPU OPERATING MODES =================== -The FR-V CPU has three basic operating modes. In order of increasing capability: +The FR-V CPU has three basic operating modes. In order of increasing +capability: (1) User mode. @@ -47,42 +50,46 @@ The FR-V CPU has three basic operating modes. In order of increasing capability: (2) Kernel mode. - Normal kernel mode. There are many additional control registers available that may be - accessed in this mode, in addition to all the stuff available to user mode. This has two - submodes: + Normal kernel mode. There are many additional control registers + available that may be accessed in this mode, in addition to all the + stuff available to user mode. This has two submodes: (a) Exceptions enabled (PSR.T == 1). - Exceptions will invoke the appropriate normal kernel mode handler. On entry to the - handler, the PSR.T bit will be cleared. + Exceptions will invoke the appropriate normal kernel mode + handler. On entry to the handler, the PSR.T bit will be cleared. (b) Exceptions disabled (PSR.T == 0). - No exceptions or interrupts may happen. Any mandatory exceptions will cause the CPU to - halt unless the CPU is told to jump into debug mode instead. + No exceptions or interrupts may happen. Any mandatory exceptions + will cause the CPU to halt unless the CPU is told to jump into + debug mode instead. (3) Debug mode. - No exceptions may happen in this mode. Memory protection and management exceptions will be - flagged for later consideration, but the exception handler won't be invoked. Debugging traps - such as hardware breakpoints and watchpoints will be ignored. This mode is entered only by - debugging events obtained from the other two modes. + No exceptions may happen in this mode. Memory protection and + management exceptions will be flagged for later consideration, but + the exception handler won't be invoked. Debugging traps such as + hardware breakpoints and watchpoints will be ignored. This mode is + entered only by debugging events obtained from the other two modes. - All kernel mode registers may be accessed, plus a few extra debugging specific registers. + All kernel mode registers may be accessed, plus a few extra debugging + specific registers. ================================= INTERNAL KERNEL-MODE REGISTER ABI ================================= -There are a number of permanent register assignments that are set up by entry.S in the exception -prologue. Note that there is a complete set of exception prologues for each of user->kernel -transition and kernel->kernel transition. There are also user->debug and kernel->debug mode -transition prologues. +There are a number of permanent register assignments that are set up by +entry.S in the exception prologue. Note that there is a complete set of +exception prologues for each of user->kernel transition and kernel->kernel +transition. There are also user->debug and kernel->debug mode transition +prologues. REGISTER FLAVOUR USE - =============== ======= ==================================================== + =============== ======= ============================================== GR1 Supervisor stack pointer GR15 Current thread info pointer GR16 GP-Rel base register for small data @@ -92,10 +99,12 @@ transition prologues. GR31 NOMMU Destroyed by debug mode entry GR31 MMU Destroyed by TLB miss kernel mode entry CCR.ICC2 Virtual interrupt disablement tracking - CCCR.CC3 Cleared by exception prologue (atomic op emulation) + CCCR.CC3 Cleared by exception prologue + (atomic op emulation) SCR0 MMU See mmu-layout.txt. SCR1 MMU See mmu-layout.txt. - SCR2 MMU Save for EAR0 (destroyed by icache insns in debug mode) + SCR2 MMU Save for EAR0 (destroyed by icache insns + in debug mode) SCR3 MMU Save for GR31 during debug exceptions DAMR/IAMR NOMMU Fixed memory protection layout. DAMR/IAMR MMU See mmu-layout.txt. @@ -104,18 +113,21 @@ transition prologues. Certain registers are also used or modified across function calls: REGISTER CALL RETURN - =============== =============================== =============================== + =============== =============================== ====================== GR0 Fixed Zero - GR2 Function call frame pointer GR3 Special Preserved GR3-GR7 - Clobbered - GR8 Function call arg #1 Return value (or clobbered) - GR9 Function call arg #2 Return value MSW (or clobbered) + GR8 Function call arg #1 Return value + (or clobbered) + GR9 Function call arg #2 Return value MSW + (or clobbered) GR10-GR13 Function call arg #3-#6 Clobbered GR14 - Clobbered GR15-GR16 Special Preserved GR17-GR27 - Preserved - GR28-GR31 Special Only accessed explicitly + GR28-GR31 Special Only accessed + explicitly LR Return address after CALL Clobbered CCR/CCCR - Mostly Clobbered @@ -124,46 +136,53 @@ Certain registers are also used or modified across function calls: INTERNAL DEBUG-MODE REGISTER ABI ================================ -This is the same as the kernel-mode register ABI for functions calls. The difference is that in -debug-mode there's a different stack and a different exception frame. Almost all the global -registers from kernel-mode (including the stack pointer) may be changed. +This is the same as the kernel-mode register ABI for functions calls. The +difference is that in debug-mode there's a different stack and a different +exception frame. Almost all the global registers from kernel-mode +(including the stack pointer) may be changed. REGISTER FLAVOUR USE - =============== ======= ==================================================== + =============== ======= ============================================== GR1 Debug stack pointer GR16 GP-Rel base register for small data - GR31 Current debug exception frame pointer (__debug_frame) + GR31 Current debug exception frame pointer + (__debug_frame) SCR3 MMU Saved value of GR31 -Note that debug mode is able to interfere with the kernel's emulated atomic ops, so it must be -exceedingly careful not to do any that would interact with the main kernel in this regard. Hence -the debug mode code (gdbstub) is almost completely self-contained. The only external code used is -the sprintf family of functions. +Note that debug mode is able to interfere with the kernel's emulated atomic +ops, so it must be exceedingly careful not to do any that would interact +with the main kernel in this regard. Hence the debug mode code (gdbstub) is +almost completely self-contained. The only external code used is the +sprintf family of functions. -Futhermore, break.S is so complicated because single-step mode does not switch off on entry to an -exception. That means unless manually disabled, single-stepping will blithely go on stepping into -things like interrupts. See gdbstub.txt for more information. +Futhermore, break.S is so complicated because single-step mode does not +switch off on entry to an exception. That means unless manually disabled, +single-stepping will blithely go on stepping into things like interrupts. +See gdbstub.txt for more information. ========================== VIRTUAL INTERRUPT HANDLING ========================== -Because accesses to the PSR is so slow, and to disable interrupts we have to access it twice (once -to read and once to write), we don't actually disable interrupts at all if we don't have to. What -we do instead is use the ICC2 condition code flags to note virtual disablement, such that if we -then do take an interrupt, we note the flag, really disable interrupts, set another flag and resume -execution at the point the interrupt happened. Setting condition flags as a side effect of an -arithmetic or logical instruction is really fast. This use of the ICC2 only occurs within the +Because accesses to the PSR is so slow, and to disable interrupts we have +to access it twice (once to read and once to write), we don't actually +disable interrupts at all if we don't have to. What we do instead is use +the ICC2 condition code flags to note virtual disablement, such that if we +then do take an interrupt, we note the flag, really disable interrupts, set +another flag and resume execution at the point the interrupt happened. +Setting condition flags as a side effect of an arithmetic or logical +instruction is really fast. This use of the ICC2 only occurs within the kernel - it does not affect userspace. The flags we use are: (*) CCR.ICC2.Z [Zero flag] - Set to virtually disable interrupts, clear when interrupts are virtually enabled. Can be - modified by logical instructions without affecting the Carry flag. + Set to virtually disable interrupts, clear when interrupts are + virtually enabled. Can be modified by logical instructions without + affecting the Carry flag. (*) CCR.ICC2.C [Carry flag] @@ -176,8 +195,9 @@ What happens is this: ICC2.Z is 0, ICC2.C is 1. - (2) An interrupt occurs. The exception prologue examines ICC2.Z and determines that nothing needs - doing. This is done simply with an unlikely BEQ instruction. + (2) An interrupt occurs. The exception prologue examines ICC2.Z and + determines that nothing needs doing. This is done simply with an + unlikely BEQ instruction. (3) The interrupts are disabled (local_irq_disable) @@ -187,48 +207,56 @@ What happens is this: ICC2.Z would be set to 0. - A TIHI #2 instruction (trap #2 if condition HI - Z==0 && C==0) would be used to trap if - interrupts were now virtually enabled, but physically disabled - which they're not, so the - trap isn't taken. The kernel would then be back to state (1). + A TIHI #2 instruction (trap #2 if condition HI - Z==0 && C==0) would + be used to trap if interrupts were now virtually enabled, but + physically disabled - which they're not, so the trap isn't taken. The + kernel would then be back to state (1). - (5) An interrupt occurs. The exception prologue examines ICC2.Z and determines that the interrupt - shouldn't actually have happened. It jumps aside, and there disabled interrupts by setting - PSR.PIL to 14 and then it clears ICC2.C. + (5) An interrupt occurs. The exception prologue examines ICC2.Z and + determines that the interrupt shouldn't actually have happened. It + jumps aside, and there disabled interrupts by setting PSR.PIL to 14 + and then it clears ICC2.C. (6) If interrupts were then saved and disabled again (local_irq_save): - ICC2.Z would be shifted into the save variable and masked off (giving a 1). + ICC2.Z would be shifted into the save variable and masked off + (giving a 1). - ICC2.Z would then be set to 1 (thus unchanged), and ICC2.C would be unaffected (ie: 0). + ICC2.Z would then be set to 1 (thus unchanged), and ICC2.C would be + unaffected (ie: 0). (7) If interrupts were then restored from state (6) (local_irq_restore): - ICC2.Z would be set to indicate the result of XOR'ing the saved value (ie: 1) with 1, which - gives a result of 0 - thus leaving ICC2.Z set. + ICC2.Z would be set to indicate the result of XOR'ing the saved + value (ie: 1) with 1, which gives a result of 0 - thus leaving + ICC2.Z set. ICC2.C would remain unaffected (ie: 0). - A TIHI #2 instruction would be used to again assay the current state, but this would do - nothing as Z==1. + A TIHI #2 instruction would be used to again assay the current state, + but this would do nothing as Z==1. (8) If interrupts were then enabled (local_irq_enable): - ICC2.Z would be cleared. ICC2.C would be left unaffected. Both flags would now be 0. + ICC2.Z would be cleared. ICC2.C would be left unaffected. Both + flags would now be 0. - A TIHI #2 instruction again issued to assay the current state would then trap as both Z==0 - [interrupts virtually enabled] and C==0 [interrupts really disabled] would then be true. + A TIHI #2 instruction again issued to assay the current state would + then trap as both Z==0 [interrupts virtually enabled] and C==0 + [interrupts really disabled] would then be true. - (9) The trap #2 handler would simply enable hardware interrupts (set PSR.PIL to 0), set ICC2.C to - 1 and return. + (9) The trap #2 handler would simply enable hardware interrupts + (set PSR.PIL to 0), set ICC2.C to 1 and return. (10) Immediately upon returning, the pending interrupt would be taken. -(11) The interrupt handler would take the path of actually processing the interrupt (ICC2.Z is - clear, BEQ fails as per step (2)). +(11) The interrupt handler would take the path of actually processing the + interrupt (ICC2.Z is clear, BEQ fails as per step (2)). -(12) The interrupt handler would then set ICC2.C to 1 since hardware interrupts are definitely - enabled - or else the kernel wouldn't be here. +(12) The interrupt handler would then set ICC2.C to 1 since hardware + interrupts are definitely enabled - or else the kernel wouldn't be here. (13) On return from the interrupt handler, things would be back to state (1). -This trap (#2) is only available in kernel mode. In user mode it will result in SIGILL. +This trap (#2) is only available in kernel mode. In user mode it will +result in SIGILL. -- cgit v1.2.2 From 0ee9d71f02b19f87368ee99b73019bf9522c7bf8 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Sat, 1 Apr 2006 01:42:29 +0200 Subject: Doc/kernel-parameters.txt: delete false version information and history Doc/kernel-parameters.txt: delete false version information and history Signed-off-by: Stefan Richter Signed-off-by: Adrian Bunk --- Documentation/kernel-parameters.txt | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f5863b04a072..5746dee1eff7 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1,4 +1,4 @@ -February 2003 Kernel Parameters v2.5.59 + Kernel Parameters ~~~~~~~~~~~~~~~~~ The following is a consolidated list of the kernel parameters as implemented @@ -1682,20 +1682,6 @@ running once the system is up. ______________________________________________________________________ -Changelog: - -2000-06-?? Mr. Unknown - The last known update (for 2.4.0) - the changelog was not kept before. - -2002-11-24 Petr Baudis - Randy Dunlap - Update for 2.5.49, description for most of the options introduced, - references to other documentation (C files, READMEs, ..), added S390, - PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and - reformatting. - -2005-10-19 Randy Dunlap - Lots of typos, whitespace, some reformatting. TODO: -- cgit v1.2.2 From a901ebb907e6aca38dc43417d6ce30f23651ea64 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Sat, 1 Apr 2006 01:43:18 +0200 Subject: Doc/kernel-parameters.txt: mention modinfo and sysfs Doc/kernel-parameters.txt: mention modinfo and sysfs Signed-off-by: Stefan Richter Signed-off-by: Adrian Bunk --- Documentation/kernel-parameters.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 5746dee1eff7..d057e9e74d38 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -17,6 +17,13 @@ are specified on the kernel command line with the module name plus usbcore.blinkenlights=1 +This document may not be entirely up to date and comprehensive. The command +"modinfo -p ${modulename}" shows a current list of all parameters of a loadable +module. Loadable modules, after being loaded into the running kernel, also +reveal their parameters in /sys/module/${modulename}/parameters/. Some of these +parameters may be changed at runtime by the command +"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". + The text in square brackets at the beginning of the description states the restrictions on the kernel for the said kernel parameter to be valid. The restrictions referred to are that the relevant option is valid if: -- cgit v1.2.2 From 6585fa8aa58c7cd9f90f1c795a9dfc8db5f13906 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Sat, 1 Apr 2006 01:44:30 +0200 Subject: Doc/kernel-parameters.txt: slightly reword sentence about restrictions The previous patch somewhat diverted the train of thought. Here I am trying to bring the valued reader back on track. Signed-off-by: Stefan Richter Signed-off-by: Adrian Bunk --- Documentation/kernel-parameters.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index d057e9e74d38..b3a6187e5305 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -24,9 +24,10 @@ reveal their parameters in /sys/module/${modulename}/parameters/. Some of these parameters may be changed at runtime by the command "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". -The text in square brackets at the beginning of the description states the -restrictions on the kernel for the said kernel parameter to be valid. The -restrictions referred to are that the relevant option is valid if: +The parameters listed below are only valid if certain kernel build options were +enabled and if respective hardware is present. The text in square brackets at +the beginning of each description states the restrictions within which a +parameter is applicable: ACPI ACPI support is enabled. ALSA ALSA sound support is enabled. -- cgit v1.2.2 From 3d79c33bbd1dd12d420fd84facfd0ba96261e595 Mon Sep 17 00:00:00 2001 From: Cal Peake Date: Sat, 1 Apr 2006 01:46:12 +0200 Subject: BFP->BPF in Documentation/networking/tuntap.txt BFP should be BPF (BSD Packet Filter) Signed-off-by: Cal Peake Signed-off-by: Adrian Bunk --- Documentation/networking/tuntap.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/networking/tuntap.txt b/Documentation/networking/tuntap.txt index ec3d109d787a..76750fb9151a 100644 --- a/Documentation/networking/tuntap.txt +++ b/Documentation/networking/tuntap.txt @@ -138,7 +138,7 @@ This means that you have to read/write IP packets when you are using tun and ethernet frames when using tap. 5. What is the difference between BPF and TUN/TAP driver? -BFP is an advanced packet filter. It can be attached to existing +BPF is an advanced packet filter. It can be attached to existing network interface. It does not provide a virtual network interface. A TUN/TAP driver does provide a virtual network interface and it is possible to attach BPF to this interface. -- cgit v1.2.2 From 409ca8c8ae3173026e7dfbdcdab669766e43fb60 Mon Sep 17 00:00:00 2001 From: Michael Hayes Date: Sat, 1 Apr 2006 01:49:22 +0200 Subject: Fix minor documentation typo This patch fixes a minor typo in Documentation/acpi-hotkey.txt. Signed-off-by: Adrian Bunk --- Documentation/acpi-hotkey.txt | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/acpi-hotkey.txt b/Documentation/acpi-hotkey.txt index 744f1aec6553..38040fa37649 100644 --- a/Documentation/acpi-hotkey.txt +++ b/Documentation/acpi-hotkey.txt @@ -30,7 +30,7 @@ specific hotkey(event)) echo "event_num:event_type:event_argument" > /proc/acpi/hotkey/action. The result of the execution of this aml method is -attached to /proc/acpi/hotkey/poll_method, which is dnyamically +attached to /proc/acpi/hotkey/poll_method, which is dynamically created. Please use command "cat /proc/acpi/hotkey/polling_method" to retrieve it. -- cgit v1.2.2 From b157d55eef38f014015b8058a9f733d1c1c49cb4 Mon Sep 17 00:00:00 2001 From: Raphael Assenat Date: Sun, 2 Apr 2006 00:10:05 -0500 Subject: Input: gamecon - add SNES mouse support SNES gamepads and mice share the same type of interface so they both can be connected to the parallel port using a simple interface. Adding mouse support to a gamepad driver may sound funny at first, but doing so in this case makes it possible to connect and SNES gamepads and mice at the same time, on the same port. Signed-off-by: Raphael Assenat Signed-off-by: Andrew Morton Signed-off-by: Dmitry Torokhov --- Documentation/input/joystick-parport.txt | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'Documentation') diff --git a/Documentation/input/joystick-parport.txt b/Documentation/input/joystick-parport.txt index 88a011c9f985..d537c48cc6d0 100644 --- a/Documentation/input/joystick-parport.txt +++ b/Documentation/input/joystick-parport.txt @@ -36,12 +36,12 @@ with them. All NES and SNES use the same synchronous serial protocol, clocked from the computer's side (and thus timing insensitive). To allow up to 5 NES -and/or SNES gamepads connected to the parallel port at once, the output -lines of the parallel port are shared, while one of 5 available input lines -is assigned to each gamepad. +and/or SNES gamepads and/or SNES mice connected to the parallel port at once, +the output lines of the parallel port are shared, while one of 5 available +input lines is assigned to each gamepad. This protocol is handled by the gamecon.c driver, so that's the one -you'll use for NES and SNES gamepads. +you'll use for NES, SNES gamepads and SNES mice. The main problem with PC parallel ports is that they don't have +5V power source on any of their pins. So, if you want a reliable source of power @@ -106,7 +106,7 @@ A, Turbo B, Select and Start, and is connected through 5 wires, then it is either a NES or NES clone and will work with this connection. SNES gamepads also use 5 wires, but have more buttons. They will work as well, of course. -Pinout for NES gamepads Pinout for SNES gamepads +Pinout for NES gamepads Pinout for SNES gamepads and mice +----> Power +-----------------------\ | 7 | o o o o | x x o | 1 @@ -454,6 +454,7 @@ uses the following kernel/module command line: 6 | N64 pad 7 | Sony PSX controller 8 | Sony PSX DDR controller + 9 | SNES mouse The exact type of the PSX controller type is autoprobed when used so hot swapping should work (but is not recomended). -- cgit v1.2.2 From 42e6b3b476f89b08232d1c1efd2327665b9050c8 Mon Sep 17 00:00:00 2001 From: Hartmut Hackmann Date: Mon, 27 Mar 2006 19:04:48 -0300 Subject: V4L/DVB (3644): Added PCI IDs of 2 LifeView Cards Added ID entries for the Genius VideoWonder DVB-T and the LifeView FlyTV Platinum Gold Signed-off-by: Hartmut Hackmann Signed-off-by: Mauro Carvalho Chehab --- Documentation/video4linux/CARDLIST.saa7134 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'Documentation') diff --git a/Documentation/video4linux/CARDLIST.saa7134 b/Documentation/video4linux/CARDLIST.saa7134 index 8c7195455963..b76cc6ebf406 100644 --- a/Documentation/video4linux/CARDLIST.saa7134 +++ b/Documentation/video4linux/CARDLIST.saa7134 @@ -52,7 +52,7 @@ 51 -> ProVideo PV952 [1540:9524] 52 -> AverMedia AverTV/305 [1461:2108] 53 -> ASUS TV-FM 7135 [1043:4845] - 54 -> LifeView FlyTV Platinum FM [5168:0214,1489:0214] + 54 -> LifeView FlyTV Platinum FM / Gold [5168:0214,1489:0214,5168:0304] 55 -> LifeView FlyDVB-T DUO [5168:0306] 56 -> Avermedia AVerTV 307 [1461:a70a] 57 -> Avermedia AVerTV GO 007 FM [1461:f31f] @@ -84,7 +84,7 @@ 83 -> Terratec Cinergy 250 PCI TV [153b:1160] 84 -> LifeView FlyDVB Trio [5168:0319] 85 -> AverTV DVB-T 777 [1461:2c05] - 86 -> LifeView FlyDVB-T [5168:0301] + 86 -> LifeView FlyDVB-T / Genius VideoWonder DVB-T [5168:0301,1489:0301] 87 -> ADS Instant TV Duo Cardbus PTV331 [0331:1421] 88 -> Tevion/KWorld DVB-T 220RF [17de:7201] 89 -> ELSA EX-VISION 700TV [1048:226c] -- cgit v1.2.2 From d95b8942eed310759bc866a2a4c0f110578aaa69 Mon Sep 17 00:00:00 2001 From: Hartmut Hackmann Date: Mon, 27 Mar 2006 19:39:30 -0300 Subject: V4L/DVB (3646): Added support for the new Lifeview hybrid cardbus modules There seem to be many variants of this cards with different feature sets. This entry supports analog TV, CVBS and s-video input, FM radio and DVB-T if they are supported by the hardware. Signed-off-by: Hartmut Hackmann Signed-off-by: Mauro Carvalho Chehab --- Documentation/video4linux/CARDLIST.saa7134 | 1 + 1 file changed, 1 insertion(+) (limited to 'Documentation') diff --git a/Documentation/video4linux/CARDLIST.saa7134 b/Documentation/video4linux/CARDLIST.saa7134 index b76cc6ebf406..bca50903233f 100644 --- a/Documentation/video4linux/CARDLIST.saa7134 +++ b/Documentation/video4linux/CARDLIST.saa7134 @@ -92,3 +92,4 @@ 91 -> AVerMedia A169 B [1461:7360] 92 -> AVerMedia A169 B1 [1461:6360] 93 -> Medion 7134 Bridge #2 [16be:0005] + 94 -> LifeView FlyDVB-T Hybrid Cardbus [5168:3306,5168:3502] -- cgit v1.2.2 From 1864cfb1537e108c2fe7a8e178b28bffde5a5439 Mon Sep 17 00:00:00 2001 From: Michael Krufky Date: Sun, 2 Apr 2006 03:14:11 -0300 Subject: V4L/DVB (3653h): Move usb v4l docs into Documentation/video4linux - Move documentation for usb v4l devices from Documentation/usb to Documentation/video4linux. - Removed trailing whitespace. - Update Kconfig help text links to reflect the new file locations. Signed-off-by: Michael Krufky Signed-off-by: Mauro Carvalho Chehab --- Documentation/usb/et61x251.txt | 314 -------------------- Documentation/usb/ibmcam.txt | 324 --------------------- Documentation/usb/ov511.txt | 289 ------------------ Documentation/usb/se401.txt | 54 ---- Documentation/usb/sn9c102.txt | 518 --------------------------------- Documentation/usb/stv680.txt | 55 ---- Documentation/usb/w9968cf.txt | 461 ----------------------------- Documentation/usb/zc0301.txt | 254 ---------------- Documentation/video4linux/et61x251.txt | 314 ++++++++++++++++++++ Documentation/video4linux/ibmcam.txt | 324 +++++++++++++++++++++ Documentation/video4linux/ov511.txt | 288 ++++++++++++++++++ Documentation/video4linux/se401.txt | 54 ++++ Documentation/video4linux/sn9c102.txt | 518 +++++++++++++++++++++++++++++++++ Documentation/video4linux/stv680.txt | 53 ++++ Documentation/video4linux/w9968cf.txt | 461 +++++++++++++++++++++++++++++ Documentation/video4linux/zc0301.txt | 254 ++++++++++++++++ 16 files changed, 2266 insertions(+), 2269 deletions(-) delete mode 100644 Documentation/usb/et61x251.txt delete mode 100644 Documentation/usb/ibmcam.txt delete mode 100644 Documentation/usb/ov511.txt delete mode 100644 Documentation/usb/se401.txt delete mode 100644 Documentation/usb/sn9c102.txt delete mode 100644 Documentation/usb/stv680.txt delete mode 100644 Documentation/usb/w9968cf.txt delete mode 100644 Documentation/usb/zc0301.txt create mode 100644 Documentation/video4linux/et61x251.txt create mode 100644 Documentation/video4linux/ibmcam.txt create mode 100644 Documentation/video4linux/ov511.txt create mode 100644 Documentation/video4linux/se401.txt create mode 100644 Documentation/video4linux/sn9c102.txt create mode 100644 Documentation/video4linux/stv680.txt create mode 100644 Documentation/video4linux/w9968cf.txt create mode 100644 Documentation/video4linux/zc0301.txt (limited to 'Documentation') diff --git a/Documentation/usb/et61x251.txt b/Documentation/usb/et61x251.txt deleted file mode 100644 index 29340282ab5f..000000000000 --- a/Documentation/usb/et61x251.txt +++ /dev/null @@ -1,314 +0,0 @@ - - ET61X[12]51 PC Camera Controllers - Driver for Linux - ================================= - - - Documentation - - - -Index -===== -1. Copyright -2. Disclaimer -3. License -4. Overview and features -5. Module dependencies -6. Module loading -7. Module parameters -8. Optional device control through "sysfs" -9. Supported devices -10. Notes for V4L2 application developers -11. Contact information - - -1. Copyright -============ -Copyright (C) 2006 by Luca Risolia - - -2. Disclaimer -============= -Etoms is a trademark of Etoms Electronics Corp. -This software is not developed or sponsored by Etoms Electronics. - - -3. License -========== -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program; if not, write to the Free Software -Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - -4. Overview and features -======================== -This driver supports the video interface of the devices mounting the ET61X151 -or ET61X251 PC Camera Controllers. - -It's worth to note that Etoms Electronics has never collaborated with the -author during the development of this project; despite several requests, -Etoms Electronics also refused to release enough detailed specifications of -the video compression engine. - -The driver relies on the Video4Linux2 and USB core modules. It has been -designed to run properly on SMP systems as well. - -The latest version of the ET61X[12]51 driver can be found at the following URL: -http://www.linux-projects.org/ - -Some of the features of the driver are: - -- full compliance with the Video4Linux2 API (see also "Notes for V4L2 - application developers" paragraph); -- available mmap or read/poll methods for video streaming through isochronous - data transfers; -- automatic detection of image sensor; -- support for any window resolutions and optional panning within the maximum - pixel area of image sensor; -- image downscaling with arbitrary scaling factors from 1 and 2 in both - directions (see "Notes for V4L2 application developers" paragraph); -- two different video formats for uncompressed or compressed data in low or - high compression quality (see also "Notes for V4L2 application developers" - paragraph); -- full support for the capabilities of every possible image sensors that can - be connected to the ET61X[12]51 bridges, including, for istance, red, green, - blue and global gain adjustments and exposure control (see "Supported - devices" paragraph for details); -- use of default color settings for sunlight conditions; -- dynamic I/O interface for both ET61X[12]51 and image sensor control (see - "Optional device control through 'sysfs'" paragraph); -- dynamic driver control thanks to various module parameters (see "Module - parameters" paragraph); -- up to 64 cameras can be handled at the same time; they can be connected and - disconnected from the host many times without turning off the computer, if - the system supports hotplugging; -- no known bugs. - - -5. Module dependencies -====================== -For it to work properly, the driver needs kernel support for Video4Linux and -USB. - -The following options of the kernel configuration file must be enabled and -corresponding modules must be compiled: - - # Multimedia devices - # - CONFIG_VIDEO_DEV=m - -To enable advanced debugging functionality on the device through /sysfs: - - # Multimedia devices - # - CONFIG_VIDEO_ADV_DEBUG=y - - # USB support - # - CONFIG_USB=m - -In addition, depending on the hardware being used, the modules below are -necessary: - - # USB Host Controller Drivers - # - CONFIG_USB_EHCI_HCD=m - CONFIG_USB_UHCI_HCD=m - CONFIG_USB_OHCI_HCD=m - -And finally: - - # USB Multimedia devices - # - CONFIG_USB_ET61X251=m - - -6. Module loading -================= -To use the driver, it is necessary to load the "et61x251" module into memory -after every other module required: "videodev", "usbcore" and, depending on -the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". - -Loading can be done as shown below: - - [root@localhost home]# modprobe et61x251 - -At this point the devices should be recognized. You can invoke "dmesg" to -analyze kernel messages and verify that the loading process has gone well: - - [user@localhost home]$ dmesg - - -7. Module parameters -==================== -Module parameters are listed below: -------------------------------------------------------------------------------- -Name: video_nr -Type: short array (min = 0, max = 64) -Syntax: <-1|n[,...]> -Description: Specify V4L2 minor mode number: - -1 = use next available - n = use minor number n - You can specify up to 64 cameras this way. - For example: - video_nr=-1,2,-1 would assign minor number 2 to the second - registered camera and use auto for the first one and for every - other camera. -Default: -1 -------------------------------------------------------------------------------- -Name: force_munmap -Type: bool array (min = 0, max = 64) -Syntax: <0|1[,...]> -Description: Force the application to unmap previously mapped buffer memory - before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not - all the applications support this feature. This parameter is - specific for each detected camera. - 0 = do not force memory unmapping - 1 = force memory unmapping (save memory) -Default: 0 -------------------------------------------------------------------------------- -Name: frame_timeout -Type: uint array (min = 0, max = 64) -Syntax: -Description: Timeout for a video frame in seconds. This parameter is - specific for each detected camera. This parameter can be - changed at runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- -Name: debug -Type: ushort -Syntax: -Description: Debugging information level, from 0 to 3: - 0 = none (use carefully) - 1 = critical errors - 2 = significant informations - 3 = more verbose messages - Level 3 is useful for testing only, when only one device - is used at the same time. It also shows some more informations - about the hardware being detected. This module parameter can be - changed at runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- - - -8. Optional device control through "sysfs" -========================================== -If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, -it is possible to read and write both the ET61X[12]51 and the image sensor -registers by using the "sysfs" filesystem interface. - -There are four files in the /sys/class/video4linux/videoX directory for each -registered camera: "reg", "val", "i2c_reg" and "i2c_val". The first two files -control the ET61X[12]51 bridge, while the other two control the sensor chip. -"reg" and "i2c_reg" hold the values of the current register index where the -following reading/writing operations are addressed at through "val" and -"i2c_val". Their use is not intended for end-users, unless you know what you -are doing. Remember that you must be logged in as root before writing to them. - -As an example, suppose we were to want to read the value contained in the -register number 1 of the sensor register table - which is usually the product -identifier - of the camera registered as "/dev/video0": - - [root@localhost #] cd /sys/class/video4linux/video0 - [root@localhost #] echo 1 > i2c_reg - [root@localhost #] cat i2c_val - -Note that if the sensor registers can not be read, "cat" will fail. -To avoid race conditions, all the I/O accesses to the files are serialized. - - -9. Supported devices -==================== -None of the names of the companies as well as their products will be mentioned -here. They have never collaborated with the author, so no advertising. - -From the point of view of a driver, what unambiguously identify a device are -its vendor and product USB identifiers. Below is a list of known identifiers of -devices mounting the ET61X[12]51 PC camera controllers: - -Vendor ID Product ID ---------- ---------- -0x102c 0x6151 -0x102c 0x6251 -0x102c 0x6253 -0x102c 0x6254 -0x102c 0x6255 -0x102c 0x6256 -0x102c 0x6257 -0x102c 0x6258 -0x102c 0x6259 -0x102c 0x625a -0x102c 0x625b -0x102c 0x625c -0x102c 0x625d -0x102c 0x625e -0x102c 0x625f -0x102c 0x6260 -0x102c 0x6261 -0x102c 0x6262 -0x102c 0x6263 -0x102c 0x6264 -0x102c 0x6265 -0x102c 0x6266 -0x102c 0x6267 -0x102c 0x6268 -0x102c 0x6269 - -The following image sensors are supported: - -Model Manufacturer ------ ------------ -TAS5130D1B Taiwan Advanced Sensor Corporation - -All the available control settings of each image sensor are supported through -the V4L2 interface. - - -10. Notes for V4L2 application developers -========================================= -This driver follows the V4L2 API specifications. In particular, it enforces two -rules: - -- exactly one I/O method, either "mmap" or "read", is associated with each -file descriptor. Once it is selected, the application must close and reopen the -device to switch to the other I/O method; - -- although it is not mandatory, previously mapped buffer memory should always -be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. -The same number of buffers as before will be allocated again to match the size -of the new video frames, so you have to map the buffers again before any I/O -attempts on them. - -Consistently with the hardware limits, this driver also supports image -downscaling with arbitrary scaling factors from 1 and 2 in both directions. -However, the V4L2 API specifications don't correctly define how the scaling -factor can be chosen arbitrarily by the "negotiation" of the "source" and -"target" rectangles. To work around this flaw, we have added the convention -that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the -scaling factor is restored to 1. - -This driver supports two different video formats: the first one is the "8-bit -Sequential Bayer" format and can be used to obtain uncompressed video data -from the device through the current I/O method, while the second one provides -"raw" compressed video data (without frame headers not related to the -compressed data). The current compression quality may vary from 0 to 1 and can -be selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP -V4L2 ioctl's. - - -11. Contact information -======================= -The author may be contacted by e-mail at . - -GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is -'FCE635A4'; the public 1024-bit key should be available at any keyserver; -the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. diff --git a/Documentation/usb/ibmcam.txt b/Documentation/usb/ibmcam.txt deleted file mode 100644 index c25003644131..000000000000 --- a/Documentation/usb/ibmcam.txt +++ /dev/null @@ -1,324 +0,0 @@ -README for Linux device driver for the IBM "C-It" USB video camera - -INTRODUCTION: - -This driver does not use all features known to exist in -the IBM camera. However most of needed features work well. - -This driver was developed using logs of observed USB traffic -which was produced by standard Windows driver (c-it98.sys). -I did not have data sheets from Xirlink. - -Video formats: - 128x96 [model 1] - 176x144 - 320x240 [model 2] - 352x240 [model 2] - 352x288 -Frame rate: 3 - 30 frames per second (FPS) -External interface: USB -Internal interface: Video For Linux (V4L) -Supported controls: -- by V4L: Contrast, Brightness, Color, Hue -- by driver options: frame rate, lighting conditions, video format, - default picture settings, sharpness. - -SUPPORTED CAMERAS: - -Xirlink "C-It" camera, also known as "IBM PC Camera". -The device uses proprietary ASIC (and compression method); -it is manufactured by Xirlink. See http://www.xirlink.com/ -(renamed to http://www.veo.com), http://www.ibmpccamera.com, -or http://www.c-itnow.com/ for details and pictures. - -This very chipset ("X Chip", as marked at the factory) -is used in several other cameras, and they are supported -as well: - -- IBM NetCamera -- Veo Stingray - -The Linux driver was developed with camera with following -model number (or FCC ID): KSX-XVP510. This camera has three -interfaces, each with one endpoint (control, iso, iso). This -type of cameras is referred to as "model 1". These cameras are -no longer manufactured. - -Xirlink now manufactures new cameras which are somewhat different. -In particular, following models [FCC ID] belong to that category: - -XVP300 [KSX-X9903] -XVP600 [KSX-X9902] -XVP610 [KSX-X9902] - -(see http://www.xirlink.com/ibmpccamera/ for updates, they refer -to these new cameras by Windows driver dated 12-27-99, v3005 BETA) -These cameras have two interfaces, one endpoint in each (iso, bulk). -Such type of cameras is referred to as "model 2". They are supported -(with exception of 352x288 native mode). - -Some IBM NetCameras (Model 4) are made to generate only compressed -video streams. This is great for performance, but unfortunately -nobody knows how to decompress the stream :-( Therefore, these -cameras are *unsupported* and if you try to use one of those, all -you get is random colored horizontal streaks, not the image! -If you have one of those cameras, you probably should return it -to the store and get something that is supported. - -Tell me more about all that "model" business --------------------------------------------- - -I just invented model numbers to uniquely identify flavors of the -hardware/firmware that were sold. It was very confusing to use -brand names or some other internal numbering schemes. So I found -by experimentation that all Xirlink chipsets fall into four big -classes, and I called them "models". Each model is programmed in -its own way, and each model sends back the video in its own way. - -Quirks of Model 2 cameras: -------------------------- - -Model 2 does not have hardware contrast control. Corresponding V4L -control is implemented in software, which is not very nice to your -CPU, but at least it works. - -This driver provides 352x288 mode by switching the camera into -quasi-352x288 RGB mode (800 Kbits per frame) essentially limiting -this mode to 10 frames per second or less, in ideal conditions on -the bus (USB is shared, after all). The frame rate -has to be programmed very conservatively. Additional concern is that -frame rate depends on brightness setting; therefore the picture can -be good at one brightness and broken at another! I did not want to fix -the frame rate at slowest setting, but I had to move it pretty much down -the scale (so that framerate option barely matters). I also noticed that -camera after first powering up produces frames slightly faster than during -consecutive uses. All this means that if you use 352x288 (which is -default), be warned - you may encounter broken picture on first connect; -try to adjust brightness - brighter image is slower, so USB will be able -to send all data. However if you regularly use Model 2 cameras you may -prefer 176x144 which makes perfectly good I420, with no scaling and -lesser demands on USB (300 Kbits per second, or 26 frames per second). - -Another strange effect of 352x288 mode is the fine vertical grid visible -on some colored surfaces. I am sure it is caused by me not understanding -what the camera is trying to say. Blame trade secrets for that. - -The camera that I had also has a hardware quirk: if disconnected, -it needs few minutes to "relax" before it can be plugged in again -(poorly designed USB processor reset circuit?) - -[Veo Stingray with Product ID 0x800C is also Model 2, but I haven't -observed this particular flaw in it.] - -Model 2 camera can be programmed for very high sensitivity (even starlight -may be enough), this makes it convenient for tinkering with. The driver -code has enough comments to help a programmer to tweak the camera -as s/he feels necessary. - -WHAT YOU NEED: - -- A supported IBM PC (C-it) camera (model 1 or 2) - -- A Linux box with USB support (2.3/2.4; 2.2 w/backport may work) - -- A Video4Linux compatible frame grabber program such as xawtv. - -HOW TO COMPILE THE DRIVER: - -You need to compile the driver only if you are a developer -or if you want to make changes to the code. Most distributions -precompile all modules, so you can go directly to the next -section "HOW TO USE THE DRIVER". - -The ibmcam driver uses usbvideo helper library (module), -so if you are studying the ibmcam code you will be led there. - -The driver itself consists of only one file in usb/ directory: -ibmcam.c. This file is included into the Linux kernel build -process if you configure the kernel for CONFIG_USB_IBMCAM. -Run "make xconfig" and in USB section you will find the IBM -camera driver. Select it, save the configuration and recompile. - -HOW TO USE THE DRIVER: - -I recommend to compile driver as a module. This gives you an -easier access to its configuration. The camera has many more -settings than V4L can operate, so some settings are done using -module options. - -To begin with, on most modern Linux distributions the driver -will be automatically loaded whenever you plug the supported -camera in. Therefore, you don't need to do anything. However -if you want to experiment with some module parameters then -you can load and unload the driver manually, with camera -plugged in or unplugged. - -Typically module is installed with command 'modprobe', like this: - -# modprobe ibmcam framerate=1 - -Alternatively you can use 'insmod' in similar fashion: - -# insmod /lib/modules/2.x.y/usb/ibmcam.o framerate=1 - -Module can be inserted with camera connected or disconnected. - -The driver can have options, though some defaults are provided. - -Driver options: (* indicates that option is model-dependent) - -Name Type Range [default] Example --------------- -------------- -------------- ------------------ -debug Integer 0-9 [0] debug=1 -flags Integer 0-0xFF [0] flags=0x0d -framerate Integer 0-6 [2] framerate=1 -hue_correction Integer 0-255 [128] hue_correction=115 -init_brightness Integer 0-255 [128] init_brightness=100 -init_contrast Integer 0-255 [192] init_contrast=200 -init_color Integer 0-255 [128] init_color=130 -init_hue Integer 0-255 [128] init_hue=115 -lighting Integer 0-2* [1] lighting=2 -sharpness Integer 0-6* [4] sharpness=3 -size Integer 0-2* [2] size=1 - -Options for Model 2 only: - -Name Type Range [default] Example --------------- -------------- -------------- ------------------ -init_model2_rg Integer 0..255 [0x70] init_model2_rg=128 -init_model2_rg2 Integer 0..255 [0x2f] init_model2_rg2=50 -init_model2_sat Integer 0..255 [0x34] init_model2_sat=65 -init_model2_yb Integer 0..255 [0xa0] init_model2_yb=200 - -debug You don't need this option unless you are a developer. - If you are a developer then you will see in the code - what values do what. 0=off. - -flags This is a bit mask, and you can combine any number of - bits to produce what you want. Usually you don't want - any of extra features this option provides: - - FLAGS_RETRY_VIDIOCSYNC 1 This bit allows to retry failed - VIDIOCSYNC ioctls without failing. - Will work with xawtv, will not - with xrealproducer. Default is - not set. - FLAGS_MONOCHROME 2 Activates monochrome (b/w) mode. - FLAGS_DISPLAY_HINTS 4 Shows colored pixels which have - magic meaning to developers. - FLAGS_OVERLAY_STATS 8 Shows tiny numbers on screen, - useful only for debugging. - FLAGS_FORCE_TESTPATTERN 16 Shows blue screen with numbers. - FLAGS_SEPARATE_FRAMES 32 Shows each frame separately, as - it was received from the camera. - Default (not set) is to mix the - preceding frame in to compensate - for occasional loss of Isoc data - on high frame rates. - FLAGS_CLEAN_FRAMES 64 Forces "cleanup" of each frame - prior to use; relevant only if - FLAGS_SEPARATE_FRAMES is set. - Default is not to clean frames, - this is a little faster but may - produce flicker if frame rate is - too high and Isoc data gets lost. - FLAGS_NO_DECODING 128 This flag turns the video stream - decoder off, and dumps the raw - Isoc data from the camera into - the reading process. Useful to - developers, but not to users. - -framerate This setting controls frame rate of the camera. This is - an approximate setting (in terms of "worst" ... "best") - because camera changes frame rate depending on amount - of light available. Setting 0 is slowest, 6 is fastest. - Beware - fast settings are very demanding and may not - work well with all video sizes. Be conservative. - -hue_correction This highly optional setting allows to adjust the - hue of the image in a way slightly different from - what usual "hue" control does. Both controls affect - YUV colorspace: regular "hue" control adjusts only - U component, and this "hue_correction" option similarly - adjusts only V component. However usually it is enough - to tweak only U or V to compensate for colored light or - color temperature; this option simply allows more - complicated correction when and if it is necessary. - -init_brightness These settings specify _initial_ values which will be -init_contrast used to set up the camera. If your V4L application has -init_color its own controls to adjust the picture then these -init_hue controls will be used too. These options allow you to - preconfigure the camera when it gets connected, before - any V4L application connects to it. Good for webcams. - -init_model2_rg These initial settings alter color balance of the -init_model2_rg2 camera on hardware level. All four settings may be used -init_model2_sat to tune the camera to specific lighting conditions. These -init_model2_yb settings only apply to Model 2 cameras. - -lighting This option selects one of three hardware-defined - photosensitivity settings of the camera. 0=bright light, - 1=Medium (default), 2=Low light. This setting affects - frame rate: the dimmer the lighting the lower the frame - rate (because longer exposition time is needed). The - Model 2 cameras allow values more than 2 for this option, - thus enabling extremely high sensitivity at cost of frame - rate, color saturation and imaging sensor noise. - -sharpness This option controls smoothing (noise reduction) - made by camera. Setting 0 is most smooth, setting 6 - is most sharp. Be aware that CMOS sensor used in the - camera is pretty noisy, so if you choose 6 you will - be greeted with "snowy" image. Default is 4. Model 2 - cameras do not support this feature. - -size This setting chooses one of several image sizes that are - supported by this driver. Cameras may support more, but - it's difficult to reverse-engineer all formats. - Following video sizes are supported: - - size=0 128x96 (Model 1 only) - size=1 160x120 - size=2 176x144 - size=3 320x240 (Model 2 only) - size=4 352x240 (Model 2 only) - size=5 352x288 - size=6 640x480 (Model 3 only) - - The 352x288 is the native size of the Model 1 sensor - array, so it's the best resolution the camera can - yield. The best resolution of Model 2 is 176x144, and - larger images are produced by stretching the bitmap. - Model 3 has sensor with 640x480 grid, and it works too, - but the frame rate will be exceptionally low (1-2 FPS); - it may be still OK for some applications, like security. - Choose the image size you need. The smaller image can - support faster frame rate. Default is 352x288. - -For more information and the Troubleshooting FAQ visit this URL: - - http://www.linux-usb.org/ibmcam/ - -WHAT NEEDS TO BE DONE: - -- The button on the camera is not used. I don't know how to get to it. - I know now how to read button on Model 2, but what to do with it? - -- Camera reports its status back to the driver; however I don't know - what returned data means. If camera fails at some initialization - stage then something should be done, and I don't do that because - I don't even know that some command failed. This is mostly Model 1 - concern because Model 2 uses different commands which do not return - status (and seem to complete successfully every time). - -- Some flavors of Model 4 NetCameras produce only compressed video - streams, and I don't know how to decode them. - -CREDITS: - -The code is based in no small part on the CPiA driver by Johannes Erdfelt, -Randy Dunlap, and others. Big thanks to them for their pioneering work on that -and the USB stack. - -I also thank John Lightsey for his donation of the Veo Stingray camera. diff --git a/Documentation/usb/ov511.txt b/Documentation/usb/ov511.txt deleted file mode 100644 index a7fc0432bff1..000000000000 --- a/Documentation/usb/ov511.txt +++ /dev/null @@ -1,289 +0,0 @@ -------------------------------------------------------------------------------- -Readme for Linux device driver for the OmniVision OV511 USB to camera bridge IC -------------------------------------------------------------------------------- - -Author: Mark McClelland -Homepage: http://alpha.dyndns.org/ov511 - -INTRODUCTION: - -This is a driver for the OV511, a USB-only chip used in many "webcam" devices. -Any camera using the OV511/OV511+ and the OV6620/OV7610/20/20AE should work. -Video capture devices that use the Philips SAA7111A decoder also work. It -supports streaming and capture of color or monochrome video via the Video4Linux -API. Most V4L apps are compatible with it. Most resolutions with a width and -height that are a multiple of 8 are supported. - -If you need more information, please visit the OV511 homepage at the above URL. - -WHAT YOU NEED: - -- If you want to help with the development, get the chip's specification docs at - http://www.ovt.com/omniusbp.html - -- A Video4Linux compatible frame grabber program (I recommend vidcat and xawtv) - vidcat is part of the w3cam package: http://mpx.freeshell.net/ - xawtv is available at: http://linux.bytesex.org/xawtv/ - -HOW TO USE IT: - -Note: These are simplified instructions. For complete instructions see: - http://alpha.dyndns.org/ov511/install.html - -You must have first compiled USB support, support for your specific USB host -controller (UHCI or OHCI), and Video4Linux support for your kernel (I recommend -making them modules.) Make sure "Enforce bandwidth allocation" is NOT enabled. - -Next, (as root): - - modprobe usbcore - modprobe usb-uhci modprobe usb-ohci - modprobe videodev - modprobe ov511 - -If it is not already there (it usually is), create the video device: - - mknod /dev/video0 c 81 0 - -Optionally, symlink /dev/video to /dev/video0 - -You will have to set permissions on this device to allow you to read/write -from it: - - chmod 666 /dev/video - chmod 666 /dev/video0 (if necessary) - -Now you are ready to run a video app! Both vidcat and xawtv work well for me -at 640x480. - -[Using vidcat:] - - vidcat -s 640x480 -p c > test.jpg - xview test.jpg - -[Using xawtv:] - -From the main xawtv directory: - - make clean - ./configure - make - make install - -Now you should be able to run xawtv. Right click for the options dialog. - -MODULE PARAMETERS: - - You can set these with: insmod ov511 NAME=VALUE - There is currently no way to set these on a per-camera basis. - - NAME: autobright - TYPE: integer (Boolean) - DEFAULT: 1 - DESC: Brightness is normally under automatic control and can't be set - manually by the video app. Set to 0 for manual control. - - NAME: autogain - TYPE: integer (Boolean) - DEFAULT: 1 - DESC: Auto Gain Control enable. This feature is not yet implemented. - - NAME: autoexp - TYPE: integer (Boolean) - DEFAULT: 1 - DESC: Auto Exposure Control enable. This feature is not yet implemented. - - NAME: debug - TYPE: integer (0-6) - DEFAULT: 3 - DESC: Sets the threshold for printing debug messages. The higher the value, - the more is printed. The levels are cumulative, and are as follows: - 0=no debug messages - 1=init/detection/unload and other significant messages - 2=some warning messages - 3=config/control function calls - 4=most function calls and data parsing messages - 5=highly repetitive mesgs - - NAME: snapshot - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: Set to 1 to enable snapshot mode. read()/VIDIOCSYNC will block until - the snapshot button is pressed. Note: enabling this mode disables - /proc/video/ov511//button - - NAME: cams - TYPE: integer (1-4 for OV511, 1-31 for OV511+) - DEFAULT: 1 - DESC: Number of cameras allowed to stream simultaneously on a single bus. - Values higher than 1 reduce the data rate of each camera, allowing two - or more to be used at once. If you have a complicated setup involving - both OV511 and OV511+ cameras, trial-and-error may be necessary for - finding the optimum setting. - - NAME: compress - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: Set this to 1 to turn on the camera's compression engine. This can - potentially increase the frame rate at the expense of quality, if you - have a fast CPU. You must load the proper compression module for your - camera before starting your application (ov511_decomp or ov518_decomp). - - NAME: testpat - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: This configures the camera's sensor to transmit a colored test-pattern - instead of an image. This does not work correctly yet. - - NAME: dumppix - TYPE: integer (0-2) - DEFAULT: 0 - DESC: Dumps raw pixel data and skips post-processing and format conversion. - It is for debugging purposes only. Options are: - 0: Disable (default) - 1: Dump raw data from camera, excluding headers and trailers - 2: Dumps data exactly as received from camera - - NAME: led - TYPE: integer (0-2) - DEFAULT: 1 (Always on) - DESC: Controls whether the LED (the little light) on the front of the camera - is always off (0), always on (1), or only on when driver is open (2). - This is not supported with the OV511, and might only work with certain - cameras (ones that actually have the LED wired to the control pin, and - not just hard-wired to be on all the time). - - NAME: dump_bridge - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: Dumps the bridge (OV511[+] or OV518[+]) register values to the system - log. Only useful for serious debugging/development purposes. - - NAME: dump_sensor - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: Dumps the sensor register values to the system log. Only useful for - serious debugging/development purposes. - - NAME: printph - TYPE: integer (Boolean) - DEFAULT: 0 - DESC: Setting this to 1 will dump the first 12 bytes of each isoc frame. This - is only useful if you are trying to debug problems with the isoc data - stream (i.e.: camera initializes, but vidcat hangs until Ctrl-C). Be - warned that this dumps a large number of messages to your kernel log. - - NAME: phy, phuv, pvy, pvuv, qhy, qhuv, qvy, qvuv - TYPE: integer (0-63 for phy and phuv, 0-255 for rest) - DEFAULT: OV511 default values - DESC: These are registers 70h - 77h of the OV511, which control the - prediction ranges and quantization thresholds of the compressor, for - the Y and UV channels in the horizontal and vertical directions. See - the OV511 or OV511+ data sheet for more detailed descriptions. These - normally do not need to be changed. - - NAME: lightfreq - TYPE: integer (0, 50, or 60) - DEFAULT: 0 (use sensor default) - DESC: Sets the sensor to match your lighting frequency. This can reduce the - appearance of "banding", i.e. horizontal lines or waves of light and - dark that are often caused by artificial lighting. Valid values are: - 0 - Use default (depends on sensor, most likely 60 Hz) - 50 - For European and Asian 50 Hz power - 60 - For American 60 Hz power - - NAME: bandingfilter - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Enables the sensorīs banding filter exposure algorithm. This reduces - or stabilizes the "banding" caused by some artificial light sources - (especially fluorescent). You might have to set lightfreq correctly for - this to work right. As an added bonus, this sometimes makes it - possible to capture your monitorīs output. - - NAME: fastset - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Allows picture settings (brightness, contrast, color, and hue) to take - effect immediately, even in the middle of a frame. This reduces the - time to change settings, but can ruin frames during the change. Only - affects OmniVision sensors. - - NAME: force_palette - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Forces the palette (color format) to a specific value. If an - application requests a different palette, it will be rejected, thereby - forcing it to try others until it succeeds. This is useful for forcing - greyscale mode with a color camera, for example. Supported modes are: - 0 (Allows all the following formats) - 1 VIDEO_PALETTE_GREY (Linear greyscale) - 10 VIDEO_PALETTE_YUV420 (YUV 4:2:0 Planar) - 15 VIDEO_PALETTE_YUV420P (YUV 4:2:0 Planar, same as 10) - - NAME: backlight - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Setting this flag changes the exposure algorithm for OmniVision sensors - such that objects in the camera's view (i.e. your head) can be clearly - seen when they are illuminated from behind. It reduces or eliminates - the sensor's auto-exposure function, so it should only be used when - needed. Additionally, it is only supported with the OV6620 and OV7620. - - NAME: unit_video - TYPE: Up to 16 comma-separated integers - DEFAULT: 0,0,0... (automatically assign the next available minor(s)) - DESC: You can specify up to 16 minor numbers to be assigned to ov511 devices. - For example, "unit_video=1,3" will make the driver use /dev/video1 and - /dev/video3 for the first two devices it detects. Additional devices - will be assigned automatically starting at the first available device - node (/dev/video0 in this case). Note that you cannot specify 0 as a - minor number. This feature requires kernel version 2.4.5 or higher. - - NAME: remove_zeros - TYPE: integer (Boolean) - DEFAULT: 0 (do not skip any incoming data) - DESC: Setting this to 1 will remove zero-padding from incoming data. This - will compensate for the blocks of corruption that can appear when the - camera cannot keep up with the speed of the USB bus (eg. at low frame - resolutions). This feature is always enabled when compression is on. - - NAME: mirror - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Setting this to 1 will reverse ("mirror") the image horizontally. This - might be necessary if your camera has a custom lens assembly. This has - no effect with video capture devices. - - NAME: ov518_color - TYPE: integer (Boolean) - DEFAULT: 0 (off) - DESC: Enable OV518 color support. This is off by default since it doesn't - work most of the time. If you want to try it, you must also load - ov518_decomp with the "nouv=0" parameter. If you get improper colors or - diagonal lines through the image, restart your video app and try again. - Repeat as necessary. - -WORKING FEATURES: - o Color streaming/capture at most widths and heights that are multiples of 8. - o Monochrome (use force_palette=1 to enable) - o Setting/getting of saturation, contrast, brightness, and hue (only some of - them work the OV7620 and OV7620AE) - o /proc status reporting - o SAA7111A video capture support at 320x240 and 640x480 - o Compression support - o SMP compatibility - -HOW TO CONTACT ME: - -You can email me at mark@alpha.dyndns.org . Please prefix the subject line -with "OV511: " so that I am certain to notice your message. - -CREDITS: - -The code is based in no small part on the CPiA driver by Johannes Erdfelt, -Randy Dunlap, and others. Big thanks to them for their pioneering work on that -and the USB stack. Thanks to Bret Wallach for getting camera reg IO, ISOC, and -image capture working. Thanks to Orion Sky Lawlor, Kevin Moore, and Claudio -Matsuoka for their work as well. - diff --git a/Documentation/usb/se401.txt b/Documentation/usb/se401.txt deleted file mode 100644 index 7b9d1c960a10..000000000000 --- a/Documentation/usb/se401.txt +++ /dev/null @@ -1,54 +0,0 @@ -Linux driver for SE401 based USB cameras - -Copyright, 2001, Jeroen Vreeken - - -INTRODUCTION: - -The SE401 chip is the used in low-cost usb webcams. -It is produced by Endpoints Inc. (www.endpoints.com). -It interfaces directly to a cmos image sensor and USB. The only other major -part in a se401 based camera is a dram chip. - -The following cameras are known to work with this driver: - -Aox se401 (non-branded) cameras -Philips PVCV665 USB VGA webcam 'Vesta Fun' -Kensington VideoCAM PC Camera Model 67014 -Kensington VideoCAM PC Camera Model 67015 -Kensington VideoCAM PC Camera Model 67016 -Kensington VideoCAM PC Camera Model 67017 - - -WHAT YOU NEED: - -- USB support -- VIDEO4LINUX support - -More information about USB support for linux can be found at: -http://www.linux-usb.org - - -MODULE OPTIONS: - -When the driver is compiled as a module you can also use the 'flickerless' -option. With it exposure is limited to values that do not interfere with the -net frequency. Valid options for this option are 0, 50 and 60. (0=disable, -50=50hz, 60=60hz) - - -KNOWN PROBLEMS: - -The driver works fine with the usb-ohci and uhci host controller drivers, -the default settings also work with usb-uhci. But sending more than one bulk -transfer at a time with usb-uhci doesn't work yet. -Users of usb-ohci and uhci can safely enlarge SE401_NUMSBUF in se401.h in -order to increase the throughput (and thus framerate). - - -HELP: - -The latest info on this driver can be found at: -http://www.chello.nl/~j.vreeken/se401/ -And questions to me can be send to: -pe1rxq@amsat.org diff --git a/Documentation/usb/sn9c102.txt b/Documentation/usb/sn9c102.txt deleted file mode 100644 index b957beae5607..000000000000 --- a/Documentation/usb/sn9c102.txt +++ /dev/null @@ -1,518 +0,0 @@ - - SN9C10x PC Camera Controllers - Driver for Linux - ============================= - - - Documentation - - - -Index -===== -1. Copyright -2. Disclaimer -3. License -4. Overview and features -5. Module dependencies -6. Module loading -7. Module parameters -8. Optional device control through "sysfs" -9. Supported devices -10. Notes for V4L2 application developers -11. Video frame formats -12. Contact information -13. Credits - - -1. Copyright -============ -Copyright (C) 2004-2006 by Luca Risolia - - -2. Disclaimer -============= -SONiX is a trademark of SONiX Technology Company Limited, inc. -This software is not sponsored or developed by SONiX. - - -3. License -========== -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program; if not, write to the Free Software -Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - -4. Overview and features -======================== -This driver attempts to support the video interface of the devices mounting the -SONiX SN9C101, SN9C102 and SN9C103 PC Camera Controllers. - -It's worth to note that SONiX has never collaborated with the author during the -development of this project, despite several requests for enough detailed -specifications of the register tables, compression engine and video data format -of the above chips. Nevertheless, these informations are no longer necessary, -becouse all the aspects related to these chips are known and have been -described in detail in this documentation. - -The driver relies on the Video4Linux2 and USB core modules. It has been -designed to run properly on SMP systems as well. - -The latest version of the SN9C10x driver can be found at the following URL: -http://www.linux-projects.org/ - -Some of the features of the driver are: - -- full compliance with the Video4Linux2 API (see also "Notes for V4L2 - application developers" paragraph); -- available mmap or read/poll methods for video streaming through isochronous - data transfers; -- automatic detection of image sensor; -- support for built-in microphone interface; -- support for any window resolutions and optional panning within the maximum - pixel area of image sensor; -- image downscaling with arbitrary scaling factors from 1, 2 and 4 in both - directions (see "Notes for V4L2 application developers" paragraph); -- two different video formats for uncompressed or compressed data in low or - high compression quality (see also "Notes for V4L2 application developers" - and "Video frame formats" paragraphs); -- full support for the capabilities of many of the possible image sensors that - can be connected to the SN9C10x bridges, including, for istance, red, green, - blue and global gain adjustments and exposure (see "Supported devices" - paragraph for details); -- use of default color settings for sunlight conditions; -- dynamic I/O interface for both SN9C10x and image sensor control and - monitoring (see "Optional device control through 'sysfs'" paragraph); -- dynamic driver control thanks to various module parameters (see "Module - parameters" paragraph); -- up to 64 cameras can be handled at the same time; they can be connected and - disconnected from the host many times without turning off the computer, if - the system supports hotplugging; -- no known bugs. - - -5. Module dependencies -====================== -For it to work properly, the driver needs kernel support for Video4Linux and -USB. - -The following options of the kernel configuration file must be enabled and -corresponding modules must be compiled: - - # Multimedia devices - # - CONFIG_VIDEO_DEV=m - -To enable advanced debugging functionality on the device through /sysfs: - - # Multimedia devices - # - CONFIG_VIDEO_ADV_DEBUG=y - - # USB support - # - CONFIG_USB=m - -In addition, depending on the hardware being used, the modules below are -necessary: - - # USB Host Controller Drivers - # - CONFIG_USB_EHCI_HCD=m - CONFIG_USB_UHCI_HCD=m - CONFIG_USB_OHCI_HCD=m - -The SN9C103 controller also provides a built-in microphone interface. It is -supported by the USB Audio driver thanks to the ALSA API: - - # Sound - # - CONFIG_SOUND=y - - # Advanced Linux Sound Architecture - # - CONFIG_SND=m - - # USB devices - # - CONFIG_SND_USB_AUDIO=m - -And finally: - - # USB Multimedia devices - # - CONFIG_USB_SN9C102=m - - -6. Module loading -================= -To use the driver, it is necessary to load the "sn9c102" module into memory -after every other module required: "videodev", "usbcore" and, depending on -the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". - -Loading can be done as shown below: - - [root@localhost home]# modprobe sn9c102 - -At this point the devices should be recognized. You can invoke "dmesg" to -analyze kernel messages and verify that the loading process has gone well: - - [user@localhost home]$ dmesg - - -7. Module parameters -==================== -Module parameters are listed below: -------------------------------------------------------------------------------- -Name: video_nr -Type: short array (min = 0, max = 64) -Syntax: <-1|n[,...]> -Description: Specify V4L2 minor mode number: - -1 = use next available - n = use minor number n - You can specify up to 64 cameras this way. - For example: - video_nr=-1,2,-1 would assign minor number 2 to the second - recognized camera and use auto for the first one and for every - other camera. -Default: -1 -------------------------------------------------------------------------------- -Name: force_munmap -Type: bool array (min = 0, max = 64) -Syntax: <0|1[,...]> -Description: Force the application to unmap previously mapped buffer memory - before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not - all the applications support this feature. This parameter is - specific for each detected camera. - 0 = do not force memory unmapping - 1 = force memory unmapping (save memory) -Default: 0 -------------------------------------------------------------------------------- -Name: frame_timeout -Type: uint array (min = 0, max = 64) -Syntax: -Description: Timeout for a video frame in seconds. This parameter is - specific for each detected camera. This parameter can be - changed at runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- -Name: debug -Type: ushort -Syntax: -Description: Debugging information level, from 0 to 3: - 0 = none (use carefully) - 1 = critical errors - 2 = significant informations - 3 = more verbose messages - Level 3 is useful for testing only, when only one device - is used. It also shows some more informations about the - hardware being detected. This parameter can be changed at - runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- - - -8. Optional device control through "sysfs" [1] -========================================== -If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, -it is possible to read and write both the SN9C10x and the image sensor -registers by using the "sysfs" filesystem interface. - -Every time a supported device is recognized, a write-only file named "green" is -created in the /sys/class/video4linux/videoX directory. You can set the green -channel's gain by writing the desired value to it. The value may range from 0 -to 15 for SN9C101 or SN9C102 bridges, from 0 to 127 for SN9C103 bridges. -Similarly, only for SN9C103 controllers, blue and red gain control files are -available in the same directory, for which accepted values may range from 0 to -127. - -There are other four entries in the directory above for each registered camera: -"reg", "val", "i2c_reg" and "i2c_val". The first two files control the -SN9C10x bridge, while the other two control the sensor chip. "reg" and -"i2c_reg" hold the values of the current register index where the following -reading/writing operations are addressed at through "val" and "i2c_val". Their -use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not -be created if the sensor does not actually support the standard I2C protocol or -its registers are not 8-bit long. Also, remember that you must be logged in as -root before writing to them. - -As an example, suppose we were to want to read the value contained in the -register number 1 of the sensor register table - which is usually the product -identifier - of the camera registered as "/dev/video0": - - [root@localhost #] cd /sys/class/video4linux/video0 - [root@localhost #] echo 1 > i2c_reg - [root@localhost #] cat i2c_val - -Note that "cat" will fail if sensor registers cannot be read. - -Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2: - - [root@localhost #] echo 0x11 > reg - [root@localhost #] echo 2 > val - -Note that the SN9C10x always returns 0 when some of its registers are read. -To avoid race conditions, all the I/O accesses to the above files are -serialized. - -The sysfs interface also provides the "frame_header" entry, which exports the -frame header of the most recent requested and captured video frame. The header -is always 18-bytes long and is appended to every video frame by the SN9C10x -controllers. As an example, this additional information can be used by the user -application for implementing auto-exposure features via software. - -The following table describes the frame header: - -Byte # Value Description ------- ----- ----------- -0x00 0xFF Frame synchronisation pattern. -0x01 0xFF Frame synchronisation pattern. -0x02 0x00 Frame synchronisation pattern. -0x03 0xC4 Frame synchronisation pattern. -0x04 0xC4 Frame synchronisation pattern. -0x05 0x96 Frame synchronisation pattern. -0x06 0xXX Unknown meaning. The exact value depends on the chip; - possible values are 0x00, 0x01 and 0x20. -0x07 0xXX Variable value, whose bits are ff00uzzc, where ff is a - frame counter, u is unknown, zz is a size indicator - (00 = VGA, 01 = SIF, 10 = QSIF) and c stands for - "compression enabled" (1 = yes, 0 = no). -0x08 0xXX Brightness sum inside Auto-Exposure area (low-byte). -0x09 0xXX Brightness sum inside Auto-Exposure area (high-byte). - For a pure white image, this number will be equal to 500 - times the area of the specified AE area. For images - that are not pure white, the value scales down according - to relative whiteness. -0x0A 0xXX Brightness sum outside Auto-Exposure area (low-byte). -0x0B 0xXX Brightness sum outside Auto-Exposure area (high-byte). - For a pure white image, this number will be equal to 125 - times the area outside of the specified AE area. For - images that are not pure white, the value scales down - according to relative whiteness. - according to relative whiteness. - -The following bytes are used by the SN9C103 bridge only: - -0x0C 0xXX Unknown meaning -0x0D 0xXX Unknown meaning -0x0E 0xXX Unknown meaning -0x0F 0xXX Unknown meaning -0x10 0xXX Unknown meaning -0x11 0xXX Unknown meaning - -The AE area (sx, sy, ex, ey) in the active window can be set by programming the -registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C10x controllers, where one unit -corresponds to 32 pixels. - -[1] Part of the meaning of the frame header has been documented by Bertrik - Sikken. - - -9. Supported devices -==================== -None of the names of the companies as well as their products will be mentioned -here. They have never collaborated with the author, so no advertising. - -From the point of view of a driver, what unambiguously identify a device are -its vendor and product USB identifiers. Below is a list of known identifiers of -devices mounting the SN9C10x PC camera controllers: - -Vendor ID Product ID ---------- ---------- -0x0c45 0x6001 -0x0c45 0x6005 -0x0c45 0x6007 -0x0c45 0x6009 -0x0c45 0x600d -0x0c45 0x6024 -0x0c45 0x6025 -0x0c45 0x6028 -0x0c45 0x6029 -0x0c45 0x602a -0x0c45 0x602b -0x0c45 0x602c -0x0c45 0x602d -0x0c45 0x602e -0x0c45 0x6030 -0x0c45 0x6080 -0x0c45 0x6082 -0x0c45 0x6083 -0x0c45 0x6088 -0x0c45 0x608a -0x0c45 0x608b -0x0c45 0x608c -0x0c45 0x608e -0x0c45 0x608f -0x0c45 0x60a0 -0x0c45 0x60a2 -0x0c45 0x60a3 -0x0c45 0x60a8 -0x0c45 0x60aa -0x0c45 0x60ab -0x0c45 0x60ac -0x0c45 0x60ae -0x0c45 0x60af -0x0c45 0x60b0 -0x0c45 0x60b2 -0x0c45 0x60b3 -0x0c45 0x60b8 -0x0c45 0x60ba -0x0c45 0x60bb -0x0c45 0x60bc -0x0c45 0x60be - -The list above does not imply that all those devices work with this driver: up -until now only the ones that mount the following image sensors are supported; -kernel messages will always tell you whether this is the case: - -Model Manufacturer ------ ------------ -HV7131D Hynix Semiconductor, Inc. -MI-0343 Micron Technology, Inc. -OV7630 OmniVision Technologies, Inc. -PAS106B PixArt Imaging, Inc. -PAS202BCA PixArt Imaging, Inc. -PAS202BCB PixArt Imaging, Inc. -TAS5110C1B Taiwan Advanced Sensor Corporation -TAS5130D1B Taiwan Advanced Sensor Corporation - -All the available control settings of each image sensor are supported through -the V4L2 interface. - -Donations of new models for further testing and support would be much -appreciated. Non-available hardware will not be supported by the author of this -driver. - - -10. Notes for V4L2 application developers -========================================= -This driver follows the V4L2 API specifications. In particular, it enforces two -rules: - -- exactly one I/O method, either "mmap" or "read", is associated with each -file descriptor. Once it is selected, the application must close and reopen the -device to switch to the other I/O method; - -- although it is not mandatory, previously mapped buffer memory should always -be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. -The same number of buffers as before will be allocated again to match the size -of the new video frames, so you have to map the buffers again before any I/O -attempts on them. - -Consistently with the hardware limits, this driver also supports image -downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions. -However, the V4L2 API specifications don't correctly define how the scaling -factor can be chosen arbitrarily by the "negotiation" of the "source" and -"target" rectangles. To work around this flaw, we have added the convention -that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the -scaling factor is restored to 1. - -This driver supports two different video formats: the first one is the "8-bit -Sequential Bayer" format and can be used to obtain uncompressed video data -from the device through the current I/O method, while the second one provides -"raw" compressed video data (without frame headers not related to the -compressed data). The compression quality may vary from 0 to 1 and can be -selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 -ioctl's. For maximum flexibility, both the default active video format and the -default compression quality depend on how the image sensor being used is -initialized (as described in the documentation of the API for the image sensors -supplied by this driver). - - -11. Video frame formats [1] -======================= -The SN9C10x PC Camera Controllers can send images in two possible video -formats over the USB: either native "Sequential RGB Bayer" or Huffman -compressed. The latter is used to achieve high frame rates. The current video -format may be selected or queried from the user application by calling the -VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 API -specifications. - -The name "Sequential Bayer" indicates the organization of the red, green and -blue pixels in one video frame. Each pixel is associated with a 8-bit long -value and is disposed in memory according to the pattern shown below: - -B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] -G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] -... -... B[(n-1)(m-2)] G[(n-1)(m-1)] -... G[n(m-2)] R[n(m-1)] - -The above matrix also represents the sequential or progressive read-out mode of -the (n, m) Bayer color filter array used in many CCD/CMOS image sensors. - -One compressed video frame consists of a bitstream that encodes for every R, G, -or B pixel the difference between the value of the pixel itself and some -reference pixel value. Pixels are organised in the Bayer pattern and the Bayer -sub-pixels are tracked individually and alternatingly. For example, in the -first line values for the B and G1 pixels are alternatingly encoded, while in -the second line values for the G2 and R pixels are alternatingly encoded. - -The pixel reference value is calculated as follows: -- the 4 top left pixels are encoded in raw uncompressed 8-bit format; -- the value in the top two rows is the value of the pixel left of the current - pixel; -- the value in the left column is the value of the pixel above the current - pixel; -- for all other pixels, the reference value is the average of the value of the - pixel on the left and the value of the pixel above the current pixel; -- there is one code in the bitstream that specifies the value of a pixel - directly (in 4-bit resolution); -- pixel values need to be clamped inside the range [0..255] for proper - decoding. - -The algorithm purely describes the conversion from compressed Bayer code used -in the SN9C10x chips to uncompressed Bayer. Additional steps are required to -convert this to a color image (i.e. a color interpolation algorithm). - -The following Huffman codes have been found: -0: +0 (relative to reference pixel value) -100: +4 -101: -4? -1110xxxx: set absolute value to xxxx.0000 -1101: +11 -1111: -11 -11001: +20 -110000: -20 -110001: ??? - these codes are apparently not used - -[1] The Huffman compression algorithm has been reverse-engineered and - documented by Bertrik Sikken. - - -12. Contact information -======================= -The author may be contacted by e-mail at . - -GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is -'FCE635A4'; the public 1024-bit key should be available at any keyserver; -the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. - - -13. Credits -=========== -Many thanks to following persons for their contribute (listed in alphabetical -order): - -- Luca Capello for the donation of a webcam; -- Philippe Coval for having helped testing the PAS202BCA image sensor; -- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the - donation of a webcam; -- Jon Hollstrom for the donation of a webcam; -- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB - image sensor; -- Stefano Mozzi, who donated 45 EU; -- Andrew Pearce for the donation of a webcam; -- Bertrik Sikken, who reverse-engineered and documented the Huffman compression - algorithm used in the SN9C10x controllers and implemented the first decoder; -- Mizuno Takafumi for the donation of a webcam; -- an "anonymous" donator (who didn't want his name to be revealed) for the - donation of a webcam. diff --git a/Documentation/usb/stv680.txt b/Documentation/usb/stv680.txt deleted file mode 100644 index 6448041e7a37..000000000000 --- a/Documentation/usb/stv680.txt +++ /dev/null @@ -1,55 +0,0 @@ -Linux driver for STV0680 based USB cameras - -Copyright, 2001, Kevin Sisson - - -INTRODUCTION: - -STMicroelectronics produces the STV0680B chip, which comes in two -types, -001 and -003. The -003 version allows the recording and downloading -of sound clips from the camera, and allows a flash attachment. Otherwise, -it uses the same commands as the -001 version. Both versions support a -variety of SDRAM sizes and sensors, allowing for a maximum of 26 VGA or 20 -CIF pictures. The STV0680 supports either a serial or a usb interface, and -video is possible through the usb interface. - -The following cameras are known to work with this driver, although any -camera with Vendor/Product codes of 0553/0202 should work: - -Aiptek Pencam (various models) -Nisis QuickPix 2 -Radio Shack 'Kid's digital camera' (#60-1207) -At least one Trust Spycam model -Several other European brand models - -WHAT YOU NEED: - -- USB support -- VIDEO4LINUX support - -More information about USB support for linux can be found at: -http://www.linux-usb.org - - -MODULE OPTIONS: - -When the driver is compiled as a module, you can set a "swapRGB=1" -option, if necessary, for those applications that require it -(such as xawtv). However, the driver should detect and set this -automatically, so this option should not normally be used. - - -KNOWN PROBLEMS: - -The driver seems to work better with the usb-ohci than the usb-uhci host -controller driver. - -HELP: - -The latest info on this driver can be found at: -http://personal.clt.bellsouth.net/~kjsisson or at -http://stv0680-usb.sourceforge.net - -Any questions to me can be send to: kjsisson@bellsouth.net - - diff --git a/Documentation/usb/w9968cf.txt b/Documentation/usb/w9968cf.txt deleted file mode 100644 index 9d46cd0b19e3..000000000000 --- a/Documentation/usb/w9968cf.txt +++ /dev/null @@ -1,461 +0,0 @@ - - W996[87]CF JPEG USB Dual Mode Camera Chip - Driver for Linux 2.6 (basic version) - ========================================= - - - Documentation - - - -Index -===== -1. Copyright -2. Disclaimer -3. License -4. Overview -5. Supported devices -6. Module dependencies -7. Module loading -8. Module paramaters -9. Contact information -10. Credits - - -1. Copyright -============ -Copyright (C) 2002-2004 by Luca Risolia - - -2. Disclaimer -============= -Winbond is a trademark of Winbond Electronics Corporation. -This software is not sponsored or developed by Winbond. - - -3. License -========== -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program; if not, write to the Free Software -Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - -4. Overview -=========== -This driver supports the video streaming capabilities of the devices mounting -Winbond W9967CF and Winbond W9968CF JPEG USB Dual Mode Camera Chips. OV681 -based cameras should be supported as well. - -The driver is divided into two modules: the basic one, "w9968cf", is needed for -the supported devices to work; the second one, "w9968cf-vpp", is an optional -module, which provides some useful video post-processing functions like video -decoding, up-scaling and colour conversions. - -Note that the official kernels do neither include nor support the second -module for performance purposes. Therefore, it is always recommended to -download and install the latest and complete release of the driver, -replacing the existing one, if present. - -The latest and full-featured version of the W996[87]CF driver can be found at: -http://www.linux-projects.org. Please refer to the documentation included in -that package, if you are going to use it. - -Up to 32 cameras can be handled at the same time. They can be connected and -disconnected from the host many times without turning off the computer, if -your system supports the hotplug facility. - -To change the default settings for each camera, many parameters can be passed -through command line when the module is loaded into memory. - -The driver relies on the Video4Linux, USB and I2C core modules. It has been -designed to run properly on SMP systems as well. An additional module, -"ovcamchip", is mandatory; it provides support for some OmniVision image -sensors connected to the W996[87]CF chips; if found in the system, the module -will be automatically loaded by default (provided that the kernel has been -compiled with the automatic module loading option). - - -5. Supported devices -==================== -At the moment, known W996[87]CF and OV681 based devices are: -- Aroma Digi Pen VGA Dual Mode ADG-5000 (unknown image sensor) -- AVerMedia AVerTV USB (SAA7111A, Philips FI1216Mk2 tuner, PT2313L audio chip) -- Creative Labs Video Blaster WebCam Go (OmniVision OV7610 sensor) -- Creative Labs Video Blaster WebCam Go Plus (OmniVision OV7620 sensor) -- Lebon LDC-035A (unknown image sensor) -- Ezonics EZ-802 EZMega Cam (OmniVision OV8610C sensor) -- OmniVision OV8610-EDE (OmniVision OV8610 sensor) -- OPCOM Digi Pen VGA Dual Mode Pen Camera (unknown image sensor) -- Pretec Digi Pen-II (OmniVision OV7620 sensor) -- Pretec DigiPen-480 (OmniVision OV8610 sensor) - -If you know any other W996[87]CF or OV681 based cameras, please contact me. - -The list above does not imply that all those devices work with this driver: up -until now only webcams that have an image sensor supported by the "ovcamchip" -module work. Kernel messages will always tell you whether this is case. - -Possible external microcontrollers of those webcams are not supported: this -means that still images cannot be downloaded from the device memory. - -Furthermore, it's worth to note that I was only able to run tests on my -"Creative Labs Video Blaster WebCam Go". Donations of other models, for -additional testing and full support, would be much appreciated. - - -6. Module dependencies -====================== -For it to work properly, the driver needs kernel support for Video4Linux, USB -and I2C, and the "ovcamchip" module for the image sensor. Make sure you are not -actually using any external "ovcamchip" module, given that the W996[87]CF -driver depends on the version of the module present in the official kernels. - -The following options of the kernel configuration file must be enabled and -corresponding modules must be compiled: - - # Multimedia devices - # - CONFIG_VIDEO_DEV=m - - # I2C support - # - CONFIG_I2C=m - -The I2C core module can be compiled statically in the kernel as well. - - # OmniVision Camera Chip support - # - CONFIG_VIDEO_OVCAMCHIP=m - - # USB support - # - CONFIG_USB=m - -In addition, depending on the hardware being used, only one of the modules -below is necessary: - - # USB Host Controller Drivers - # - CONFIG_USB_EHCI_HCD=m - CONFIG_USB_UHCI_HCD=m - CONFIG_USB_OHCI_HCD=m - -And finally: - - # USB Multimedia devices - # - CONFIG_USB_W9968CF=m - - -7. Module loading -================= -To use the driver, it is necessary to load the "w9968cf" module into memory -after every other module required. - -Loading can be done this way, from root: - - [root@localhost home]# modprobe usbcore - [root@localhost home]# modprobe i2c-core - [root@localhost home]# modprobe videodev - [root@localhost home]# modprobe w9968cf - -At this point the pertinent devices should be recognized: "dmesg" can be used -to analyze kernel messages: - - [user@localhost home]$ dmesg - -There are a lot of parameters the module can use to change the default -settings for each device. To list every possible parameter with a brief -explanation about them and which syntax to use, it is recommended to run the -"modinfo" command: - - [root@locahost home]# modinfo w9968cf - - -8. Module parameters -==================== -Module parameters are listed below: -------------------------------------------------------------------------------- -Name: ovmod_load -Type: bool -Syntax: <0|1> -Description: Automatic 'ovcamchip' module loading: 0 disabled, 1 enabled. - If enabled, 'insmod' searches for the required 'ovcamchip' - module in the system, according to its configuration, and - loads that module automatically. This action is performed as - once soon as the 'w9968cf' module is loaded into memory. -Default: 1 -Note: The kernel must be compiled with the CONFIG_KMOD option - enabled for the 'ovcamchip' module to be loaded and for - this parameter to be present. -------------------------------------------------------------------------------- -Name: simcams -Type: int -Syntax: -Description: Number of cameras allowed to stream simultaneously. - n may vary from 0 to 32. -Default: 32 -------------------------------------------------------------------------------- -Name: video_nr -Type: int array (min = 0, max = 32) -Syntax: <-1|n[,...]> -Description: Specify V4L minor mode number. - -1 = use next available - n = use minor number n - You can specify up to 32 cameras this way. - For example: - video_nr=-1,2,-1 would assign minor number 2 to the second - recognized camera and use auto for the first one and for every - other camera. -Default: -1 -------------------------------------------------------------------------------- -Name: packet_size -Type: int array (min = 0, max = 32) -Syntax: -Description: Specify the maximum data payload size in bytes for alternate - settings, for each device. n is scaled between 63 and 1023. -Default: 1023 -------------------------------------------------------------------------------- -Name: max_buffers -Type: int array (min = 0, max = 32) -Syntax: -Description: For advanced users. - Specify the maximum number of video frame buffers to allocate - for each device, from 2 to 32. -Default: 2 -------------------------------------------------------------------------------- -Name: double_buffer -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Hardware double buffering: 0 disabled, 1 enabled. - It should be enabled if you want smooth video output: if you - obtain out of sync. video, disable it, or try to - decrease the 'clockdiv' module parameter value. -Default: 1 for every device. -------------------------------------------------------------------------------- -Name: clamping -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Video data clamping: 0 disabled, 1 enabled. -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: filter_type -Type: int array (min = 0, max = 32) -Syntax: <0|1|2[,...]> -Description: Video filter type. - 0 none, 1 (1-2-1) 3-tap filter, 2 (2-3-6-3-2) 5-tap filter. - The filter is used to reduce noise and aliasing artifacts - produced by the CCD or CMOS image sensor. -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: largeview -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Large view: 0 disabled, 1 enabled. -Default: 1 for every device. -------------------------------------------------------------------------------- -Name: upscaling -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Software scaling (for non-compressed video only): - 0 disabled, 1 enabled. - Disable it if you have a slow CPU or you don't have enough - memory. -Default: 0 for every device. -Note: If 'w9968cf-vpp' is not present, this parameter is set to 0. -------------------------------------------------------------------------------- -Name: decompression -Type: int array (min = 0, max = 32) -Syntax: <0|1|2[,...]> -Description: Software video decompression: - 0 = disables decompression - (doesn't allow formats needing decompression). - 1 = forces decompression - (allows formats needing decompression only). - 2 = allows any permitted formats. - Formats supporting (de)compressed video are YUV422P and - YUV420P/YUV420 in any resolutions where width and height are - multiples of 16. -Default: 2 for every device. -Note: If 'w9968cf-vpp' is not present, forcing decompression is not - allowed; in this case this parameter is set to 2. -------------------------------------------------------------------------------- -Name: force_palette -Type: int array (min = 0, max = 32) -Syntax: <0|9|10|13|15|8|7|1|6|3|4|5[,...]> -Description: Force picture palette. - In order: - 0 = Off - allows any of the following formats: - 9 = UYVY 16 bpp - Original video, compression disabled - 10 = YUV420 12 bpp - Original video, compression enabled - 13 = YUV422P 16 bpp - Original video, compression enabled - 15 = YUV420P 12 bpp - Original video, compression enabled - 8 = YUVY 16 bpp - Software conversion from UYVY - 7 = YUV422 16 bpp - Software conversion from UYVY - 1 = GREY 8 bpp - Software conversion from UYVY - 6 = RGB555 16 bpp - Software conversion from UYVY - 3 = RGB565 16 bpp - Software conversion from UYVY - 4 = RGB24 24 bpp - Software conversion from UYVY - 5 = RGB32 32 bpp - Software conversion from UYVY - When not 0, this parameter will override 'decompression'. -Default: 0 for every device. Initial palette is 9 (UYVY). -Note: If 'w9968cf-vpp' is not present, this parameter is set to 9. -------------------------------------------------------------------------------- -Name: force_rgb -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Read RGB video data instead of BGR: - 1 = use RGB component ordering. - 0 = use BGR component ordering. - This parameter has effect when using RGBX palettes only. -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: autobright -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Image sensor automatically changes brightness: - 0 = no, 1 = yes -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: autoexp -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Image sensor automatically changes exposure: - 0 = no, 1 = yes -Default: 1 for every device. -------------------------------------------------------------------------------- -Name: lightfreq -Type: int array (min = 0, max = 32) -Syntax: <50|60[,...]> -Description: Light frequency in Hz: - 50 for European and Asian lighting, 60 for American lighting. -Default: 50 for every device. -------------------------------------------------------------------------------- -Name: bandingfilter -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Banding filter to reduce effects of fluorescent - lighting: - 0 disabled, 1 enabled. - This filter tries to reduce the pattern of horizontal - light/dark bands caused by some (usually fluorescent) lighting. -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: clockdiv -Type: int array (min = 0, max = 32) -Syntax: <-1|n[,...]> -Description: Force pixel clock divisor to a specific value (for experts): - n may vary from 0 to 127. - -1 for automatic value. - See also the 'double_buffer' module parameter. -Default: -1 for every device. -------------------------------------------------------------------------------- -Name: backlight -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Objects are lit from behind: - 0 = no, 1 = yes -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: mirror -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: Reverse image horizontally: - 0 = no, 1 = yes -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: monochrome -Type: bool array (min = 0, max = 32) -Syntax: <0|1[,...]> -Description: The image sensor is monochrome: - 0 = no, 1 = yes -Default: 0 for every device. -------------------------------------------------------------------------------- -Name: brightness -Type: long array (min = 0, max = 32) -Syntax: -Description: Set picture brightness (0-65535). - This parameter has no effect if 'autobright' is enabled. -Default: 31000 for every device. -------------------------------------------------------------------------------- -Name: hue -Type: long array (min = 0, max = 32) -Syntax: -Description: Set picture hue (0-65535). -Default: 32768 for every device. -------------------------------------------------------------------------------- -Name: colour -Type: long array (min = 0, max = 32) -Syntax: -Description: Set picture saturation (0-65535). -Default: 32768 for every device. -------------------------------------------------------------------------------- -Name: contrast -Type: long array (min = 0, max = 32) -Syntax: -Description: Set picture contrast (0-65535). -Default: 50000 for every device. -------------------------------------------------------------------------------- -Name: whiteness -Type: long array (min = 0, max = 32) -Syntax: -Description: Set picture whiteness (0-65535). -Default: 32768 for every device. -------------------------------------------------------------------------------- -Name: debug -Type: int -Syntax: -Description: Debugging information level, from 0 to 6: - 0 = none (use carefully) - 1 = critical errors - 2 = significant informations - 3 = configuration or general messages - 4 = warnings - 5 = called functions - 6 = function internals - Level 5 and 6 are useful for testing only, when only one - device is used. -Default: 2 -------------------------------------------------------------------------------- -Name: specific_debug -Type: bool -Syntax: <0|1> -Description: Enable or disable specific debugging messages: - 0 = print messages concerning every level <= 'debug' level. - 1 = print messages concerning the level indicated by 'debug'. -Default: 0 -------------------------------------------------------------------------------- - - -9. Contact information -====================== -I may be contacted by e-mail at . - -I can accept GPG/PGP encrypted e-mail. My GPG key ID is 'FCE635A4'. -My public 1024-bit key should be available at your keyserver; the fingerprint -is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. - - -10. Credits -========== -The development would not have proceed much further without having looked at -the source code of other drivers and without the help of several persons; in -particular: - -- the I2C interface to kernel and high-level image sensor control routines have - been taken from the OV511 driver by Mark McClelland; - -- memory management code has been copied from the bttv driver by Ralph Metzler, - Marcus Metzler and Gerd Knorr; - -- the low-level I2C read function has been written by Frederic Jouault; - -- the low-level I2C fast write function has been written by Piotr Czerczak. diff --git a/Documentation/usb/zc0301.txt b/Documentation/usb/zc0301.txt deleted file mode 100644 index f55262c6733b..000000000000 --- a/Documentation/usb/zc0301.txt +++ /dev/null @@ -1,254 +0,0 @@ - - ZC0301 Image Processor and Control Chip - Driver for Linux - ======================================= - - - Documentation - - - -Index -===== -1. Copyright -2. Disclaimer -3. License -4. Overview and features -5. Module dependencies -6. Module loading -7. Module parameters -8. Supported devices -9. Notes for V4L2 application developers -10. Contact information -11. Credits - - -1. Copyright -============ -Copyright (C) 2006 by Luca Risolia - - -2. Disclaimer -============= -This software is not developed or sponsored by Z-Star Microelectronics Corp. -Trademarks are property of their respective owner. - - -3. License -========== -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2 of the License, or -(at your option) any later version. - -This program is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with this program; if not, write to the Free Software -Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - -4. Overview and features -======================== -This driver supports the video interface of the devices mounting the ZC0301 -Image Processor and Control Chip. - -The driver relies on the Video4Linux2 and USB core modules. It has been -designed to run properly on SMP systems as well. - -The latest version of the ZC0301 driver can be found at the following URL: -http://www.linux-projects.org/ - -Some of the features of the driver are: - -- full compliance with the Video4Linux2 API (see also "Notes for V4L2 - application developers" paragraph); -- available mmap or read/poll methods for video streaming through isochronous - data transfers; -- automatic detection of image sensor; -- video format is standard JPEG; -- dynamic driver control thanks to various module parameters (see "Module - parameters" paragraph); -- up to 64 cameras can be handled at the same time; they can be connected and - disconnected from the host many times without turning off the computer, if - the system supports hotplugging; - - -5. Module dependencies -====================== -For it to work properly, the driver needs kernel support for Video4Linux and -USB. - -The following options of the kernel configuration file must be enabled and -corresponding modules must be compiled: - - # Multimedia devices - # - CONFIG_VIDEO_DEV=m - - # USB support - # - CONFIG_USB=m - -In addition, depending on the hardware being used, the modules below are -necessary: - - # USB Host Controller Drivers - # - CONFIG_USB_EHCI_HCD=m - CONFIG_USB_UHCI_HCD=m - CONFIG_USB_OHCI_HCD=m - -The ZC0301 controller also provides a built-in microphone interface. It is -supported by the USB Audio driver thanks to the ALSA API: - - # Sound - # - CONFIG_SOUND=y - - # Advanced Linux Sound Architecture - # - CONFIG_SND=m - - # USB devices - # - CONFIG_SND_USB_AUDIO=m - -And finally: - - # USB Multimedia devices - # - CONFIG_USB_ZC0301=m - - -6. Module loading -================= -To use the driver, it is necessary to load the "zc0301" module into memory -after every other module required: "videodev", "usbcore" and, depending on -the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". - -Loading can be done as shown below: - - [root@localhost home]# modprobe zc0301 - -At this point the devices should be recognized. You can invoke "dmesg" to -analyze kernel messages and verify that the loading process has gone well: - - [user@localhost home]$ dmesg - - -7. Module parameters -==================== -Module parameters are listed below: -------------------------------------------------------------------------------- -Name: video_nr -Type: short array (min = 0, max = 64) -Syntax: <-1|n[,...]> -Description: Specify V4L2 minor mode number: - -1 = use next available - n = use minor number n - You can specify up to 64 cameras this way. - For example: - video_nr=-1,2,-1 would assign minor number 2 to the second - registered camera and use auto for the first one and for every - other camera. -Default: -1 -------------------------------------------------------------------------------- -Name: force_munmap -Type: bool array (min = 0, max = 64) -Syntax: <0|1[,...]> -Description: Force the application to unmap previously mapped buffer memory - before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not - all the applications support this feature. This parameter is - specific for each detected camera. - 0 = do not force memory unmapping - 1 = force memory unmapping (save memory) -Default: 0 -------------------------------------------------------------------------------- -Name: frame_timeout -Type: uint array (min = 0, max = 64) -Syntax: -Description: Timeout for a video frame in seconds. This parameter is - specific for each detected camera. This parameter can be - changed at runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- -Name: debug -Type: ushort -Syntax: -Description: Debugging information level, from 0 to 3: - 0 = none (use carefully) - 1 = critical errors - 2 = significant informations - 3 = more verbose messages - Level 3 is useful for testing only, when only one device - is used at the same time. It also shows some more informations - about the hardware being detected. This module parameter can be - changed at runtime thanks to the /sys filesystem interface. -Default: 2 -------------------------------------------------------------------------------- - - -8. Supported devices -==================== -None of the names of the companies as well as their products will be mentioned -here. They have never collaborated with the author, so no advertising. - -From the point of view of a driver, what unambiguously identify a device are -its vendor and product USB identifiers. Below is a list of known identifiers of -devices mounting the ZC0301 Image Processor and Control Chips: - -Vendor ID Product ID ---------- ---------- -0x041e 0x4017 -0x041e 0x401c -0x041e 0x401e -0x041e 0x4034 -0x041e 0x4035 -0x046d 0x08ae -0x0ac8 0x0301 -0x10fd 0x8050 - -The list above does not imply that all those devices work with this driver: up -until now only the ones that mount the following image sensors are supported; -kernel messages will always tell you whether this is the case: - -Model Manufacturer ------ ------------ -PAS202BCB PixArt Imaging, Inc. - - -9. Notes for V4L2 application developers -======================================== -This driver follows the V4L2 API specifications. In particular, it enforces two -rules: - -- exactly one I/O method, either "mmap" or "read", is associated with each -file descriptor. Once it is selected, the application must close and reopen the -device to switch to the other I/O method; - -- although it is not mandatory, previously mapped buffer memory should always -be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. -The same number of buffers as before will be allocated again to match the size -of the new video frames, so you have to map the buffers again before any I/O -attempts on them. - - -10. Contact information -======================= -The author may be contacted by e-mail at . - -GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is -'FCE635A4'; the public 1024-bit key should be available at any keyserver; -the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. - - -11. Credits -=========== -- Informations about the chip internals needed to enable the I2C protocol have - been taken from the documentation of the ZC030x Video4Linux1 driver written - by Andrew Birkett ; -- The initialization values of the ZC0301 controller connected to the PAS202BCB - image sensor have been taken from the SPCA5XX driver maintained by - Michel Xhaard . diff --git a/Documentation/video4linux/et61x251.txt b/Documentation/video4linux/et61x251.txt new file mode 100644 index 000000000000..29340282ab5f --- /dev/null +++ b/Documentation/video4linux/et61x251.txt @@ -0,0 +1,314 @@ + + ET61X[12]51 PC Camera Controllers + Driver for Linux + ================================= + + - Documentation - + + +Index +===== +1. Copyright +2. Disclaimer +3. License +4. Overview and features +5. Module dependencies +6. Module loading +7. Module parameters +8. Optional device control through "sysfs" +9. Supported devices +10. Notes for V4L2 application developers +11. Contact information + + +1. Copyright +============ +Copyright (C) 2006 by Luca Risolia + + +2. Disclaimer +============= +Etoms is a trademark of Etoms Electronics Corp. +This software is not developed or sponsored by Etoms Electronics. + + +3. License +========== +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + +4. Overview and features +======================== +This driver supports the video interface of the devices mounting the ET61X151 +or ET61X251 PC Camera Controllers. + +It's worth to note that Etoms Electronics has never collaborated with the +author during the development of this project; despite several requests, +Etoms Electronics also refused to release enough detailed specifications of +the video compression engine. + +The driver relies on the Video4Linux2 and USB core modules. It has been +designed to run properly on SMP systems as well. + +The latest version of the ET61X[12]51 driver can be found at the following URL: +http://www.linux-projects.org/ + +Some of the features of the driver are: + +- full compliance with the Video4Linux2 API (see also "Notes for V4L2 + application developers" paragraph); +- available mmap or read/poll methods for video streaming through isochronous + data transfers; +- automatic detection of image sensor; +- support for any window resolutions and optional panning within the maximum + pixel area of image sensor; +- image downscaling with arbitrary scaling factors from 1 and 2 in both + directions (see "Notes for V4L2 application developers" paragraph); +- two different video formats for uncompressed or compressed data in low or + high compression quality (see also "Notes for V4L2 application developers" + paragraph); +- full support for the capabilities of every possible image sensors that can + be connected to the ET61X[12]51 bridges, including, for istance, red, green, + blue and global gain adjustments and exposure control (see "Supported + devices" paragraph for details); +- use of default color settings for sunlight conditions; +- dynamic I/O interface for both ET61X[12]51 and image sensor control (see + "Optional device control through 'sysfs'" paragraph); +- dynamic driver control thanks to various module parameters (see "Module + parameters" paragraph); +- up to 64 cameras can be handled at the same time; they can be connected and + disconnected from the host many times without turning off the computer, if + the system supports hotplugging; +- no known bugs. + + +5. Module dependencies +====================== +For it to work properly, the driver needs kernel support for Video4Linux and +USB. + +The following options of the kernel configuration file must be enabled and +corresponding modules must be compiled: + + # Multimedia devices + # + CONFIG_VIDEO_DEV=m + +To enable advanced debugging functionality on the device through /sysfs: + + # Multimedia devices + # + CONFIG_VIDEO_ADV_DEBUG=y + + # USB support + # + CONFIG_USB=m + +In addition, depending on the hardware being used, the modules below are +necessary: + + # USB Host Controller Drivers + # + CONFIG_USB_EHCI_HCD=m + CONFIG_USB_UHCI_HCD=m + CONFIG_USB_OHCI_HCD=m + +And finally: + + # USB Multimedia devices + # + CONFIG_USB_ET61X251=m + + +6. Module loading +================= +To use the driver, it is necessary to load the "et61x251" module into memory +after every other module required: "videodev", "usbcore" and, depending on +the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". + +Loading can be done as shown below: + + [root@localhost home]# modprobe et61x251 + +At this point the devices should be recognized. You can invoke "dmesg" to +analyze kernel messages and verify that the loading process has gone well: + + [user@localhost home]$ dmesg + + +7. Module parameters +==================== +Module parameters are listed below: +------------------------------------------------------------------------------- +Name: video_nr +Type: short array (min = 0, max = 64) +Syntax: <-1|n[,...]> +Description: Specify V4L2 minor mode number: + -1 = use next available + n = use minor number n + You can specify up to 64 cameras this way. + For example: + video_nr=-1,2,-1 would assign minor number 2 to the second + registered camera and use auto for the first one and for every + other camera. +Default: -1 +------------------------------------------------------------------------------- +Name: force_munmap +Type: bool array (min = 0, max = 64) +Syntax: <0|1[,...]> +Description: Force the application to unmap previously mapped buffer memory + before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not + all the applications support this feature. This parameter is + specific for each detected camera. + 0 = do not force memory unmapping + 1 = force memory unmapping (save memory) +Default: 0 +------------------------------------------------------------------------------- +Name: frame_timeout +Type: uint array (min = 0, max = 64) +Syntax: +Description: Timeout for a video frame in seconds. This parameter is + specific for each detected camera. This parameter can be + changed at runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- +Name: debug +Type: ushort +Syntax: +Description: Debugging information level, from 0 to 3: + 0 = none (use carefully) + 1 = critical errors + 2 = significant informations + 3 = more verbose messages + Level 3 is useful for testing only, when only one device + is used at the same time. It also shows some more informations + about the hardware being detected. This module parameter can be + changed at runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- + + +8. Optional device control through "sysfs" +========================================== +If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, +it is possible to read and write both the ET61X[12]51 and the image sensor +registers by using the "sysfs" filesystem interface. + +There are four files in the /sys/class/video4linux/videoX directory for each +registered camera: "reg", "val", "i2c_reg" and "i2c_val". The first two files +control the ET61X[12]51 bridge, while the other two control the sensor chip. +"reg" and "i2c_reg" hold the values of the current register index where the +following reading/writing operations are addressed at through "val" and +"i2c_val". Their use is not intended for end-users, unless you know what you +are doing. Remember that you must be logged in as root before writing to them. + +As an example, suppose we were to want to read the value contained in the +register number 1 of the sensor register table - which is usually the product +identifier - of the camera registered as "/dev/video0": + + [root@localhost #] cd /sys/class/video4linux/video0 + [root@localhost #] echo 1 > i2c_reg + [root@localhost #] cat i2c_val + +Note that if the sensor registers can not be read, "cat" will fail. +To avoid race conditions, all the I/O accesses to the files are serialized. + + +9. Supported devices +==================== +None of the names of the companies as well as their products will be mentioned +here. They have never collaborated with the author, so no advertising. + +From the point of view of a driver, what unambiguously identify a device are +its vendor and product USB identifiers. Below is a list of known identifiers of +devices mounting the ET61X[12]51 PC camera controllers: + +Vendor ID Product ID +--------- ---------- +0x102c 0x6151 +0x102c 0x6251 +0x102c 0x6253 +0x102c 0x6254 +0x102c 0x6255 +0x102c 0x6256 +0x102c 0x6257 +0x102c 0x6258 +0x102c 0x6259 +0x102c 0x625a +0x102c 0x625b +0x102c 0x625c +0x102c 0x625d +0x102c 0x625e +0x102c 0x625f +0x102c 0x6260 +0x102c 0x6261 +0x102c 0x6262 +0x102c 0x6263 +0x102c 0x6264 +0x102c 0x6265 +0x102c 0x6266 +0x102c 0x6267 +0x102c 0x6268 +0x102c 0x6269 + +The following image sensors are supported: + +Model Manufacturer +----- ------------ +TAS5130D1B Taiwan Advanced Sensor Corporation + +All the available control settings of each image sensor are supported through +the V4L2 interface. + + +10. Notes for V4L2 application developers +========================================= +This driver follows the V4L2 API specifications. In particular, it enforces two +rules: + +- exactly one I/O method, either "mmap" or "read", is associated with each +file descriptor. Once it is selected, the application must close and reopen the +device to switch to the other I/O method; + +- although it is not mandatory, previously mapped buffer memory should always +be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. +The same number of buffers as before will be allocated again to match the size +of the new video frames, so you have to map the buffers again before any I/O +attempts on them. + +Consistently with the hardware limits, this driver also supports image +downscaling with arbitrary scaling factors from 1 and 2 in both directions. +However, the V4L2 API specifications don't correctly define how the scaling +factor can be chosen arbitrarily by the "negotiation" of the "source" and +"target" rectangles. To work around this flaw, we have added the convention +that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the +scaling factor is restored to 1. + +This driver supports two different video formats: the first one is the "8-bit +Sequential Bayer" format and can be used to obtain uncompressed video data +from the device through the current I/O method, while the second one provides +"raw" compressed video data (without frame headers not related to the +compressed data). The current compression quality may vary from 0 to 1 and can +be selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP +V4L2 ioctl's. + + +11. Contact information +======================= +The author may be contacted by e-mail at . + +GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is +'FCE635A4'; the public 1024-bit key should be available at any keyserver; +the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. diff --git a/Documentation/video4linux/ibmcam.txt b/Documentation/video4linux/ibmcam.txt new file mode 100644 index 000000000000..4a40a2e99451 --- /dev/null +++ b/Documentation/video4linux/ibmcam.txt @@ -0,0 +1,324 @@ +README for Linux device driver for the IBM "C-It" USB video camera + +INTRODUCTION: + +This driver does not use all features known to exist in +the IBM camera. However most of needed features work well. + +This driver was developed using logs of observed USB traffic +which was produced by standard Windows driver (c-it98.sys). +I did not have data sheets from Xirlink. + +Video formats: + 128x96 [model 1] + 176x144 + 320x240 [model 2] + 352x240 [model 2] + 352x288 +Frame rate: 3 - 30 frames per second (FPS) +External interface: USB +Internal interface: Video For Linux (V4L) +Supported controls: +- by V4L: Contrast, Brightness, Color, Hue +- by driver options: frame rate, lighting conditions, video format, + default picture settings, sharpness. + +SUPPORTED CAMERAS: + +Xirlink "C-It" camera, also known as "IBM PC Camera". +The device uses proprietary ASIC (and compression method); +it is manufactured by Xirlink. See http://www.xirlink.com/ +(renamed to http://www.veo.com), http://www.ibmpccamera.com, +or http://www.c-itnow.com/ for details and pictures. + +This very chipset ("X Chip", as marked at the factory) +is used in several other cameras, and they are supported +as well: + +- IBM NetCamera +- Veo Stingray + +The Linux driver was developed with camera with following +model number (or FCC ID): KSX-XVP510. This camera has three +interfaces, each with one endpoint (control, iso, iso). This +type of cameras is referred to as "model 1". These cameras are +no longer manufactured. + +Xirlink now manufactures new cameras which are somewhat different. +In particular, following models [FCC ID] belong to that category: + +XVP300 [KSX-X9903] +XVP600 [KSX-X9902] +XVP610 [KSX-X9902] + +(see http://www.xirlink.com/ibmpccamera/ for updates, they refer +to these new cameras by Windows driver dated 12-27-99, v3005 BETA) +These cameras have two interfaces, one endpoint in each (iso, bulk). +Such type of cameras is referred to as "model 2". They are supported +(with exception of 352x288 native mode). + +Some IBM NetCameras (Model 4) are made to generate only compressed +video streams. This is great for performance, but unfortunately +nobody knows how to decompress the stream :-( Therefore, these +cameras are *unsupported* and if you try to use one of those, all +you get is random colored horizontal streaks, not the image! +If you have one of those cameras, you probably should return it +to the store and get something that is supported. + +Tell me more about all that "model" business +-------------------------------------------- + +I just invented model numbers to uniquely identify flavors of the +hardware/firmware that were sold. It was very confusing to use +brand names or some other internal numbering schemes. So I found +by experimentation that all Xirlink chipsets fall into four big +classes, and I called them "models". Each model is programmed in +its own way, and each model sends back the video in its own way. + +Quirks of Model 2 cameras: +------------------------- + +Model 2 does not have hardware contrast control. Corresponding V4L +control is implemented in software, which is not very nice to your +CPU, but at least it works. + +This driver provides 352x288 mode by switching the camera into +quasi-352x288 RGB mode (800 Kbits per frame) essentially limiting +this mode to 10 frames per second or less, in ideal conditions on +the bus (USB is shared, after all). The frame rate +has to be programmed very conservatively. Additional concern is that +frame rate depends on brightness setting; therefore the picture can +be good at one brightness and broken at another! I did not want to fix +the frame rate at slowest setting, but I had to move it pretty much down +the scale (so that framerate option barely matters). I also noticed that +camera after first powering up produces frames slightly faster than during +consecutive uses. All this means that if you use 352x288 (which is +default), be warned - you may encounter broken picture on first connect; +try to adjust brightness - brighter image is slower, so USB will be able +to send all data. However if you regularly use Model 2 cameras you may +prefer 176x144 which makes perfectly good I420, with no scaling and +lesser demands on USB (300 Kbits per second, or 26 frames per second). + +Another strange effect of 352x288 mode is the fine vertical grid visible +on some colored surfaces. I am sure it is caused by me not understanding +what the camera is trying to say. Blame trade secrets for that. + +The camera that I had also has a hardware quirk: if disconnected, +it needs few minutes to "relax" before it can be plugged in again +(poorly designed USB processor reset circuit?) + +[Veo Stingray with Product ID 0x800C is also Model 2, but I haven't +observed this particular flaw in it.] + +Model 2 camera can be programmed for very high sensitivity (even starlight +may be enough), this makes it convenient for tinkering with. The driver +code has enough comments to help a programmer to tweak the camera +as s/he feels necessary. + +WHAT YOU NEED: + +- A supported IBM PC (C-it) camera (model 1 or 2) + +- A Linux box with USB support (2.3/2.4; 2.2 w/backport may work) + +- A Video4Linux compatible frame grabber program such as xawtv. + +HOW TO COMPILE THE DRIVER: + +You need to compile the driver only if you are a developer +or if you want to make changes to the code. Most distributions +precompile all modules, so you can go directly to the next +section "HOW TO USE THE DRIVER". + +The ibmcam driver uses usbvideo helper library (module), +so if you are studying the ibmcam code you will be led there. + +The driver itself consists of only one file in usb/ directory: +ibmcam.c. This file is included into the Linux kernel build +process if you configure the kernel for CONFIG_USB_IBMCAM. +Run "make xconfig" and in USB section you will find the IBM +camera driver. Select it, save the configuration and recompile. + +HOW TO USE THE DRIVER: + +I recommend to compile driver as a module. This gives you an +easier access to its configuration. The camera has many more +settings than V4L can operate, so some settings are done using +module options. + +To begin with, on most modern Linux distributions the driver +will be automatically loaded whenever you plug the supported +camera in. Therefore, you don't need to do anything. However +if you want to experiment with some module parameters then +you can load and unload the driver manually, with camera +plugged in or unplugged. + +Typically module is installed with command 'modprobe', like this: + +# modprobe ibmcam framerate=1 + +Alternatively you can use 'insmod' in similar fashion: + +# insmod /lib/modules/2.x.y/usb/ibmcam.o framerate=1 + +Module can be inserted with camera connected or disconnected. + +The driver can have options, though some defaults are provided. + +Driver options: (* indicates that option is model-dependent) + +Name Type Range [default] Example +-------------- -------------- -------------- ------------------ +debug Integer 0-9 [0] debug=1 +flags Integer 0-0xFF [0] flags=0x0d +framerate Integer 0-6 [2] framerate=1 +hue_correction Integer 0-255 [128] hue_correction=115 +init_brightness Integer 0-255 [128] init_brightness=100 +init_contrast Integer 0-255 [192] init_contrast=200 +init_color Integer 0-255 [128] init_color=130 +init_hue Integer 0-255 [128] init_hue=115 +lighting Integer 0-2* [1] lighting=2 +sharpness Integer 0-6* [4] sharpness=3 +size Integer 0-2* [2] size=1 + +Options for Model 2 only: + +Name Type Range [default] Example +-------------- -------------- -------------- ------------------ +init_model2_rg Integer 0..255 [0x70] init_model2_rg=128 +init_model2_rg2 Integer 0..255 [0x2f] init_model2_rg2=50 +init_model2_sat Integer 0..255 [0x34] init_model2_sat=65 +init_model2_yb Integer 0..255 [0xa0] init_model2_yb=200 + +debug You don't need this option unless you are a developer. + If you are a developer then you will see in the code + what values do what. 0=off. + +flags This is a bit mask, and you can combine any number of + bits to produce what you want. Usually you don't want + any of extra features this option provides: + + FLAGS_RETRY_VIDIOCSYNC 1 This bit allows to retry failed + VIDIOCSYNC ioctls without failing. + Will work with xawtv, will not + with xrealproducer. Default is + not set. + FLAGS_MONOCHROME 2 Activates monochrome (b/w) mode. + FLAGS_DISPLAY_HINTS 4 Shows colored pixels which have + magic meaning to developers. + FLAGS_OVERLAY_STATS 8 Shows tiny numbers on screen, + useful only for debugging. + FLAGS_FORCE_TESTPATTERN 16 Shows blue screen with numbers. + FLAGS_SEPARATE_FRAMES 32 Shows each frame separately, as + it was received from the camera. + Default (not set) is to mix the + preceding frame in to compensate + for occasional loss of Isoc data + on high frame rates. + FLAGS_CLEAN_FRAMES 64 Forces "cleanup" of each frame + prior to use; relevant only if + FLAGS_SEPARATE_FRAMES is set. + Default is not to clean frames, + this is a little faster but may + produce flicker if frame rate is + too high and Isoc data gets lost. + FLAGS_NO_DECODING 128 This flag turns the video stream + decoder off, and dumps the raw + Isoc data from the camera into + the reading process. Useful to + developers, but not to users. + +framerate This setting controls frame rate of the camera. This is + an approximate setting (in terms of "worst" ... "best") + because camera changes frame rate depending on amount + of light available. Setting 0 is slowest, 6 is fastest. + Beware - fast settings are very demanding and may not + work well with all video sizes. Be conservative. + +hue_correction This highly optional setting allows to adjust the + hue of the image in a way slightly different from + what usual "hue" control does. Both controls affect + YUV colorspace: regular "hue" control adjusts only + U component, and this "hue_correction" option similarly + adjusts only V component. However usually it is enough + to tweak only U or V to compensate for colored light or + color temperature; this option simply allows more + complicated correction when and if it is necessary. + +init_brightness These settings specify _initial_ values which will be +init_contrast used to set up the camera. If your V4L application has +init_color its own controls to adjust the picture then these +init_hue controls will be used too. These options allow you to + preconfigure the camera when it gets connected, before + any V4L application connects to it. Good for webcams. + +init_model2_rg These initial settings alter color balance of the +init_model2_rg2 camera on hardware level. All four settings may be used +init_model2_sat to tune the camera to specific lighting conditions. These +init_model2_yb settings only apply to Model 2 cameras. + +lighting This option selects one of three hardware-defined + photosensitivity settings of the camera. 0=bright light, + 1=Medium (default), 2=Low light. This setting affects + frame rate: the dimmer the lighting the lower the frame + rate (because longer exposition time is needed). The + Model 2 cameras allow values more than 2 for this option, + thus enabling extremely high sensitivity at cost of frame + rate, color saturation and imaging sensor noise. + +sharpness This option controls smoothing (noise reduction) + made by camera. Setting 0 is most smooth, setting 6 + is most sharp. Be aware that CMOS sensor used in the + camera is pretty noisy, so if you choose 6 you will + be greeted with "snowy" image. Default is 4. Model 2 + cameras do not support this feature. + +size This setting chooses one of several image sizes that are + supported by this driver. Cameras may support more, but + it's difficult to reverse-engineer all formats. + Following video sizes are supported: + + size=0 128x96 (Model 1 only) + size=1 160x120 + size=2 176x144 + size=3 320x240 (Model 2 only) + size=4 352x240 (Model 2 only) + size=5 352x288 + size=6 640x480 (Model 3 only) + + The 352x288 is the native size of the Model 1 sensor + array, so it's the best resolution the camera can + yield. The best resolution of Model 2 is 176x144, and + larger images are produced by stretching the bitmap. + Model 3 has sensor with 640x480 grid, and it works too, + but the frame rate will be exceptionally low (1-2 FPS); + it may be still OK for some applications, like security. + Choose the image size you need. The smaller image can + support faster frame rate. Default is 352x288. + +For more information and the Troubleshooting FAQ visit this URL: + + http://www.linux-usb.org/ibmcam/ + +WHAT NEEDS TO BE DONE: + +- The button on the camera is not used. I don't know how to get to it. + I know now how to read button on Model 2, but what to do with it? + +- Camera reports its status back to the driver; however I don't know + what returned data means. If camera fails at some initialization + stage then something should be done, and I don't do that because + I don't even know that some command failed. This is mostly Model 1 + concern because Model 2 uses different commands which do not return + status (and seem to complete successfully every time). + +- Some flavors of Model 4 NetCameras produce only compressed video + streams, and I don't know how to decode them. + +CREDITS: + +The code is based in no small part on the CPiA driver by Johannes Erdfelt, +Randy Dunlap, and others. Big thanks to them for their pioneering work on that +and the USB stack. + +I also thank John Lightsey for his donation of the Veo Stingray camera. diff --git a/Documentation/video4linux/ov511.txt b/Documentation/video4linux/ov511.txt new file mode 100644 index 000000000000..142741e3c578 --- /dev/null +++ b/Documentation/video4linux/ov511.txt @@ -0,0 +1,288 @@ +------------------------------------------------------------------------------- +Readme for Linux device driver for the OmniVision OV511 USB to camera bridge IC +------------------------------------------------------------------------------- + +Author: Mark McClelland +Homepage: http://alpha.dyndns.org/ov511 + +INTRODUCTION: + +This is a driver for the OV511, a USB-only chip used in many "webcam" devices. +Any camera using the OV511/OV511+ and the OV6620/OV7610/20/20AE should work. +Video capture devices that use the Philips SAA7111A decoder also work. It +supports streaming and capture of color or monochrome video via the Video4Linux +API. Most V4L apps are compatible with it. Most resolutions with a width and +height that are a multiple of 8 are supported. + +If you need more information, please visit the OV511 homepage at the above URL. + +WHAT YOU NEED: + +- If you want to help with the development, get the chip's specification docs at + http://www.ovt.com/omniusbp.html + +- A Video4Linux compatible frame grabber program (I recommend vidcat and xawtv) + vidcat is part of the w3cam package: http://mpx.freeshell.net/ + xawtv is available at: http://linux.bytesex.org/xawtv/ + +HOW TO USE IT: + +Note: These are simplified instructions. For complete instructions see: + http://alpha.dyndns.org/ov511/install.html + +You must have first compiled USB support, support for your specific USB host +controller (UHCI or OHCI), and Video4Linux support for your kernel (I recommend +making them modules.) Make sure "Enforce bandwidth allocation" is NOT enabled. + +Next, (as root): + + modprobe usbcore + modprobe usb-uhci modprobe usb-ohci + modprobe videodev + modprobe ov511 + +If it is not already there (it usually is), create the video device: + + mknod /dev/video0 c 81 0 + +Optionally, symlink /dev/video to /dev/video0 + +You will have to set permissions on this device to allow you to read/write +from it: + + chmod 666 /dev/video + chmod 666 /dev/video0 (if necessary) + +Now you are ready to run a video app! Both vidcat and xawtv work well for me +at 640x480. + +[Using vidcat:] + + vidcat -s 640x480 -p c > test.jpg + xview test.jpg + +[Using xawtv:] + +From the main xawtv directory: + + make clean + ./configure + make + make install + +Now you should be able to run xawtv. Right click for the options dialog. + +MODULE PARAMETERS: + + You can set these with: insmod ov511 NAME=VALUE + There is currently no way to set these on a per-camera basis. + + NAME: autobright + TYPE: integer (Boolean) + DEFAULT: 1 + DESC: Brightness is normally under automatic control and can't be set + manually by the video app. Set to 0 for manual control. + + NAME: autogain + TYPE: integer (Boolean) + DEFAULT: 1 + DESC: Auto Gain Control enable. This feature is not yet implemented. + + NAME: autoexp + TYPE: integer (Boolean) + DEFAULT: 1 + DESC: Auto Exposure Control enable. This feature is not yet implemented. + + NAME: debug + TYPE: integer (0-6) + DEFAULT: 3 + DESC: Sets the threshold for printing debug messages. The higher the value, + the more is printed. The levels are cumulative, and are as follows: + 0=no debug messages + 1=init/detection/unload and other significant messages + 2=some warning messages + 3=config/control function calls + 4=most function calls and data parsing messages + 5=highly repetitive mesgs + + NAME: snapshot + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: Set to 1 to enable snapshot mode. read()/VIDIOCSYNC will block until + the snapshot button is pressed. Note: enabling this mode disables + /proc/video/ov511//button + + NAME: cams + TYPE: integer (1-4 for OV511, 1-31 for OV511+) + DEFAULT: 1 + DESC: Number of cameras allowed to stream simultaneously on a single bus. + Values higher than 1 reduce the data rate of each camera, allowing two + or more to be used at once. If you have a complicated setup involving + both OV511 and OV511+ cameras, trial-and-error may be necessary for + finding the optimum setting. + + NAME: compress + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: Set this to 1 to turn on the camera's compression engine. This can + potentially increase the frame rate at the expense of quality, if you + have a fast CPU. You must load the proper compression module for your + camera before starting your application (ov511_decomp or ov518_decomp). + + NAME: testpat + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: This configures the camera's sensor to transmit a colored test-pattern + instead of an image. This does not work correctly yet. + + NAME: dumppix + TYPE: integer (0-2) + DEFAULT: 0 + DESC: Dumps raw pixel data and skips post-processing and format conversion. + It is for debugging purposes only. Options are: + 0: Disable (default) + 1: Dump raw data from camera, excluding headers and trailers + 2: Dumps data exactly as received from camera + + NAME: led + TYPE: integer (0-2) + DEFAULT: 1 (Always on) + DESC: Controls whether the LED (the little light) on the front of the camera + is always off (0), always on (1), or only on when driver is open (2). + This is not supported with the OV511, and might only work with certain + cameras (ones that actually have the LED wired to the control pin, and + not just hard-wired to be on all the time). + + NAME: dump_bridge + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: Dumps the bridge (OV511[+] or OV518[+]) register values to the system + log. Only useful for serious debugging/development purposes. + + NAME: dump_sensor + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: Dumps the sensor register values to the system log. Only useful for + serious debugging/development purposes. + + NAME: printph + TYPE: integer (Boolean) + DEFAULT: 0 + DESC: Setting this to 1 will dump the first 12 bytes of each isoc frame. This + is only useful if you are trying to debug problems with the isoc data + stream (i.e.: camera initializes, but vidcat hangs until Ctrl-C). Be + warned that this dumps a large number of messages to your kernel log. + + NAME: phy, phuv, pvy, pvuv, qhy, qhuv, qvy, qvuv + TYPE: integer (0-63 for phy and phuv, 0-255 for rest) + DEFAULT: OV511 default values + DESC: These are registers 70h - 77h of the OV511, which control the + prediction ranges and quantization thresholds of the compressor, for + the Y and UV channels in the horizontal and vertical directions. See + the OV511 or OV511+ data sheet for more detailed descriptions. These + normally do not need to be changed. + + NAME: lightfreq + TYPE: integer (0, 50, or 60) + DEFAULT: 0 (use sensor default) + DESC: Sets the sensor to match your lighting frequency. This can reduce the + appearance of "banding", i.e. horizontal lines or waves of light and + dark that are often caused by artificial lighting. Valid values are: + 0 - Use default (depends on sensor, most likely 60 Hz) + 50 - For European and Asian 50 Hz power + 60 - For American 60 Hz power + + NAME: bandingfilter + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Enables the sensorīs banding filter exposure algorithm. This reduces + or stabilizes the "banding" caused by some artificial light sources + (especially fluorescent). You might have to set lightfreq correctly for + this to work right. As an added bonus, this sometimes makes it + possible to capture your monitorīs output. + + NAME: fastset + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Allows picture settings (brightness, contrast, color, and hue) to take + effect immediately, even in the middle of a frame. This reduces the + time to change settings, but can ruin frames during the change. Only + affects OmniVision sensors. + + NAME: force_palette + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Forces the palette (color format) to a specific value. If an + application requests a different palette, it will be rejected, thereby + forcing it to try others until it succeeds. This is useful for forcing + greyscale mode with a color camera, for example. Supported modes are: + 0 (Allows all the following formats) + 1 VIDEO_PALETTE_GREY (Linear greyscale) + 10 VIDEO_PALETTE_YUV420 (YUV 4:2:0 Planar) + 15 VIDEO_PALETTE_YUV420P (YUV 4:2:0 Planar, same as 10) + + NAME: backlight + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Setting this flag changes the exposure algorithm for OmniVision sensors + such that objects in the camera's view (i.e. your head) can be clearly + seen when they are illuminated from behind. It reduces or eliminates + the sensor's auto-exposure function, so it should only be used when + needed. Additionally, it is only supported with the OV6620 and OV7620. + + NAME: unit_video + TYPE: Up to 16 comma-separated integers + DEFAULT: 0,0,0... (automatically assign the next available minor(s)) + DESC: You can specify up to 16 minor numbers to be assigned to ov511 devices. + For example, "unit_video=1,3" will make the driver use /dev/video1 and + /dev/video3 for the first two devices it detects. Additional devices + will be assigned automatically starting at the first available device + node (/dev/video0 in this case). Note that you cannot specify 0 as a + minor number. This feature requires kernel version 2.4.5 or higher. + + NAME: remove_zeros + TYPE: integer (Boolean) + DEFAULT: 0 (do not skip any incoming data) + DESC: Setting this to 1 will remove zero-padding from incoming data. This + will compensate for the blocks of corruption that can appear when the + camera cannot keep up with the speed of the USB bus (eg. at low frame + resolutions). This feature is always enabled when compression is on. + + NAME: mirror + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Setting this to 1 will reverse ("mirror") the image horizontally. This + might be necessary if your camera has a custom lens assembly. This has + no effect with video capture devices. + + NAME: ov518_color + TYPE: integer (Boolean) + DEFAULT: 0 (off) + DESC: Enable OV518 color support. This is off by default since it doesn't + work most of the time. If you want to try it, you must also load + ov518_decomp with the "nouv=0" parameter. If you get improper colors or + diagonal lines through the image, restart your video app and try again. + Repeat as necessary. + +WORKING FEATURES: + o Color streaming/capture at most widths and heights that are multiples of 8. + o Monochrome (use force_palette=1 to enable) + o Setting/getting of saturation, contrast, brightness, and hue (only some of + them work the OV7620 and OV7620AE) + o /proc status reporting + o SAA7111A video capture support at 320x240 and 640x480 + o Compression support + o SMP compatibility + +HOW TO CONTACT ME: + +You can email me at mark@alpha.dyndns.org . Please prefix the subject line +with "OV511: " so that I am certain to notice your message. + +CREDITS: + +The code is based in no small part on the CPiA driver by Johannes Erdfelt, +Randy Dunlap, and others. Big thanks to them for their pioneering work on that +and the USB stack. Thanks to Bret Wallach for getting camera reg IO, ISOC, and +image capture working. Thanks to Orion Sky Lawlor, Kevin Moore, and Claudio +Matsuoka for their work as well. diff --git a/Documentation/video4linux/se401.txt b/Documentation/video4linux/se401.txt new file mode 100644 index 000000000000..7b9d1c960a10 --- /dev/null +++ b/Documentation/video4linux/se401.txt @@ -0,0 +1,54 @@ +Linux driver for SE401 based USB cameras + +Copyright, 2001, Jeroen Vreeken + + +INTRODUCTION: + +The SE401 chip is the used in low-cost usb webcams. +It is produced by Endpoints Inc. (www.endpoints.com). +It interfaces directly to a cmos image sensor and USB. The only other major +part in a se401 based camera is a dram chip. + +The following cameras are known to work with this driver: + +Aox se401 (non-branded) cameras +Philips PVCV665 USB VGA webcam 'Vesta Fun' +Kensington VideoCAM PC Camera Model 67014 +Kensington VideoCAM PC Camera Model 67015 +Kensington VideoCAM PC Camera Model 67016 +Kensington VideoCAM PC Camera Model 67017 + + +WHAT YOU NEED: + +- USB support +- VIDEO4LINUX support + +More information about USB support for linux can be found at: +http://www.linux-usb.org + + +MODULE OPTIONS: + +When the driver is compiled as a module you can also use the 'flickerless' +option. With it exposure is limited to values that do not interfere with the +net frequency. Valid options for this option are 0, 50 and 60. (0=disable, +50=50hz, 60=60hz) + + +KNOWN PROBLEMS: + +The driver works fine with the usb-ohci and uhci host controller drivers, +the default settings also work with usb-uhci. But sending more than one bulk +transfer at a time with usb-uhci doesn't work yet. +Users of usb-ohci and uhci can safely enlarge SE401_NUMSBUF in se401.h in +order to increase the throughput (and thus framerate). + + +HELP: + +The latest info on this driver can be found at: +http://www.chello.nl/~j.vreeken/se401/ +And questions to me can be send to: +pe1rxq@amsat.org diff --git a/Documentation/video4linux/sn9c102.txt b/Documentation/video4linux/sn9c102.txt new file mode 100644 index 000000000000..142920bc011f --- /dev/null +++ b/Documentation/video4linux/sn9c102.txt @@ -0,0 +1,518 @@ + + SN9C10x PC Camera Controllers + Driver for Linux + ============================= + + - Documentation - + + +Index +===== +1. Copyright +2. Disclaimer +3. License +4. Overview and features +5. Module dependencies +6. Module loading +7. Module parameters +8. Optional device control through "sysfs" +9. Supported devices +10. Notes for V4L2 application developers +11. Video frame formats +12. Contact information +13. Credits + + +1. Copyright +============ +Copyright (C) 2004-2006 by Luca Risolia + + +2. Disclaimer +============= +SONiX is a trademark of SONiX Technology Company Limited, inc. +This software is not sponsored or developed by SONiX. + + +3. License +========== +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + +4. Overview and features +======================== +This driver attempts to support the video interface of the devices mounting the +SONiX SN9C101, SN9C102 and SN9C103 PC Camera Controllers. + +It's worth to note that SONiX has never collaborated with the author during the +development of this project, despite several requests for enough detailed +specifications of the register tables, compression engine and video data format +of the above chips. Nevertheless, these informations are no longer necessary, +becouse all the aspects related to these chips are known and have been +described in detail in this documentation. + +The driver relies on the Video4Linux2 and USB core modules. It has been +designed to run properly on SMP systems as well. + +The latest version of the SN9C10x driver can be found at the following URL: +http://www.linux-projects.org/ + +Some of the features of the driver are: + +- full compliance with the Video4Linux2 API (see also "Notes for V4L2 + application developers" paragraph); +- available mmap or read/poll methods for video streaming through isochronous + data transfers; +- automatic detection of image sensor; +- support for built-in microphone interface; +- support for any window resolutions and optional panning within the maximum + pixel area of image sensor; +- image downscaling with arbitrary scaling factors from 1, 2 and 4 in both + directions (see "Notes for V4L2 application developers" paragraph); +- two different video formats for uncompressed or compressed data in low or + high compression quality (see also "Notes for V4L2 application developers" + and "Video frame formats" paragraphs); +- full support for the capabilities of many of the possible image sensors that + can be connected to the SN9C10x bridges, including, for istance, red, green, + blue and global gain adjustments and exposure (see "Supported devices" + paragraph for details); +- use of default color settings for sunlight conditions; +- dynamic I/O interface for both SN9C10x and image sensor control and + monitoring (see "Optional device control through 'sysfs'" paragraph); +- dynamic driver control thanks to various module parameters (see "Module + parameters" paragraph); +- up to 64 cameras can be handled at the same time; they can be connected and + disconnected from the host many times without turning off the computer, if + the system supports hotplugging; +- no known bugs. + + +5. Module dependencies +====================== +For it to work properly, the driver needs kernel support for Video4Linux and +USB. + +The following options of the kernel configuration file must be enabled and +corresponding modules must be compiled: + + # Multimedia devices + # + CONFIG_VIDEO_DEV=m + +To enable advanced debugging functionality on the device through /sysfs: + + # Multimedia devices + # + CONFIG_VIDEO_ADV_DEBUG=y + + # USB support + # + CONFIG_USB=m + +In addition, depending on the hardware being used, the modules below are +necessary: + + # USB Host Controller Drivers + # + CONFIG_USB_EHCI_HCD=m + CONFIG_USB_UHCI_HCD=m + CONFIG_USB_OHCI_HCD=m + +The SN9C103 controller also provides a built-in microphone interface. It is +supported by the USB Audio driver thanks to the ALSA API: + + # Sound + # + CONFIG_SOUND=y + + # Advanced Linux Sound Architecture + # + CONFIG_SND=m + + # USB devices + # + CONFIG_SND_USB_AUDIO=m + +And finally: + + # USB Multimedia devices + # + CONFIG_USB_SN9C102=m + + +6. Module loading +================= +To use the driver, it is necessary to load the "sn9c102" module into memory +after every other module required: "videodev", "usbcore" and, depending on +the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". + +Loading can be done as shown below: + + [root@localhost home]# modprobe sn9c102 + +At this point the devices should be recognized. You can invoke "dmesg" to +analyze kernel messages and verify that the loading process has gone well: + + [user@localhost home]$ dmesg + + +7. Module parameters +==================== +Module parameters are listed below: +------------------------------------------------------------------------------- +Name: video_nr +Type: short array (min = 0, max = 64) +Syntax: <-1|n[,...]> +Description: Specify V4L2 minor mode number: + -1 = use next available + n = use minor number n + You can specify up to 64 cameras this way. + For example: + video_nr=-1,2,-1 would assign minor number 2 to the second + recognized camera and use auto for the first one and for every + other camera. +Default: -1 +------------------------------------------------------------------------------- +Name: force_munmap +Type: bool array (min = 0, max = 64) +Syntax: <0|1[,...]> +Description: Force the application to unmap previously mapped buffer memory + before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not + all the applications support this feature. This parameter is + specific for each detected camera. + 0 = do not force memory unmapping + 1 = force memory unmapping (save memory) +Default: 0 +------------------------------------------------------------------------------- +Name: frame_timeout +Type: uint array (min = 0, max = 64) +Syntax: +Description: Timeout for a video frame in seconds. This parameter is + specific for each detected camera. This parameter can be + changed at runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- +Name: debug +Type: ushort +Syntax: +Description: Debugging information level, from 0 to 3: + 0 = none (use carefully) + 1 = critical errors + 2 = significant informations + 3 = more verbose messages + Level 3 is useful for testing only, when only one device + is used. It also shows some more informations about the + hardware being detected. This parameter can be changed at + runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- + + +8. Optional device control through "sysfs" [1] +========================================== +If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, +it is possible to read and write both the SN9C10x and the image sensor +registers by using the "sysfs" filesystem interface. + +Every time a supported device is recognized, a write-only file named "green" is +created in the /sys/class/video4linux/videoX directory. You can set the green +channel's gain by writing the desired value to it. The value may range from 0 +to 15 for SN9C101 or SN9C102 bridges, from 0 to 127 for SN9C103 bridges. +Similarly, only for SN9C103 controllers, blue and red gain control files are +available in the same directory, for which accepted values may range from 0 to +127. + +There are other four entries in the directory above for each registered camera: +"reg", "val", "i2c_reg" and "i2c_val". The first two files control the +SN9C10x bridge, while the other two control the sensor chip. "reg" and +"i2c_reg" hold the values of the current register index where the following +reading/writing operations are addressed at through "val" and "i2c_val". Their +use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not +be created if the sensor does not actually support the standard I2C protocol or +its registers are not 8-bit long. Also, remember that you must be logged in as +root before writing to them. + +As an example, suppose we were to want to read the value contained in the +register number 1 of the sensor register table - which is usually the product +identifier - of the camera registered as "/dev/video0": + + [root@localhost #] cd /sys/class/video4linux/video0 + [root@localhost #] echo 1 > i2c_reg + [root@localhost #] cat i2c_val + +Note that "cat" will fail if sensor registers cannot be read. + +Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2: + + [root@localhost #] echo 0x11 > reg + [root@localhost #] echo 2 > val + +Note that the SN9C10x always returns 0 when some of its registers are read. +To avoid race conditions, all the I/O accesses to the above files are +serialized. + +The sysfs interface also provides the "frame_header" entry, which exports the +frame header of the most recent requested and captured video frame. The header +is always 18-bytes long and is appended to every video frame by the SN9C10x +controllers. As an example, this additional information can be used by the user +application for implementing auto-exposure features via software. + +The following table describes the frame header: + +Byte # Value Description +------ ----- ----------- +0x00 0xFF Frame synchronisation pattern. +0x01 0xFF Frame synchronisation pattern. +0x02 0x00 Frame synchronisation pattern. +0x03 0xC4 Frame synchronisation pattern. +0x04 0xC4 Frame synchronisation pattern. +0x05 0x96 Frame synchronisation pattern. +0x06 0xXX Unknown meaning. The exact value depends on the chip; + possible values are 0x00, 0x01 and 0x20. +0x07 0xXX Variable value, whose bits are ff00uzzc, where ff is a + frame counter, u is unknown, zz is a size indicator + (00 = VGA, 01 = SIF, 10 = QSIF) and c stands for + "compression enabled" (1 = yes, 0 = no). +0x08 0xXX Brightness sum inside Auto-Exposure area (low-byte). +0x09 0xXX Brightness sum inside Auto-Exposure area (high-byte). + For a pure white image, this number will be equal to 500 + times the area of the specified AE area. For images + that are not pure white, the value scales down according + to relative whiteness. +0x0A 0xXX Brightness sum outside Auto-Exposure area (low-byte). +0x0B 0xXX Brightness sum outside Auto-Exposure area (high-byte). + For a pure white image, this number will be equal to 125 + times the area outside of the specified AE area. For + images that are not pure white, the value scales down + according to relative whiteness. + according to relative whiteness. + +The following bytes are used by the SN9C103 bridge only: + +0x0C 0xXX Unknown meaning +0x0D 0xXX Unknown meaning +0x0E 0xXX Unknown meaning +0x0F 0xXX Unknown meaning +0x10 0xXX Unknown meaning +0x11 0xXX Unknown meaning + +The AE area (sx, sy, ex, ey) in the active window can be set by programming the +registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C10x controllers, where one unit +corresponds to 32 pixels. + +[1] Part of the meaning of the frame header has been documented by Bertrik + Sikken. + + +9. Supported devices +==================== +None of the names of the companies as well as their products will be mentioned +here. They have never collaborated with the author, so no advertising. + +From the point of view of a driver, what unambiguously identify a device are +its vendor and product USB identifiers. Below is a list of known identifiers of +devices mounting the SN9C10x PC camera controllers: + +Vendor ID Product ID +--------- ---------- +0x0c45 0x6001 +0x0c45 0x6005 +0x0c45 0x6007 +0x0c45 0x6009 +0x0c45 0x600d +0x0c45 0x6024 +0x0c45 0x6025 +0x0c45 0x6028 +0x0c45 0x6029 +0x0c45 0x602a +0x0c45 0x602b +0x0c45 0x602c +0x0c45 0x602d +0x0c45 0x602e +0x0c45 0x6030 +0x0c45 0x6080 +0x0c45 0x6082 +0x0c45 0x6083 +0x0c45 0x6088 +0x0c45 0x608a +0x0c45 0x608b +0x0c45 0x608c +0x0c45 0x608e +0x0c45 0x608f +0x0c45 0x60a0 +0x0c45 0x60a2 +0x0c45 0x60a3 +0x0c45 0x60a8 +0x0c45 0x60aa +0x0c45 0x60ab +0x0c45 0x60ac +0x0c45 0x60ae +0x0c45 0x60af +0x0c45 0x60b0 +0x0c45 0x60b2 +0x0c45 0x60b3 +0x0c45 0x60b8 +0x0c45 0x60ba +0x0c45 0x60bb +0x0c45 0x60bc +0x0c45 0x60be + +The list above does not imply that all those devices work with this driver: up +until now only the ones that mount the following image sensors are supported; +kernel messages will always tell you whether this is the case: + +Model Manufacturer +----- ------------ +HV7131D Hynix Semiconductor, Inc. +MI-0343 Micron Technology, Inc. +OV7630 OmniVision Technologies, Inc. +PAS106B PixArt Imaging, Inc. +PAS202BCA PixArt Imaging, Inc. +PAS202BCB PixArt Imaging, Inc. +TAS5110C1B Taiwan Advanced Sensor Corporation +TAS5130D1B Taiwan Advanced Sensor Corporation + +All the available control settings of each image sensor are supported through +the V4L2 interface. + +Donations of new models for further testing and support would be much +appreciated. Non-available hardware will not be supported by the author of this +driver. + + +10. Notes for V4L2 application developers +========================================= +This driver follows the V4L2 API specifications. In particular, it enforces two +rules: + +- exactly one I/O method, either "mmap" or "read", is associated with each +file descriptor. Once it is selected, the application must close and reopen the +device to switch to the other I/O method; + +- although it is not mandatory, previously mapped buffer memory should always +be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. +The same number of buffers as before will be allocated again to match the size +of the new video frames, so you have to map the buffers again before any I/O +attempts on them. + +Consistently with the hardware limits, this driver also supports image +downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions. +However, the V4L2 API specifications don't correctly define how the scaling +factor can be chosen arbitrarily by the "negotiation" of the "source" and +"target" rectangles. To work around this flaw, we have added the convention +that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the +scaling factor is restored to 1. + +This driver supports two different video formats: the first one is the "8-bit +Sequential Bayer" format and can be used to obtain uncompressed video data +from the device through the current I/O method, while the second one provides +"raw" compressed video data (without frame headers not related to the +compressed data). The compression quality may vary from 0 to 1 and can be +selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 +ioctl's. For maximum flexibility, both the default active video format and the +default compression quality depend on how the image sensor being used is +initialized (as described in the documentation of the API for the image sensors +supplied by this driver). + + +11. Video frame formats [1] +======================= +The SN9C10x PC Camera Controllers can send images in two possible video +formats over the USB: either native "Sequential RGB Bayer" or Huffman +compressed. The latter is used to achieve high frame rates. The current video +format may be selected or queried from the user application by calling the +VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 API +specifications. + +The name "Sequential Bayer" indicates the organization of the red, green and +blue pixels in one video frame. Each pixel is associated with a 8-bit long +value and is disposed in memory according to the pattern shown below: + +B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] +G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] +... +... B[(n-1)(m-2)] G[(n-1)(m-1)] +... G[n(m-2)] R[n(m-1)] + +The above matrix also represents the sequential or progressive read-out mode of +the (n, m) Bayer color filter array used in many CCD/CMOS image sensors. + +One compressed video frame consists of a bitstream that encodes for every R, G, +or B pixel the difference between the value of the pixel itself and some +reference pixel value. Pixels are organised in the Bayer pattern and the Bayer +sub-pixels are tracked individually and alternatingly. For example, in the +first line values for the B and G1 pixels are alternatingly encoded, while in +the second line values for the G2 and R pixels are alternatingly encoded. + +The pixel reference value is calculated as follows: +- the 4 top left pixels are encoded in raw uncompressed 8-bit format; +- the value in the top two rows is the value of the pixel left of the current + pixel; +- the value in the left column is the value of the pixel above the current + pixel; +- for all other pixels, the reference value is the average of the value of the + pixel on the left and the value of the pixel above the current pixel; +- there is one code in the bitstream that specifies the value of a pixel + directly (in 4-bit resolution); +- pixel values need to be clamped inside the range [0..255] for proper + decoding. + +The algorithm purely describes the conversion from compressed Bayer code used +in the SN9C10x chips to uncompressed Bayer. Additional steps are required to +convert this to a color image (i.e. a color interpolation algorithm). + +The following Huffman codes have been found: +0: +0 (relative to reference pixel value) +100: +4 +101: -4? +1110xxxx: set absolute value to xxxx.0000 +1101: +11 +1111: -11 +11001: +20 +110000: -20 +110001: ??? - these codes are apparently not used + +[1] The Huffman compression algorithm has been reverse-engineered and + documented by Bertrik Sikken. + + +12. Contact information +======================= +The author may be contacted by e-mail at . + +GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is +'FCE635A4'; the public 1024-bit key should be available at any keyserver; +the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. + + +13. Credits +=========== +Many thanks to following persons for their contribute (listed in alphabetical +order): + +- Luca Capello for the donation of a webcam; +- Philippe Coval for having helped testing the PAS202BCA image sensor; +- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the + donation of a webcam; +- Jon Hollstrom for the donation of a webcam; +- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB + image sensor; +- Stefano Mozzi, who donated 45 EU; +- Andrew Pearce for the donation of a webcam; +- Bertrik Sikken, who reverse-engineered and documented the Huffman compression + algorithm used in the SN9C10x controllers and implemented the first decoder; +- Mizuno Takafumi for the donation of a webcam; +- an "anonymous" donator (who didn't want his name to be revealed) for the + donation of a webcam. diff --git a/Documentation/video4linux/stv680.txt b/Documentation/video4linux/stv680.txt new file mode 100644 index 000000000000..4f8946f32f51 --- /dev/null +++ b/Documentation/video4linux/stv680.txt @@ -0,0 +1,53 @@ +Linux driver for STV0680 based USB cameras + +Copyright, 2001, Kevin Sisson + + +INTRODUCTION: + +STMicroelectronics produces the STV0680B chip, which comes in two +types, -001 and -003. The -003 version allows the recording and downloading +of sound clips from the camera, and allows a flash attachment. Otherwise, +it uses the same commands as the -001 version. Both versions support a +variety of SDRAM sizes and sensors, allowing for a maximum of 26 VGA or 20 +CIF pictures. The STV0680 supports either a serial or a usb interface, and +video is possible through the usb interface. + +The following cameras are known to work with this driver, although any +camera with Vendor/Product codes of 0553/0202 should work: + +Aiptek Pencam (various models) +Nisis QuickPix 2 +Radio Shack 'Kid's digital camera' (#60-1207) +At least one Trust Spycam model +Several other European brand models + +WHAT YOU NEED: + +- USB support +- VIDEO4LINUX support + +More information about USB support for linux can be found at: +http://www.linux-usb.org + + +MODULE OPTIONS: + +When the driver is compiled as a module, you can set a "swapRGB=1" +option, if necessary, for those applications that require it +(such as xawtv). However, the driver should detect and set this +automatically, so this option should not normally be used. + + +KNOWN PROBLEMS: + +The driver seems to work better with the usb-ohci than the usb-uhci host +controller driver. + +HELP: + +The latest info on this driver can be found at: +http://personal.clt.bellsouth.net/~kjsisson or at +http://stv0680-usb.sourceforge.net + +Any questions to me can be send to: kjsisson@bellsouth.net \ No newline at end of file diff --git a/Documentation/video4linux/w9968cf.txt b/Documentation/video4linux/w9968cf.txt new file mode 100644 index 000000000000..3b704f2aae6d --- /dev/null +++ b/Documentation/video4linux/w9968cf.txt @@ -0,0 +1,461 @@ + + W996[87]CF JPEG USB Dual Mode Camera Chip + Driver for Linux 2.6 (basic version) + ========================================= + + - Documentation - + + +Index +===== +1. Copyright +2. Disclaimer +3. License +4. Overview +5. Supported devices +6. Module dependencies +7. Module loading +8. Module paramaters +9. Contact information +10. Credits + + +1. Copyright +============ +Copyright (C) 2002-2004 by Luca Risolia + + +2. Disclaimer +============= +Winbond is a trademark of Winbond Electronics Corporation. +This software is not sponsored or developed by Winbond. + + +3. License +========== +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + +4. Overview +=========== +This driver supports the video streaming capabilities of the devices mounting +Winbond W9967CF and Winbond W9968CF JPEG USB Dual Mode Camera Chips. OV681 +based cameras should be supported as well. + +The driver is divided into two modules: the basic one, "w9968cf", is needed for +the supported devices to work; the second one, "w9968cf-vpp", is an optional +module, which provides some useful video post-processing functions like video +decoding, up-scaling and colour conversions. + +Note that the official kernels do neither include nor support the second +module for performance purposes. Therefore, it is always recommended to +download and install the latest and complete release of the driver, +replacing the existing one, if present. + +The latest and full-featured version of the W996[87]CF driver can be found at: +http://www.linux-projects.org. Please refer to the documentation included in +that package, if you are going to use it. + +Up to 32 cameras can be handled at the same time. They can be connected and +disconnected from the host many times without turning off the computer, if +your system supports the hotplug facility. + +To change the default settings for each camera, many parameters can be passed +through command line when the module is loaded into memory. + +The driver relies on the Video4Linux, USB and I2C core modules. It has been +designed to run properly on SMP systems as well. An additional module, +"ovcamchip", is mandatory; it provides support for some OmniVision image +sensors connected to the W996[87]CF chips; if found in the system, the module +will be automatically loaded by default (provided that the kernel has been +compiled with the automatic module loading option). + + +5. Supported devices +==================== +At the moment, known W996[87]CF and OV681 based devices are: +- Aroma Digi Pen VGA Dual Mode ADG-5000 (unknown image sensor) +- AVerMedia AVerTV USB (SAA7111A, Philips FI1216Mk2 tuner, PT2313L audio chip) +- Creative Labs Video Blaster WebCam Go (OmniVision OV7610 sensor) +- Creative Labs Video Blaster WebCam Go Plus (OmniVision OV7620 sensor) +- Lebon LDC-035A (unknown image sensor) +- Ezonics EZ-802 EZMega Cam (OmniVision OV8610C sensor) +- OmniVision OV8610-EDE (OmniVision OV8610 sensor) +- OPCOM Digi Pen VGA Dual Mode Pen Camera (unknown image sensor) +- Pretec Digi Pen-II (OmniVision OV7620 sensor) +- Pretec DigiPen-480 (OmniVision OV8610 sensor) + +If you know any other W996[87]CF or OV681 based cameras, please contact me. + +The list above does not imply that all those devices work with this driver: up +until now only webcams that have an image sensor supported by the "ovcamchip" +module work. Kernel messages will always tell you whether this is case. + +Possible external microcontrollers of those webcams are not supported: this +means that still images cannot be downloaded from the device memory. + +Furthermore, it's worth to note that I was only able to run tests on my +"Creative Labs Video Blaster WebCam Go". Donations of other models, for +additional testing and full support, would be much appreciated. + + +6. Module dependencies +====================== +For it to work properly, the driver needs kernel support for Video4Linux, USB +and I2C, and the "ovcamchip" module for the image sensor. Make sure you are not +actually using any external "ovcamchip" module, given that the W996[87]CF +driver depends on the version of the module present in the official kernels. + +The following options of the kernel configuration file must be enabled and +corresponding modules must be compiled: + + # Multimedia devices + # + CONFIG_VIDEO_DEV=m + + # I2C support + # + CONFIG_I2C=m + +The I2C core module can be compiled statically in the kernel as well. + + # OmniVision Camera Chip support + # + CONFIG_VIDEO_OVCAMCHIP=m + + # USB support + # + CONFIG_USB=m + +In addition, depending on the hardware being used, only one of the modules +below is necessary: + + # USB Host Controller Drivers + # + CONFIG_USB_EHCI_HCD=m + CONFIG_USB_UHCI_HCD=m + CONFIG_USB_OHCI_HCD=m + +And finally: + + # USB Multimedia devices + # + CONFIG_USB_W9968CF=m + + +7. Module loading +================= +To use the driver, it is necessary to load the "w9968cf" module into memory +after every other module required. + +Loading can be done this way, from root: + + [root@localhost home]# modprobe usbcore + [root@localhost home]# modprobe i2c-core + [root@localhost home]# modprobe videodev + [root@localhost home]# modprobe w9968cf + +At this point the pertinent devices should be recognized: "dmesg" can be used +to analyze kernel messages: + + [user@localhost home]$ dmesg + +There are a lot of parameters the module can use to change the default +settings for each device. To list every possible parameter with a brief +explanation about them and which syntax to use, it is recommended to run the +"modinfo" command: + + [root@locahost home]# modinfo w9968cf + + +8. Module parameters +==================== +Module parameters are listed below: +------------------------------------------------------------------------------- +Name: ovmod_load +Type: bool +Syntax: <0|1> +Description: Automatic 'ovcamchip' module loading: 0 disabled, 1 enabled. + If enabled, 'insmod' searches for the required 'ovcamchip' + module in the system, according to its configuration, and + loads that module automatically. This action is performed as + once soon as the 'w9968cf' module is loaded into memory. +Default: 1 +Note: The kernel must be compiled with the CONFIG_KMOD option + enabled for the 'ovcamchip' module to be loaded and for + this parameter to be present. +------------------------------------------------------------------------------- +Name: simcams +Type: int +Syntax: +Description: Number of cameras allowed to stream simultaneously. + n may vary from 0 to 32. +Default: 32 +------------------------------------------------------------------------------- +Name: video_nr +Type: int array (min = 0, max = 32) +Syntax: <-1|n[,...]> +Description: Specify V4L minor mode number. + -1 = use next available + n = use minor number n + You can specify up to 32 cameras this way. + For example: + video_nr=-1,2,-1 would assign minor number 2 to the second + recognized camera and use auto for the first one and for every + other camera. +Default: -1 +------------------------------------------------------------------------------- +Name: packet_size +Type: int array (min = 0, max = 32) +Syntax: +Description: Specify the maximum data payload size in bytes for alternate + settings, for each device. n is scaled between 63 and 1023. +Default: 1023 +------------------------------------------------------------------------------- +Name: max_buffers +Type: int array (min = 0, max = 32) +Syntax: +Description: For advanced users. + Specify the maximum number of video frame buffers to allocate + for each device, from 2 to 32. +Default: 2 +------------------------------------------------------------------------------- +Name: double_buffer +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Hardware double buffering: 0 disabled, 1 enabled. + It should be enabled if you want smooth video output: if you + obtain out of sync. video, disable it, or try to + decrease the 'clockdiv' module parameter value. +Default: 1 for every device. +------------------------------------------------------------------------------- +Name: clamping +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Video data clamping: 0 disabled, 1 enabled. +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: filter_type +Type: int array (min = 0, max = 32) +Syntax: <0|1|2[,...]> +Description: Video filter type. + 0 none, 1 (1-2-1) 3-tap filter, 2 (2-3-6-3-2) 5-tap filter. + The filter is used to reduce noise and aliasing artifacts + produced by the CCD or CMOS image sensor. +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: largeview +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Large view: 0 disabled, 1 enabled. +Default: 1 for every device. +------------------------------------------------------------------------------- +Name: upscaling +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Software scaling (for non-compressed video only): + 0 disabled, 1 enabled. + Disable it if you have a slow CPU or you don't have enough + memory. +Default: 0 for every device. +Note: If 'w9968cf-vpp' is not present, this parameter is set to 0. +------------------------------------------------------------------------------- +Name: decompression +Type: int array (min = 0, max = 32) +Syntax: <0|1|2[,...]> +Description: Software video decompression: + 0 = disables decompression + (doesn't allow formats needing decompression). + 1 = forces decompression + (allows formats needing decompression only). + 2 = allows any permitted formats. + Formats supporting (de)compressed video are YUV422P and + YUV420P/YUV420 in any resolutions where width and height are + multiples of 16. +Default: 2 for every device. +Note: If 'w9968cf-vpp' is not present, forcing decompression is not + allowed; in this case this parameter is set to 2. +------------------------------------------------------------------------------- +Name: force_palette +Type: int array (min = 0, max = 32) +Syntax: <0|9|10|13|15|8|7|1|6|3|4|5[,...]> +Description: Force picture palette. + In order: + 0 = Off - allows any of the following formats: + 9 = UYVY 16 bpp - Original video, compression disabled + 10 = YUV420 12 bpp - Original video, compression enabled + 13 = YUV422P 16 bpp - Original video, compression enabled + 15 = YUV420P 12 bpp - Original video, compression enabled + 8 = YUVY 16 bpp - Software conversion from UYVY + 7 = YUV422 16 bpp - Software conversion from UYVY + 1 = GREY 8 bpp - Software conversion from UYVY + 6 = RGB555 16 bpp - Software conversion from UYVY + 3 = RGB565 16 bpp - Software conversion from UYVY + 4 = RGB24 24 bpp - Software conversion from UYVY + 5 = RGB32 32 bpp - Software conversion from UYVY + When not 0, this parameter will override 'decompression'. +Default: 0 for every device. Initial palette is 9 (UYVY). +Note: If 'w9968cf-vpp' is not present, this parameter is set to 9. +------------------------------------------------------------------------------- +Name: force_rgb +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Read RGB video data instead of BGR: + 1 = use RGB component ordering. + 0 = use BGR component ordering. + This parameter has effect when using RGBX palettes only. +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: autobright +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Image sensor automatically changes brightness: + 0 = no, 1 = yes +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: autoexp +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Image sensor automatically changes exposure: + 0 = no, 1 = yes +Default: 1 for every device. +------------------------------------------------------------------------------- +Name: lightfreq +Type: int array (min = 0, max = 32) +Syntax: <50|60[,...]> +Description: Light frequency in Hz: + 50 for European and Asian lighting, 60 for American lighting. +Default: 50 for every device. +------------------------------------------------------------------------------- +Name: bandingfilter +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Banding filter to reduce effects of fluorescent + lighting: + 0 disabled, 1 enabled. + This filter tries to reduce the pattern of horizontal + light/dark bands caused by some (usually fluorescent) lighting. +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: clockdiv +Type: int array (min = 0, max = 32) +Syntax: <-1|n[,...]> +Description: Force pixel clock divisor to a specific value (for experts): + n may vary from 0 to 127. + -1 for automatic value. + See also the 'double_buffer' module parameter. +Default: -1 for every device. +------------------------------------------------------------------------------- +Name: backlight +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Objects are lit from behind: + 0 = no, 1 = yes +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: mirror +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: Reverse image horizontally: + 0 = no, 1 = yes +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: monochrome +Type: bool array (min = 0, max = 32) +Syntax: <0|1[,...]> +Description: The image sensor is monochrome: + 0 = no, 1 = yes +Default: 0 for every device. +------------------------------------------------------------------------------- +Name: brightness +Type: long array (min = 0, max = 32) +Syntax: +Description: Set picture brightness (0-65535). + This parameter has no effect if 'autobright' is enabled. +Default: 31000 for every device. +------------------------------------------------------------------------------- +Name: hue +Type: long array (min = 0, max = 32) +Syntax: +Description: Set picture hue (0-65535). +Default: 32768 for every device. +------------------------------------------------------------------------------- +Name: colour +Type: long array (min = 0, max = 32) +Syntax: +Description: Set picture saturation (0-65535). +Default: 32768 for every device. +------------------------------------------------------------------------------- +Name: contrast +Type: long array (min = 0, max = 32) +Syntax: +Description: Set picture contrast (0-65535). +Default: 50000 for every device. +------------------------------------------------------------------------------- +Name: whiteness +Type: long array (min = 0, max = 32) +Syntax: +Description: Set picture whiteness (0-65535). +Default: 32768 for every device. +------------------------------------------------------------------------------- +Name: debug +Type: int +Syntax: +Description: Debugging information level, from 0 to 6: + 0 = none (use carefully) + 1 = critical errors + 2 = significant informations + 3 = configuration or general messages + 4 = warnings + 5 = called functions + 6 = function internals + Level 5 and 6 are useful for testing only, when only one + device is used. +Default: 2 +------------------------------------------------------------------------------- +Name: specific_debug +Type: bool +Syntax: <0|1> +Description: Enable or disable specific debugging messages: + 0 = print messages concerning every level <= 'debug' level. + 1 = print messages concerning the level indicated by 'debug'. +Default: 0 +------------------------------------------------------------------------------- + + +9. Contact information +====================== +I may be contacted by e-mail at . + +I can accept GPG/PGP encrypted e-mail. My GPG key ID is 'FCE635A4'. +My public 1024-bit key should be available at your keyserver; the fingerprint +is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. + + +10. Credits +========== +The development would not have proceed much further without having looked at +the source code of other drivers and without the help of several persons; in +particular: + +- the I2C interface to kernel and high-level image sensor control routines have + been taken from the OV511 driver by Mark McClelland; + +- memory management code has been copied from the bttv driver by Ralph Metzler, + Marcus Metzler and Gerd Knorr; + +- the low-level I2C read function has been written by Frederic Jouault; + +- the low-level I2C fast write function has been written by Piotr Czerczak. diff --git a/Documentation/video4linux/zc0301.txt b/Documentation/video4linux/zc0301.txt new file mode 100644 index 000000000000..f55262c6733b --- /dev/null +++ b/Documentation/video4linux/zc0301.txt @@ -0,0 +1,254 @@ + + ZC0301 Image Processor and Control Chip + Driver for Linux + ======================================= + + - Documentation - + + +Index +===== +1. Copyright +2. Disclaimer +3. License +4. Overview and features +5. Module dependencies +6. Module loading +7. Module parameters +8. Supported devices +9. Notes for V4L2 application developers +10. Contact information +11. Credits + + +1. Copyright +============ +Copyright (C) 2006 by Luca Risolia + + +2. Disclaimer +============= +This software is not developed or sponsored by Z-Star Microelectronics Corp. +Trademarks are property of their respective owner. + + +3. License +========== +This program is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + +4. Overview and features +======================== +This driver supports the video interface of the devices mounting the ZC0301 +Image Processor and Control Chip. + +The driver relies on the Video4Linux2 and USB core modules. It has been +designed to run properly on SMP systems as well. + +The latest version of the ZC0301 driver can be found at the following URL: +http://www.linux-projects.org/ + +Some of the features of the driver are: + +- full compliance with the Video4Linux2 API (see also "Notes for V4L2 + application developers" paragraph); +- available mmap or read/poll methods for video streaming through isochronous + data transfers; +- automatic detection of image sensor; +- video format is standard JPEG; +- dynamic driver control thanks to various module parameters (see "Module + parameters" paragraph); +- up to 64 cameras can be handled at the same time; they can be connected and + disconnected from the host many times without turning off the computer, if + the system supports hotplugging; + + +5. Module dependencies +====================== +For it to work properly, the driver needs kernel support for Video4Linux and +USB. + +The following options of the kernel configuration file must be enabled and +corresponding modules must be compiled: + + # Multimedia devices + # + CONFIG_VIDEO_DEV=m + + # USB support + # + CONFIG_USB=m + +In addition, depending on the hardware being used, the modules below are +necessary: + + # USB Host Controller Drivers + # + CONFIG_USB_EHCI_HCD=m + CONFIG_USB_UHCI_HCD=m + CONFIG_USB_OHCI_HCD=m + +The ZC0301 controller also provides a built-in microphone interface. It is +supported by the USB Audio driver thanks to the ALSA API: + + # Sound + # + CONFIG_SOUND=y + + # Advanced Linux Sound Architecture + # + CONFIG_SND=m + + # USB devices + # + CONFIG_SND_USB_AUDIO=m + +And finally: + + # USB Multimedia devices + # + CONFIG_USB_ZC0301=m + + +6. Module loading +================= +To use the driver, it is necessary to load the "zc0301" module into memory +after every other module required: "videodev", "usbcore" and, depending on +the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". + +Loading can be done as shown below: + + [root@localhost home]# modprobe zc0301 + +At this point the devices should be recognized. You can invoke "dmesg" to +analyze kernel messages and verify that the loading process has gone well: + + [user@localhost home]$ dmesg + + +7. Module parameters +==================== +Module parameters are listed below: +------------------------------------------------------------------------------- +Name: video_nr +Type: short array (min = 0, max = 64) +Syntax: <-1|n[,...]> +Description: Specify V4L2 minor mode number: + -1 = use next available + n = use minor number n + You can specify up to 64 cameras this way. + For example: + video_nr=-1,2,-1 would assign minor number 2 to the second + registered camera and use auto for the first one and for every + other camera. +Default: -1 +------------------------------------------------------------------------------- +Name: force_munmap +Type: bool array (min = 0, max = 64) +Syntax: <0|1[,...]> +Description: Force the application to unmap previously mapped buffer memory + before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not + all the applications support this feature. This parameter is + specific for each detected camera. + 0 = do not force memory unmapping + 1 = force memory unmapping (save memory) +Default: 0 +------------------------------------------------------------------------------- +Name: frame_timeout +Type: uint array (min = 0, max = 64) +Syntax: +Description: Timeout for a video frame in seconds. This parameter is + specific for each detected camera. This parameter can be + changed at runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- +Name: debug +Type: ushort +Syntax: +Description: Debugging information level, from 0 to 3: + 0 = none (use carefully) + 1 = critical errors + 2 = significant informations + 3 = more verbose messages + Level 3 is useful for testing only, when only one device + is used at the same time. It also shows some more informations + about the hardware being detected. This module parameter can be + changed at runtime thanks to the /sys filesystem interface. +Default: 2 +------------------------------------------------------------------------------- + + +8. Supported devices +==================== +None of the names of the companies as well as their products will be mentioned +here. They have never collaborated with the author, so no advertising. + +From the point of view of a driver, what unambiguously identify a device are +its vendor and product USB identifiers. Below is a list of known identifiers of +devices mounting the ZC0301 Image Processor and Control Chips: + +Vendor ID Product ID +--------- ---------- +0x041e 0x4017 +0x041e 0x401c +0x041e 0x401e +0x041e 0x4034 +0x041e 0x4035 +0x046d 0x08ae +0x0ac8 0x0301 +0x10fd 0x8050 + +The list above does not imply that all those devices work with this driver: up +until now only the ones that mount the following image sensors are supported; +kernel messages will always tell you whether this is the case: + +Model Manufacturer +----- ------------ +PAS202BCB PixArt Imaging, Inc. + + +9. Notes for V4L2 application developers +======================================== +This driver follows the V4L2 API specifications. In particular, it enforces two +rules: + +- exactly one I/O method, either "mmap" or "read", is associated with each +file descriptor. Once it is selected, the application must close and reopen the +device to switch to the other I/O method; + +- although it is not mandatory, previously mapped buffer memory should always +be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. +The same number of buffers as before will be allocated again to match the size +of the new video frames, so you have to map the buffers again before any I/O +attempts on them. + + +10. Contact information +======================= +The author may be contacted by e-mail at . + +GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is +'FCE635A4'; the public 1024-bit key should be available at any keyserver; +the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. + + +11. Credits +=========== +- Informations about the chip internals needed to enable the I2C protocol have + been taken from the documentation of the ZC030x Video4Linux1 driver written + by Andrew Birkett ; +- The initialization values of the ZC0301 controller connected to the PAS202BCB + image sensor have been taken from the SPCA5XX driver maintained by + Michel Xhaard . -- cgit v1.2.2 From a580290c3e64bb695158a090d02d1232d9609311 Mon Sep 17 00:00:00 2001 From: Martin Waitz Date: Sun, 2 Apr 2006 13:59:55 +0200 Subject: Documentation: fix minor kernel-doc warnings This patch updates the comments to match the actual code. Signed-off-by: Martin Waitz Signed-off-by: Adrian Bunk --- Documentation/DocBook/kernel-api.tmpl | 1 - 1 file changed, 1 deletion(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl index 8c9c6704e85b..ca02e04a906c 100644 --- a/Documentation/DocBook/kernel-api.tmpl +++ b/Documentation/DocBook/kernel-api.tmpl @@ -322,7 +322,6 @@ X!Earch/i386/kernel/mca.c The Filesystem for Exporting Kernel Objects !Efs/sysfs/file.c -!Efs/sysfs/dir.c !Efs/sysfs/symlink.c !Efs/sysfs/bin.c -- cgit v1.2.2