diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-23 16:35:19 -0500 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-23 16:35:19 -0500 |
commit | 17a3be341e55b49e4579634281b86f1eb0bad8e8 (patch) | |
tree | 7c2857db7afb9b0fca2a15b1602333b2c5125780 /Documentation | |
parent | f793067eb91afa37904d33075bd44fd8b2774b8a (diff) | |
parent | 37e9066b2f85480d99d3795373f5ef0b00ac1189 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (30 commits)
USB: Fix a bug on appledisplay.c regarding signedness
USB: option: support hi speed for modem Haier CE100
USB: audio gadget: free alsa devices when unloading
USB: audio gadget: fix wTotalLength calculation
usb: otg: isp1301_omap: fix compile error
USB: musb: workaround Blackfin FIFO anomalies
USB: musb: Fix array index out of bounds issue
USB: musb: Fix null pointer dereference issue
USB: musb: correct DMA address for tx
USB: musb: gadget_ep0: avoid SetupEnd interrupt
USB: musb: fix for crash in DM646x USB when (CPPI)DMA is enabled
USB: musb: do not work if no gadget driver is loaded
USB: musb: gadget: set otg tranceiver to idle when registering gadget
USB: musb: Populate the VBUS GPIO with the correct GPIO number
USB: musb: MAINTAINERS: Fix my tree's address
USB: musb: fix compiling warning with min() macro
USB: musb: move musb_remove to __exit
USB: musb_gadget: fix kernel oops in txstate()
USB: ftdi_sio: sort PID/VID entries in new ftdi_sio_ids.h header
USB: ftdi_sio: isolate all device IDs to new ftdi_sio_ids.h header
...
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 18 | ||||
-rw-r--r-- | Documentation/usb/power-management.txt | 41 |
2 files changed, 25 insertions, 34 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index deb6b489e4e5..a07c0f366f91 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb | |||
@@ -21,25 +21,27 @@ Contact: Alan Stern <stern@rowland.harvard.edu> | |||
21 | Description: | 21 | Description: |
22 | Each USB device directory will contain a file named | 22 | Each USB device directory will contain a file named |
23 | power/level. This file holds a power-level setting for | 23 | power/level. This file holds a power-level setting for |
24 | the device, one of "on", "auto", or "suspend". | 24 | the device, either "on" or "auto". |
25 | 25 | ||
26 | "on" means that the device is not allowed to autosuspend, | 26 | "on" means that the device is not allowed to autosuspend, |
27 | although normal suspends for system sleep will still | 27 | although normal suspends for system sleep will still |
28 | be honored. "auto" means the device will autosuspend | 28 | be honored. "auto" means the device will autosuspend |
29 | and autoresume in the usual manner, according to the | 29 | and autoresume in the usual manner, according to the |
30 | capabilities of its driver. "suspend" means the device | 30 | capabilities of its driver. |
31 | is forced into a suspended state and it will not autoresume | ||
32 | in response to I/O requests. However remote-wakeup requests | ||
33 | from the device may still be enabled (the remote-wakeup | ||
34 | setting is controlled separately by the power/wakeup | ||
35 | attribute). | ||
36 | 31 | ||
37 | During normal use, devices should be left in the "auto" | 32 | During normal use, devices should be left in the "auto" |
38 | level. The other levels are meant for administrative uses. | 33 | level. The "on" level is meant for administrative uses. |
39 | If you want to suspend a device immediately but leave it | 34 | If you want to suspend a device immediately but leave it |
40 | free to wake up in response to I/O requests, you should | 35 | free to wake up in response to I/O requests, you should |
41 | write "0" to power/autosuspend. | 36 | write "0" to power/autosuspend. |
42 | 37 | ||
38 | Device not capable of proper suspend and resume should be | ||
39 | left in the "on" level. Although the USB spec requires | ||
40 | devices to support suspend/resume, many of them do not. | ||
41 | In fact so many don't that by default, the USB core | ||
42 | initializes all non-hub devices in the "on" level. Some | ||
43 | drivers may change this setting when they are bound. | ||
44 | |||
43 | What: /sys/bus/usb/devices/.../power/persist | 45 | What: /sys/bus/usb/devices/.../power/persist |
44 | Date: May 2007 | 46 | Date: May 2007 |
45 | KernelVersion: 2.6.23 | 47 | KernelVersion: 2.6.23 |
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt index c7c1dc2f8017..3bf6818c8cf5 100644 --- a/Documentation/usb/power-management.txt +++ b/Documentation/usb/power-management.txt | |||
@@ -71,12 +71,10 @@ being accessed through sysfs, then it definitely is idle. | |||
71 | Forms of dynamic PM | 71 | Forms of dynamic PM |
72 | ------------------- | 72 | ------------------- |
73 | 73 | ||
74 | Dynamic suspends can occur in two ways: manual and automatic. | 74 | Dynamic suspends occur when the kernel decides to suspend an idle |
75 | "Manual" means that the user has told the kernel to suspend a device, | 75 | device. This is called "autosuspend" for short. In general, a device |
76 | whereas "automatic" means that the kernel has decided all by itself to | 76 | won't be autosuspended unless it has been idle for some minimum period |
77 | suspend a device. Automatic suspend is called "autosuspend" for | 77 | of time, the so-called idle-delay time. |
78 | short. In general, a device won't be autosuspended unless it has been | ||
79 | idle for some minimum period of time, the so-called idle-delay time. | ||
80 | 78 | ||
81 | Of course, nothing the kernel does on its own initiative should | 79 | Of course, nothing the kernel does on its own initiative should |
82 | prevent the computer or its devices from working properly. If a | 80 | prevent the computer or its devices from working properly. If a |
@@ -96,10 +94,11 @@ idle. | |||
96 | We can categorize power management events in two broad classes: | 94 | We can categorize power management events in two broad classes: |
97 | external and internal. External events are those triggered by some | 95 | external and internal. External events are those triggered by some |
98 | agent outside the USB stack: system suspend/resume (triggered by | 96 | agent outside the USB stack: system suspend/resume (triggered by |
99 | userspace), manual dynamic suspend/resume (also triggered by | 97 | userspace), manual dynamic resume (also triggered by userspace), and |
100 | userspace), and remote wakeup (triggered by the device). Internal | 98 | remote wakeup (triggered by the device). Internal events are those |
101 | events are those triggered within the USB stack: autosuspend and | 99 | triggered within the USB stack: autosuspend and autoresume. Note that |
102 | autoresume. | 100 | all dynamic suspend events are internal; external agents are not |
101 | allowed to issue dynamic suspends. | ||
103 | 102 | ||
104 | 103 | ||
105 | The user interface for dynamic PM | 104 | The user interface for dynamic PM |
@@ -145,9 +144,9 @@ relevant attribute files are: wakeup, level, and autosuspend. | |||
145 | number of seconds the device should remain idle before | 144 | number of seconds the device should remain idle before |
146 | the kernel will autosuspend it (the idle-delay time). | 145 | the kernel will autosuspend it (the idle-delay time). |
147 | The default is 2. 0 means to autosuspend as soon as | 146 | The default is 2. 0 means to autosuspend as soon as |
148 | the device becomes idle, and -1 means never to | 147 | the device becomes idle, and negative values mean |
149 | autosuspend. You can write a number to the file to | 148 | never to autosuspend. You can write a number to the |
150 | change the autosuspend idle-delay time. | 149 | file to change the autosuspend idle-delay time. |
151 | 150 | ||
152 | Writing "-1" to power/autosuspend and writing "on" to power/level do | 151 | Writing "-1" to power/autosuspend and writing "on" to power/level do |
153 | essentially the same thing -- they both prevent the device from being | 152 | essentially the same thing -- they both prevent the device from being |
@@ -377,9 +376,9 @@ the device hasn't been idle for long enough, a delayed workqueue | |||
377 | routine is automatically set up to carry out the operation when the | 376 | routine is automatically set up to carry out the operation when the |
378 | autosuspend idle-delay has expired. | 377 | autosuspend idle-delay has expired. |
379 | 378 | ||
380 | Autoresume attempts also can fail. This will happen if power/level is | 379 | Autoresume attempts also can fail, although failure would mean that |
381 | set to "suspend" or if the device doesn't manage to resume properly. | 380 | the device is no longer present or operating properly. Unlike |
382 | Unlike autosuspend, there's no delay for an autoresume. | 381 | autosuspend, there's no delay for an autoresume. |
383 | 382 | ||
384 | 383 | ||
385 | Other parts of the driver interface | 384 | Other parts of the driver interface |
@@ -527,13 +526,3 @@ succeed, it may still remain active and thus cause the system to | |||
527 | resume as soon as the system suspend is complete. Or the remote | 526 | resume as soon as the system suspend is complete. Or the remote |
528 | wakeup may fail and get lost. Which outcome occurs depends on timing | 527 | wakeup may fail and get lost. Which outcome occurs depends on timing |
529 | and on the hardware and firmware design. | 528 | and on the hardware and firmware design. |
530 | |||
531 | More interestingly, a device might undergo a manual resume or | ||
532 | autoresume during system suspend. With current kernels this shouldn't | ||
533 | happen, because manual resumes must be initiated by userspace and | ||
534 | autoresumes happen in response to I/O requests, but all user processes | ||
535 | and I/O should be quiescent during a system suspend -- thanks to the | ||
536 | freezer. However there are plans to do away with the freezer, which | ||
537 | would mean these things would become possible. If and when this comes | ||
538 | about, the USB core will carefully arrange matters so that either type | ||
539 | of resume will block until the entire system has resumed. | ||