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authorLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 00:47:18 -0500
committerLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-29 00:47:18 -0500
commit0a8c5395f90f06d128247844b2515c8bf3f2826b (patch)
treed95382dcdfa303b99d480c01763d6cb6767fdaca /Documentation/sound/alsa/HD-Audio.txt
parent25051158bbed127e8672b43396c71c5eb610e5f1 (diff)
parent3c92ec8ae91ecf59d88c798301833d7cf83f2179 (diff)
[XFS] Fix merge failures
Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 Conflicts: fs/xfs/linux-2.6/xfs_cred.h fs/xfs/linux-2.6/xfs_globals.h fs/xfs/linux-2.6/xfs_ioctl.c fs/xfs/xfs_vnodeops.h Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
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1MORE NOTES ON HD-AUDIO DRIVER
2=============================
3 Takashi Iwai <tiwai@suse.de>
4
5
6GENERAL
7-------
8
9HD-audio is the new standard on-board audio component on modern PCs
10after AC97. Although Linux has been supporting HD-audio since long
11time ago, there are often problems with new machines. A part of the
12problem is broken BIOS, and the rest is the driver implementation.
13This document explains the brief trouble-shooting and debugging
14methods for the HD-audio hardware.
15
16The HD-audio component consists of two parts: the controller chip and
17the codec chips on the HD-audio bus. Linux provides a single driver
18for all controllers, snd-hda-intel. Although the driver name contains
19a word of a well-known harware vendor, it's not specific to it but for
20all controller chips by other companies. Since the HD-audio
21controllers are supposed to be compatible, the single snd-hda-driver
22should work in most cases. But, not surprisingly, there are known
23bugs and issues specific to each controller type. The snd-hda-intel
24driver has a bunch of workarounds for these as described below.
25
26A controller may have multiple codecs. Usually you have one audio
27codec and optionally one modem codec. In theory, there might be
28multiple audio codecs, e.g. for analog and digital outputs, and the
29driver might not work properly because of conflict of mixer elements.
30This should be fixed in future if such hardware really exists.
31
32The snd-hda-intel driver has several different codec parsers depending
33on the codec. It has a generic parser as a fallback, but this
34functionality is fairly limited until now. Instead of the generic
35parser, usually the codec-specific parser (coded in patch_*.c) is used
36for the codec-specific implementations. The details about the
37codec-specific problems are explained in the later sections.
38
39If you are interested in the deep debugging of HD-audio, read the
40HD-audio specification at first. The specification is found on
41Intel's web page, for example:
42
43- http://www.intel.com/standards/hdaudio/
44
45
46HD-AUDIO CONTROLLER
47-------------------
48
49DMA-Position Problem
50~~~~~~~~~~~~~~~~~~~~
51The most common problem of the controller is the inaccurate DMA
52pointer reporting. The DMA pointer for playback and capture can be
53read in two ways, either via a LPIB register or via a position-buffer
54map. As default the driver tries to read from the io-mapped
55position-buffer, and falls back to LPIB if the position-buffer appears
56dead. However, this detection isn't perfect on some devices. In such
57a case, you can change the default method via `position_fix` option.
58
59`position_fix=1` means to use LPIB method explicitly.
60`position_fix=2` means to use the position-buffer. 0 is the default
61value, the automatic check and fallback to LPIB as described in the
62above. If you get a problem of repeated sounds, this option might
63help.
64
65In addition to that, every controller is known to be broken regarding
66the wake-up timing. It wakes up a few samples before actually
67processing the data on the buffer. This caused a lot of problems, for
68example, with ALSA dmix or JACK. Since 2.6.27 kernel, the driver puts
69an artificial delay to the wake up timing. This delay is controlled
70via `bdl_pos_adj` option.
71
72When `bdl_pos_adj` is a negative value (as default), it's assigned to
73an appropriate value depending on the controller chip. For Intel
74chips, it'd be 1 while it'd be 32 for others. Usually this works.
75Only in case it doesn't work and you get warning messages, you should
76change this parameter to other values.
77
78
79Codec-Probing Problem
80~~~~~~~~~~~~~~~~~~~~~
81A less often but a more severe problem is the codec probing. When
82BIOS reports the available codec slots wrongly, the driver gets
83confused and tries to access the non-existing codec slot. This often
84results in the total screw-up, and destructs the further communication
85with the codec chips. The symptom appears usually as error messages
86like:
87------------------------------------------------------------------------
88 hda_intel: azx_get_response timeout, switching to polling mode:
89 last cmd=0x12345678
90 hda_intel: azx_get_response timeout, switching to single_cmd mode:
91 last cmd=0x12345678
92------------------------------------------------------------------------
93
94The first line is a warning, and this is usually relatively harmless.
95It means that the codec response isn't notified via an IRQ. The
96driver uses explicit polling method to read the response. It gives
97very slight CPU overhead, but you'd unlikely notice it.
98
99The second line is, however, a fatal error. If this happens, usually
100it means that something is really wrong. Most likely you are
101accessing a non-existing codec slot.
102
103Thus, if the second error message appears, try to narrow the probed
104codec slots via `probe_mask` option. It's a bitmask, and each bit
105corresponds to the codec slot. For example, to probe only the first
106slot, pass `probe_mask=1`. For the first and the third slots, pass
107`probe_mask=5` (where 5 = 1 | 4), and so on.
108
109Since 2.6.29 kernel, the driver has a more robust probing method, so
110this error might happen rarely, though.
111
112
113Interrupt Handling
114~~~~~~~~~~~~~~~~~~
115In rare but some cases, the interrupt isn't properly handled as
116default. You would notice this by the DMA transfer error reported by
117ALSA PCM core, for example. Using MSI might help in such a case.
118Pass `enable_msi=1` option for enabling MSI.
119
120
121HD-AUDIO CODEC
122--------------
123
124Model Option
125~~~~~~~~~~~~
126The most common problem regarding the HD-audio driver is the
127unsupported codec features or the mismatched device configuration.
128Most of codec-specific code has several preset models, either to
129override the BIOS setup or to provide more comprehensive features.
130
131The driver checks PCI SSID and looks through the static configuration
132table until any matching entry is found. If you have a new machine,
133you may see a message like below:
134------------------------------------------------------------------------
135 hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
136------------------------------------------------------------------------
137Even if you see such a message, DON'T PANIC. Take a deep breath and
138keep your towel. First of all, it's an informational message, no
139warning, no error. This means that the PCI SSID of your device isn't
140listed in the known preset model (white-)list. But, this doesn't mean
141that the driver is broken. Many codec-drivers provide the automatic
142configuration mechanism based on the BIOS setup.
143
144The HD-audio codec has usually "pin" widgets, and BIOS sets the default
145configuration of each pin, which indicates the location, the
146connection type, the jack color, etc. The HD-audio driver can guess
147the right connection judging from these default configuration values.
148However -- some codec-support codes, such as patch_analog.c, don't
149support the automatic probing (yet as of 2.6.28). And, BIOS is often,
150yes, pretty often broken. It sets up wrong values and screws up the
151driver.
152
153The preset model is provided basically to overcome such a situation.
154When the matching preset model is found in the white-list, the driver
155assumes the static configuration of that preset and builds the mixer
156elements and PCM streams based on the static information. Thus, if
157you have a newer machine with a slightly different PCI SSID from the
158existing one, you may have a good chance to re-use the same model.
159You can pass the `model` option to specify the preset model instead of
160PCI SSID look-up.
161
162What `model` option values are available depends on the codec chip.
163Check your codec chip from the codec proc file (see "Codec Proc-File"
164section below). It will show the vendor/product name of your codec
165chip. Then, see Documentation/sound/alsa/HD-Audio-Modelstxt file,
166the section of HD-audio driver. You can find a list of codecs
167and `model` options belonging to each codec. For example, for Realtek
168ALC262 codec chip, pass `model=ultra` for devices that are compatible
169with Samsung Q1 Ultra.
170
171Thus, the first thing you can do for any brand-new, unsupported and
172non-working HD-audio hardware is to check HD-audio codec and several
173different `model` option values. If you have a luck, some of them
174might suit with your device well.
175
176Some codecs such as ALC880 have a special model option `model=test`.
177This configures the driver to provide as many mixer controls as
178possible for every single pin feature except for the unsolicited
179events (and maybe some other specials). Adjust each mixer element and
180try the I/O in the way of trial-and-error until figuring out the whole
181I/O pin mappings.
182
183Note that `model=generic` has a special meaning. It means to use the
184generic parser regardless of the codec. Usually the codec-specific
185parser is much better than the generic parser (as now). Thus this
186option is more about the debugging purpose.
187
188
189Speaker and Headphone Output
190~~~~~~~~~~~~~~~~~~~~~~~~~~~~
191One of the most frequent (and obvious) bugs with HD-audio is the
192silent output from either or both of a built-in speaker and a
193headphone jack. In general, you should try a headphone output at
194first. A speaker output often requires more additional controls like
195the external amplifier bits. Thus a headphone output has a slightly
196better chance.
197
198Before making a bug report, double-check whether the mixer is set up
199correctly. The recent version of snd-hda-intel driver provides mostly
200"Master" volume control as well as "Front" volume (where Front
201indicates the front-channels). In addition, there can be individual
202"Headphone" and "Speaker" controls.
203
204Ditto for the speaker output. There can be "External Amplifier"
205switch on some codecs. Turn on this if present.
206
207Another related problem is the automatic mute of speaker output by
208headphone plugging. This feature is implemented in most cases, but
209not on every preset model or codec-support code.
210
211In anyway, try a different model option if you have such a problem.
212Some other models may match better and give you more matching
213functionality. If none of the available models works, send a bug
214report. See the bug report section for details.
215
216If you are masochistic enough to debug the driver problem, note the
217following:
218
219- The speaker (and the headphone, too) output often requires the
220 external amplifier. This can be set usually via EAPD verb or a
221 certain GPIO. If the codec pin supports EAPD, you have a better
222 chance via SET_EAPD_BTL verb (0x70c). On others, GPIO pin (mostly
223 it's either GPIO0 or GPIO1) may turn on/off EAPD.
224- Some Realtek codecs require special vendor-specific coefficients to
225 turn on the amplifier. See patch_realtek.c.
226- IDT codecs may have extra power-enable/disable controls on each
227 analog pin. See patch_sigmatel.c.
228- Very rare but some devices don't accept the pin-detection verb until
229 triggered. Issuing GET_PIN_SENSE verb (0xf09) may result in the
230 codec-communication stall. Some examples are found in
231 patch_realtek.c.
232
233
234Capture Problems
235~~~~~~~~~~~~~~~~
236The capture problems are often because of missing setups of mixers.
237Thus, before submitting a bug report, make sure that you set up the
238mixer correctly. For example, both "Capture Volume" and "Capture
239Switch" have to be set properly in addition to the right "Capture
240Source" or "Input Source" selection. Some devices have "Mic Boost"
241volume or switch.
242
243When the PCM device is opened via "default" PCM (without pulse-audio
244plugin), you'll likely have "Digital Capture Volume" control as well.
245This is provided for the extra gain/attenuation of the signal in
246software, especially for the inputs without the hardware volume
247control such as digital microphones. Unless really needed, this
248should be set to exactly 50%, corresponding to 0dB -- neither extra
249gain nor attenuation. When you use "hw" PCM, i.e., a raw access PCM,
250this control will have no influence, though.
251
252It's known that some codecs / devices have fairly bad analog circuits,
253and the recorded sound contains a certain DC-offset. This is no bug
254of the driver.
255
256Most of modern laptops have no analog CD-input connection. Thus, the
257recording from CD input won't work in many cases although the driver
258provides it as the capture source. Use CDDA instead.
259
260The automatic switching of the built-in and external mic per plugging
261is implemented on some codec models but not on every model. Partly
262because of my laziness but mostly lack of testers. Feel free to
263submit the improvement patch to the author.
264
265
266Direct Debugging
267~~~~~~~~~~~~~~~~
268If no model option gives you a better result, and you are a tough guy
269to fight against evil, try debugging via hitting the raw HD-audio
270codec verbs to the device. Some tools are available: hda-emu and
271hda-analyzer. The detailed description is found in the sections
272below. You'd need to enable hwdep for using these tools. See "Kernel
273Configuration" section.
274
275
276OTHER ISSUES
277------------
278
279Kernel Configuration
280~~~~~~~~~~~~~~~~~~~~
281In general, I recommend you to enable the sound debug option,
282`CONFIG_SND_DEBUG=y`, no matter whether you are debugging or not.
283This enables snd_printd() macro and others, and you'll get additional
284kernel messages at probing.
285
286In addition, you can enable `CONFIG_SND_DEBUG_VERBOSE=y`. But this
287will give you far more messages. Thus turn this on only when you are
288sure to want it.
289
290Don't forget to turn on the appropriate `CONFIG_SND_HDA_CODEC_*`
291options. Note that each of them corresponds to the codec chip, not
292the controller chip. Thus, even if lspci shows the Nvidia controller,
293you may need to choose the option for other vendors. If you are
294unsure, just select all yes.
295
296`CONFIG_SND_HDA_HWDEP` is a useful option for debugging the driver.
297When this is enabled, the driver creates hardware-dependent devices
298(one per each codec), and you have a raw access to the device via
299these device files. For example, `hwC0D2` will be created for the
300codec slot #2 of the first card (#0). For debug-tools such as
301hda-verb and hda-analyzer, the hwdep device has to be enabled.
302Thus, it'd be better to turn this on always.
303
304`CONFIG_SND_HDA_RECONFIG` is a new option, and this depends on the
305hwdep option above. When enabled, you'll have some sysfs files under
306the corresponding hwdep directory. See "HD-audio reconfiguration"
307section below.
308
309`CONFIG_SND_HDA_POWER_SAVE` option enables the power-saving feature.
310See "Power-saving" section below.
311
312
313Codec Proc-File
314~~~~~~~~~~~~~~~
315The codec proc-file is a treasure-chest for debugging HD-audio.
316It shows most of useful information of each codec widget.
317
318The proc file is located in /proc/asound/card*/codec#*, one file per
319each codec slot. You can know the codec vendor, product id and
320names, the type of each widget, capabilities and so on.
321This file, however, doesn't show the jack sensing state, so far. This
322is because the jack-sensing might be depending on the trigger state.
323
324This file will be picked up by the debug tools, and also it can be fed
325to the emulator as the primary codec information. See the debug tools
326section below.
327
328This proc file can be also used to check whether the generic parser is
329used. When the generic parser is used, the vendor/product ID name
330will appear as "Realtek ID 0262", instead of "Realtek ALC262".
331
332
333HD-Audio Reconfiguration
334~~~~~~~~~~~~~~~~~~~~~~~~
335This is an experimental feature to allow you re-configure the HD-audio
336codec dynamically without reloading the driver. The following sysfs
337files are available under each codec-hwdep device directory (e.g.
338/sys/class/sound/hwC0D0):
339
340vendor_id::
341 Shows the 32bit codec vendor-id hex number. You can change the
342 vendor-id value by writing to this file.
343subsystem_id::
344 Shows the 32bit codec subsystem-id hex number. You can change the
345 subsystem-id value by writing to this file.
346revision_id::
347 Shows the 32bit codec revision-id hex number. You can change the
348 revision-id value by writing to this file.
349afg::
350 Shows the AFG ID. This is read-only.
351mfg::
352 Shows the MFG ID. This is read-only.
353name::
354 Shows the codec name string. Can be changed by writing to this
355 file.
356modelname::
357 Shows the currently set `model` option. Can be changed by writing
358 to this file.
359init_verbs::
360 The extra verbs to execute at initialization. You can add a verb by
361 writing to this file. Pass tree numbers, nid, verb and parameter.
362hints::
363 Shows hint strings for codec parsers for any use. Right now it's
364 not used.
365reconfig::
366 Triggers the codec re-configuration. When any value is written to
367 this file, the driver re-initialize and parses the codec tree
368 again. All the changes done by the sysfs entries above are taken
369 into account.
370clear::
371 Resets the codec, removes the mixer elements and PCM stuff of the
372 specified codec, and clear all init verbs and hints.
373
374
375Power-Saving
376~~~~~~~~~~~~
377The power-saving is a kind of auto-suspend of the device. When the
378device is inactive for a certain time, the device is automatically
379turned off to save the power. The time to go down is specified via
380`power_save` module option, and this option can be changed dynamically
381via sysfs.
382
383The power-saving won't work when the analog loopback is enabled on
384some codecs. Make sure that you mute all unneeded signal routes when
385you want the power-saving.
386
387The power-saving feature might cause audible click noises at each
388power-down/up depending on the device. Some of them might be
389solvable, but some are hard, I'm afraid. Some distros such as
390openSUSE enables the power-saving feature automatically when the power
391cable is unplugged. Thus, if you hear noises, suspect first the
392power-saving. See /sys/module/snd_hda_intel/parameters/power_save to
393check the current value. If it's non-zero, the feature is turned on.
394
395
396Development Tree
397~~~~~~~~~~~~~~~~
398The latest development codes for HD-audio are found on sound git tree:
399
400- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git
401
402The master branch or for-next branches can be used as the main
403development branches in general while the HD-audio specific patches
404are committed in topic/hda branch.
405
406If you are using the latest Linus tree, it'd be better to pull the
407above GIT tree onto it. If you are using the older kernels, an easy
408way to try the latest ALSA code is to build from the snapshot
409tarball. There are daily tarballs and the latest snapshot tarball.
410All can be built just like normal alsa-driver release packages, that
411is, installed via the usual spells: configure, make and make
412install(-modules). See INSTALL in the package. The snapshot tarballs
413are found at:
414
415- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/snapshot/
416
417
418Sending a Bug Report
419~~~~~~~~~~~~~~~~~~~~
420If any model or module options don't work for your device, it's time
421to send a bug report to the developers. Give the following in your
422bug report:
423
424- Hardware vendor, product and model names
425- Kernel version (and ALSA-driver version if you built externally)
426- `alsa-info.sh` output; run with `--no-upload` option. See the
427 section below about alsa-info
428
429If it's a regression, at best, send alsa-info outputs of both working
430and non-working kernels. This is really helpful because we can
431compare the codec registers directly.
432
433Send a bug report either the followings:
434
435kernel-bugzilla::
436 http://bugme.linux-foundation.org/
437alsa-devel ML::
438 alsa-devel@alsa-project.org
439
440
441DEBUG TOOLS
442-----------
443
444This section describes some tools available for debugging HD-audio
445problems.
446
447alsa-info
448~~~~~~~~~
449The script `alsa-info.sh` is a very useful tool to gather the audio
450device information. You can fetch the latest version from:
451
452- http://www.alsa-project.org/alsa-info.sh
453
454Run this script as root, and it will gather the important information
455such as the module lists, module parameters, proc file contents
456including the codec proc files, mixer outputs and the control
457elements. As default, it will store the information onto a web server
458on alsa-project.org. But, if you send a bug report, it'd be better to
459run with `--no-upload` option, and attach the generated file.
460
461There are some other useful options. See `--help` option output for
462details.
463
464
465hda-verb
466~~~~~~~~
467hda-verb is a tiny program that allows you to access the HD-audio
468codec directly. You can execute a raw HD-audio codec verb with this.
469This program accesses the hwdep device, thus you need to enable the
470kernel config `CONFIG_SND_HDA_HWDEP=y` beforehand.
471
472The hda-verb program takes four arguments: the hwdep device file, the
473widget NID, the verb and the parameter. When you access to the codec
474on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first
475argument, typically. (However, the real path name depends on the
476system.)
477
478The second parameter is the widget number-id to access. The third
479parameter can be either a hex/digit number or a string corresponding
480to a verb. Similarly, the last parameter is the value to write, or
481can be a string for the parameter type.
482
483------------------------------------------------------------------------
484 % hda-verb /dev/snd/hwC0D0 0x12 0x701 2
485 nid = 0x12, verb = 0x701, param = 0x2
486 value = 0x0
487
488 % hda-verb /dev/snd/hwC0D0 0x0 PARAMETERS VENDOR_ID
489 nid = 0x0, verb = 0xf00, param = 0x0
490 value = 0x10ec0262
491
492 % hda-verb /dev/snd/hwC0D0 2 set_a 0xb080
493 nid = 0x2, verb = 0x300, param = 0xb080
494 value = 0x0
495------------------------------------------------------------------------
496
497Although you can issue any verbs with this program, the driver state
498won't be always updated. For example, the volume values are usually
499cached in the driver, and thus changing the widget amp value directly
500via hda-verb won't change the mixer value.
501
502The hda-verb program is found in the ftp directory:
503
504- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/misc/
505
506Also a git repository is available:
507
508- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-verb.git
509
510See README file in the tarball for more details about hda-verb
511program.
512
513
514hda-analyzer
515~~~~~~~~~~~~
516hda-analyzer provides a graphical interface to access the raw HD-audio
517control, based on pyGTK2 binding. It's a more powerful version of
518hda-verb. The program gives you an easy-to-use GUI stuff for showing
519the widget information and adjusting the amp values, as well as the
520proc-compatible output.
521
522The hda-analyzer is a part of alsa.git repository in
523alsa-project.org:
524
525- http://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer
526
527
528Codecgraph
529~~~~~~~~~~
530Codecgraph is a utility program to generate a graph and visualizes the
531codec-node connection of a codec chip. It's especially useful when
532you analyze or debug a codec without a proper datasheet. The program
533parses the given codec proc file and converts to SVG via graphiz
534program.
535
536The tarball and GIT trees are found in the web page at:
537
538- http://helllabs.org/codecgraph/
539
540
541hda-emu
542~~~~~~~
543hda-emu is an HD-audio emulator. The main purpose of this program is
544to debug an HD-audio codec without the real hardware. Thus, it
545doesn't emulate the behavior with the real audio I/O, but it just
546dumps the codec register changes and the ALSA-driver internal changes
547at probing and operating the HD-audio driver.
548
549The program requires a codec proc-file to simulate. Get a proc file
550for the target codec beforehand, or pick up an example codec from the
551codec proc collections in the tarball. Then, run the program with the
552proc file, and the hda-emu program will start parsing the codec file
553and simulates the HD-audio driver:
554
555------------------------------------------------------------------------
556 % hda-emu codecs/stac9200-dell-d820-laptop
557 # Parsing..
558 hda_codec: Unknown model for STAC9200, using BIOS defaults
559 hda_codec: pin nid 08 bios pin config 40c003fa
560 ....
561------------------------------------------------------------------------
562
563The program gives you only a very dumb command-line interface. You
564can get a proc-file dump at the current state, get a list of control
565(mixer) elements, set/get the control element value, simulate the PCM
566operation, the jack plugging simulation, etc.
567
568The package is found in:
569
570- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/misc/
571
572A git repository is available:
573
574- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-emu.git
575
576See README file in the tarball for more details about hda-emu
577program.