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Based on kernel version 2.6.33. Page generated on 2010-02-24 15:37 EST.

1	MORE NOTES ON HD-AUDIO DRIVER
2	=============================
3						Takashi Iwai <tiwai[AT]suse[DOT]de>
4	
5	
6	GENERAL
7	-------
8	
9	HD-audio is the new standard on-board audio component on modern PCs
10	after AC97.  Although Linux has been supporting HD-audio since long
11	time ago, there are often problems with new machines.  A part of the
12	problem is broken BIOS, and the rest is the driver implementation.
13	This document explains the brief trouble-shooting and debugging
14	methods for the	HD-audio hardware.
15	
16	The HD-audio component consists of two parts: the controller chip and 
17	the codec chips on the HD-audio bus.  Linux provides a single driver
18	for all controllers, snd-hda-intel.  Although the driver name contains
19	a word of a well-known hardware vendor, it's not specific to it but for
20	all controller chips by other companies.  Since the HD-audio
21	controllers are supposed to be compatible, the single snd-hda-driver
22	should work in most cases.  But, not surprisingly, there are known
23	bugs and issues specific to each controller type.  The snd-hda-intel
24	driver has a bunch of workarounds for these as described below.
25	
26	A controller may have multiple codecs.  Usually you have one audio
27	codec and optionally one modem codec.  In theory, there might be
28	multiple audio codecs, e.g. for analog and digital outputs, and the
29	driver might not work properly because of conflict of mixer elements.
30	This should be fixed in future if such hardware really exists.
31	
32	The snd-hda-intel driver has several different codec parsers depending
33	on the codec.  It has a generic parser as a fallback, but this
34	functionality is fairly limited until now.  Instead of the generic
35	parser, usually the codec-specific parser (coded in patch_*.c) is used
36	for the codec-specific implementations.  The details about the
37	codec-specific problems are explained in the later sections.
38	
39	If you are interested in the deep debugging of HD-audio, read the
40	HD-audio specification at first.  The specification is found on
41	Intel's web page, for example:
42	
43	- http://www.intel.com/standards/hdaudio/
44	
45	
46	HD-AUDIO CONTROLLER
47	-------------------
48	
49	DMA-Position Problem
50	~~~~~~~~~~~~~~~~~~~~
51	The most common problem of the controller is the inaccurate DMA
52	pointer reporting.  The DMA pointer for playback and capture can be
53	read in two ways, either via a LPIB register or via a position-buffer
54	map.  As default the driver tries to read from the io-mapped
55	position-buffer, and falls back to LPIB if the position-buffer appears
56	dead.  However, this detection isn't perfect on some devices.  In such
57	a 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
61	value, the automatic check and fallback to LPIB as described in the
62	above.  If you get a problem of repeated sounds, this option might
63	help.
64	
65	In addition to that, every controller is known to be broken regarding
66	the wake-up timing.  It wakes up a few samples before actually
67	processing the data on the buffer.  This caused a lot of problems, for
68	example, with ALSA dmix or JACK.  Since 2.6.27 kernel, the driver puts
69	an artificial delay to the wake up timing.  This delay is controlled
70	via `bdl_pos_adj` option. 
71	
72	When `bdl_pos_adj` is a negative value (as default), it's assigned to
73	an appropriate value depending on the controller chip.  For Intel
74	chips, it'd be 1 while it'd be 32 for others.  Usually this works.
75	Only in case it doesn't work and you get warning messages, you should
76	change this parameter to other values.
77	
78	
79	Codec-Probing Problem
80	~~~~~~~~~~~~~~~~~~~~~
81	A less often but a more severe problem is the codec probing.  When
82	BIOS reports the available codec slots wrongly, the driver gets
83	confused and tries to access the non-existing codec slot.  This often
84	results in the total screw-up, and destructs the further communication
85	with the codec chips.  The symptom appears usually as error messages
86	like:
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	
94	The first line is a warning, and this is usually relatively harmless.
95	It means that the codec response isn't notified via an IRQ.  The
96	driver uses explicit polling method to read the response.  It gives
97	very slight CPU overhead, but you'd unlikely notice it.
98	
99	The second line is, however, a fatal error.  If this happens, usually
100	it means that something is really wrong.  Most likely you are
101	accessing a non-existing codec slot.
102	
103	Thus, if the second error message appears, try to narrow the probed
104	codec slots via `probe_mask` option.  It's a bitmask, and each bit
105	corresponds to the codec slot.  For example, to probe only the first
106	slot, pass `probe_mask=1`.  For the first and the third slots, pass
107	`probe_mask=5` (where 5 = 1 | 4), and so on.
108	
109	Since 2.6.29 kernel, the driver has a more robust probing method, so
110	this error might happen rarely, though.
111	
112	On a machine with a broken BIOS, sometimes you need to force the
113	driver to probe the codec slots the hardware doesn't report for use.
114	In such a case, turn the bit 8 (0x100) of `probe_mask` option on.
115	Then the rest 8 bits are passed as the codec slots to probe
116	unconditionally.  For example, `probe_mask=0x103` will force to probe
117	the codec slots 0 and 1 no matter what the hardware reports.
118	
119	
120	Interrupt Handling
121	~~~~~~~~~~~~~~~~~~
122	In rare but some cases, the interrupt isn't properly handled as
123	default.  You would notice this by the DMA transfer error reported by
124	ALSA PCM core, for example.  Using MSI might help in such a case.
125	Pass `enable_msi=1` option for enabling MSI.
126	
127	
128	HD-AUDIO CODEC
129	--------------
130	
131	Model Option
132	~~~~~~~~~~~~
133	The most common problem regarding the HD-audio driver is the
134	unsupported codec features or the mismatched device configuration.
135	Most of codec-specific code has several preset models, either to
136	override the BIOS setup or to provide more comprehensive features.
137	
138	The driver checks PCI SSID and looks through the static configuration
139	table until any matching entry is found.  If you have a new machine,
140	you may see a message like below:
141	------------------------------------------------------------------------
142	    hda_codec: ALC880: BIOS auto-probing.
143	------------------------------------------------------------------------
144	Meanwhile, in the earlier versions, you would see a message like:
145	------------------------------------------------------------------------
146	    hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
147	------------------------------------------------------------------------
148	Even if you see such a message, DON'T PANIC.  Take a deep breath and
149	keep your towel.  First of all, it's an informational message, no
150	warning, no error.  This means that the PCI SSID of your device isn't
151	listed in the known preset model (white-)list.  But, this doesn't mean
152	that the driver is broken.  Many codec-drivers provide the automatic
153	configuration mechanism based on the BIOS setup.
154	
155	The HD-audio codec has usually "pin" widgets, and BIOS sets the default
156	configuration of each pin, which indicates the location, the
157	connection type, the jack color, etc.  The HD-audio driver can guess
158	the right connection judging from these default configuration values.
159	However -- some codec-support codes, such as patch_analog.c, don't
160	support the automatic probing (yet as of 2.6.28).  And, BIOS is often,
161	yes, pretty often broken.  It sets up wrong values and screws up the
162	driver.
163	
164	The preset model is provided basically to overcome such a situation.
165	When the matching preset model is found in the white-list, the driver
166	assumes the static configuration of that preset and builds the mixer
167	elements and PCM streams based on the static information.  Thus, if
168	you have a newer machine with a slightly different PCI SSID from the
169	existing one, you may have a good chance to re-use the same model.
170	You can pass the `model` option to specify the preset model instead of
171	PCI SSID look-up.
172	
173	What `model` option values are available depends on the codec chip.
174	Check your codec chip from the codec proc file (see "Codec Proc-File"
175	section below).  It will show the vendor/product name of your codec
176	chip.  Then, see Documentation/sound/alsa/HD-Audio-Models.txt file,
177	the section of HD-audio driver.  You can find a list of codecs
178	and `model` options belonging to each codec.  For example, for Realtek
179	ALC262 codec chip, pass `model=ultra` for devices that are compatible
180	with Samsung Q1 Ultra.
181	
182	Thus, the first thing you can do for any brand-new, unsupported and
183	non-working HD-audio hardware is to check HD-audio codec and several
184	different `model` option values.  If you have any luck, some of them
185	might suit with your device well.
186	
187	Some codecs such as ALC880 have a special model option `model=test`.
188	This configures the driver to provide as many mixer controls as
189	possible for every single pin feature except for the unsolicited
190	events (and maybe some other specials).  Adjust each mixer element and
191	try the I/O in the way of trial-and-error until figuring out the whole
192	I/O pin mappings.
193	
194	Note that `model=generic` has a special meaning.  It means to use the
195	generic parser regardless of the codec.  Usually the codec-specific
196	parser is much better than the generic parser (as now).  Thus this
197	option is more about the debugging purpose.
198	
199	
200	Speaker and Headphone Output
201	~~~~~~~~~~~~~~~~~~~~~~~~~~~~
202	One of the most frequent (and obvious) bugs with HD-audio is the
203	silent output from either or both of a built-in speaker and a
204	headphone jack.  In general, you should try a headphone output at
205	first.  A speaker output often requires more additional controls like
206	the external amplifier bits.  Thus a headphone output has a slightly
207	better chance.
208	
209	Before making a bug report, double-check whether the mixer is set up
210	correctly.  The recent version of snd-hda-intel driver provides mostly
211	"Master" volume control as well as "Front" volume (where Front
212	indicates the front-channels).  In addition, there can be individual
213	"Headphone" and "Speaker" controls.
214	
215	Ditto for the speaker output.  There can be "External Amplifier"
216	switch on some codecs.  Turn on this if present.
217	
218	Another related problem is the automatic mute of speaker output by
219	headphone plugging.  This feature is implemented in most cases, but
220	not on every preset model or codec-support code.
221	
222	In anyway, try a different model option if you have such a problem.
223	Some other models may match better and give you more matching
224	functionality.  If none of the available models works, send a bug
225	report.  See the bug report section for details.
226	
227	If you are masochistic enough to debug the driver problem, note the
228	following:
229	
230	- The speaker (and the headphone, too) output often requires the
231	  external amplifier.  This can be set usually via EAPD verb or a
232	  certain GPIO.  If the codec pin supports EAPD, you have a better
233	  chance via SET_EAPD_BTL verb (0x70c).  On others, GPIO pin (mostly
234	  it's either GPIO0 or GPIO1) may turn on/off EAPD.
235	- Some Realtek codecs require special vendor-specific coefficients to
236	  turn on the amplifier.  See patch_realtek.c.
237	- IDT codecs may have extra power-enable/disable controls on each
238	  analog pin.  See patch_sigmatel.c.
239	- Very rare but some devices don't accept the pin-detection verb until
240	  triggered.  Issuing GET_PIN_SENSE verb (0xf09) may result in the
241	  codec-communication stall.  Some examples are found in
242	  patch_realtek.c.
243	
244	
245	Capture Problems
246	~~~~~~~~~~~~~~~~
247	The capture problems are often because of missing setups of mixers.
248	Thus, before submitting a bug report, make sure that you set up the
249	mixer correctly.  For example, both "Capture Volume" and "Capture
250	Switch" have to be set properly in addition to the right "Capture
251	Source" or "Input Source" selection.  Some devices have "Mic Boost"
252	volume or switch.
253	
254	When the PCM device is opened via "default" PCM (without pulse-audio
255	plugin), you'll likely have "Digital Capture Volume" control as well.
256	This is provided for the extra gain/attenuation of the signal in
257	software, especially for the inputs without the hardware volume
258	control such as digital microphones.  Unless really needed, this
259	should be set to exactly 50%, corresponding to 0dB -- neither extra
260	gain nor attenuation.  When you use "hw" PCM, i.e., a raw access PCM,
261	this control will have no influence, though.
262	
263	It's known that some codecs / devices have fairly bad analog circuits,
264	and the recorded sound contains a certain DC-offset.  This is no bug
265	of the driver.
266	
267	Most of modern laptops have no analog CD-input connection.  Thus, the
268	recording from CD input won't work in many cases although the driver
269	provides it as the capture source.  Use CDDA instead.
270	
271	The automatic switching of the built-in and external mic per plugging
272	is implemented on some codec models but not on every model.  Partly
273	because of my laziness but mostly lack of testers.  Feel free to
274	submit the improvement patch to the author.
275	
276	
277	Direct Debugging
278	~~~~~~~~~~~~~~~~
279	If no model option gives you a better result, and you are a tough guy
280	to fight against evil, try debugging via hitting the raw HD-audio
281	codec verbs to the device.  Some tools are available: hda-emu and
282	hda-analyzer.  The detailed description is found in the sections
283	below.  You'd need to enable hwdep for using these tools.  See "Kernel
284	Configuration" section.
285	
286	
287	OTHER ISSUES
288	------------
289	
290	Kernel Configuration
291	~~~~~~~~~~~~~~~~~~~~
292	In general, I recommend you to enable the sound debug option,
293	`CONFIG_SND_DEBUG=y`, no matter whether you are debugging or not.
294	This enables snd_printd() macro and others, and you'll get additional
295	kernel messages at probing.
296	
297	In addition, you can enable `CONFIG_SND_DEBUG_VERBOSE=y`.  But this
298	will give you far more messages.  Thus turn this on only when you are
299	sure to want it.
300	
301	Don't forget to turn on the appropriate `CONFIG_SND_HDA_CODEC_*`
302	options.  Note that each of them corresponds to the codec chip, not
303	the controller chip.  Thus, even if lspci shows the Nvidia controller,
304	you may need to choose the option for other vendors.  If you are
305	unsure, just select all yes.
306	
307	`CONFIG_SND_HDA_HWDEP` is a useful option for debugging the driver.
308	When this is enabled, the driver creates hardware-dependent devices
309	(one per each codec), and you have a raw access to the device via
310	these device files.  For example, `hwC0D2` will be created for the
311	codec slot #2 of the first card (#0).  For debug-tools such as
312	hda-verb and hda-analyzer, the hwdep device has to be enabled.
313	Thus, it'd be better to turn this on always.
314	
315	`CONFIG_SND_HDA_RECONFIG` is a new option, and this depends on the
316	hwdep option above.  When enabled, you'll have some sysfs files under
317	the corresponding hwdep directory.  See "HD-audio reconfiguration"
318	section below.
319	
320	`CONFIG_SND_HDA_POWER_SAVE` option enables the power-saving feature.
321	See "Power-saving" section below.
322	
323	
324	Codec Proc-File
325	~~~~~~~~~~~~~~~
326	The codec proc-file is a treasure-chest for debugging HD-audio.
327	It shows most of useful information of each codec widget.
328	
329	The proc file is located in /proc/asound/card*/codec#*, one file per
330	each codec slot.  You can know the codec vendor, product id and
331	names, the type of each widget, capabilities and so on.
332	This file, however, doesn't show the jack sensing state, so far.  This
333	is because the jack-sensing might be depending on the trigger state.
334	
335	This file will be picked up by the debug tools, and also it can be fed
336	to the emulator as the primary codec information.  See the debug tools
337	section below.
338	
339	This proc file can be also used to check whether the generic parser is
340	used.  When the generic parser is used, the vendor/product ID name
341	will appear as "Realtek ID 0262", instead of "Realtek ALC262".
342	
343	
344	HD-Audio Reconfiguration
345	~~~~~~~~~~~~~~~~~~~~~~~~
346	This is an experimental feature to allow you re-configure the HD-audio
347	codec dynamically without reloading the driver.  The following sysfs
348	files are available under each codec-hwdep device directory (e.g. 
349	/sys/class/sound/hwC0D0):
350	
351	vendor_id::
352	  Shows the 32bit codec vendor-id hex number.  You can change the
353	  vendor-id value by writing to this file.
354	subsystem_id::
355	  Shows the 32bit codec subsystem-id hex number.  You can change the
356	  subsystem-id value by writing to this file.
357	revision_id::
358	  Shows the 32bit codec revision-id hex number.  You can change the
359	  revision-id value by writing to this file.
360	afg::
361	  Shows the AFG ID.  This is read-only.
362	mfg::
363	  Shows the MFG ID.  This is read-only.
364	name::
365	  Shows the codec name string.  Can be changed by writing to this
366	  file.
367	modelname::
368	  Shows the currently set `model` option.  Can be changed by writing
369	  to this file.
370	init_verbs::
371	  The extra verbs to execute at initialization.  You can add a verb by
372	  writing to this file.  Pass three numbers: nid, verb and parameter
373	  (separated with a space).
374	hints::
375	  Shows / stores hint strings for codec parsers for any use.
376	  Its format is `key = value`.  For example, passing `hp_detect = yes`
377	  to IDT/STAC codec parser will result in the disablement of the
378	  headphone detection.
379	init_pin_configs::
380	  Shows the initial pin default config values set by BIOS.
381	driver_pin_configs::
382	  Shows the pin default values set by the codec parser explicitly.
383	  This doesn't show all pin values but only the changed values by
384	  the parser.  That is, if the parser doesn't change the pin default
385	  config values by itself, this will contain nothing.
386	user_pin_configs::
387	  Shows the pin default config values to override the BIOS setup.
388	  Writing this (with two numbers, NID and value) appends the new
389	  value.  The given will be used instead of the initial BIOS value at
390	  the next reconfiguration time.  Note that this config will override
391	  even the driver pin configs, too.
392	reconfig::
393	  Triggers the codec re-configuration.  When any value is written to
394	  this file, the driver re-initialize and parses the codec tree
395	  again.  All the changes done by the sysfs entries above are taken
396	  into account.
397	clear::
398	  Resets the codec, removes the mixer elements and PCM stuff of the
399	  specified codec, and clear all init verbs and hints.
400	
401	For example, when you want to change the pin default configuration
402	value of the pin widget 0x14 to 0x9993013f, and let the driver
403	re-configure based on that state, run like below:
404	------------------------------------------------------------------------
405	  # echo 0x14 0x9993013f > /sys/class/sound/hwC0D0/user_pin_configs
406	  # echo 1 > /sys/class/sound/hwC0D0/reconfig  
407	------------------------------------------------------------------------
408	
409	
410	Early Patching
411	~~~~~~~~~~~~~~
412	When CONFIG_SND_HDA_PATCH_LOADER=y is set, you can pass a "patch" as a
413	firmware file for modifying the HD-audio setup before initializing the
414	codec.  This can work basically like the reconfiguration via sysfs in
415	the above, but it does it before the first codec configuration.
416	
417	A patch file is a plain text file which looks like below:
418	
419	------------------------------------------------------------------------
420	  [codec]
421	  0x12345678 0xabcd1234 2
422	
423	  [model]
424	  auto
425	
426	  [pincfg]
427	  0x12 0x411111f0
428	
429	  [verb]
430	  0x20 0x500 0x03
431	  0x20 0x400 0xff
432	
433	  [hint]
434	  hp_detect = yes
435	------------------------------------------------------------------------
436	
437	The file needs to have a line `[codec]`.  The next line should contain
438	three numbers indicating the codec vendor-id (0x12345678 in the
439	example), the codec subsystem-id (0xabcd1234) and the address (2) of
440	the codec.  The rest patch entries are applied to this specified codec
441	until another codec entry is given.
442	
443	The `[model]` line allows to change the model name of the each codec.
444	In the example above, it will be changed to model=auto.
445	Note that this overrides the module option.
446	
447	After the `[pincfg]` line, the contents are parsed as the initial
448	default pin-configurations just like `user_pin_configs` sysfs above.
449	The values can be shown in user_pin_configs sysfs file, too.
450	
451	Similarly, the lines after `[verb]` are parsed as `init_verbs`
452	sysfs entries, and the lines after `[hint]` are parsed as `hints`
453	sysfs entries, respectively.
454	
455	The hd-audio driver reads the file via request_firmware().  Thus,
456	a patch file has to be located on the appropriate firmware path,
457	typically, /lib/firmware.  For example, when you pass the option
458	`patch=hda-init.fw`, the file /lib/firmware/hda-init-fw must be
459	present.
460	
461	The patch module option is specific to each card instance, and you
462	need to give one file name for each instance, separated by commas.
463	For example, if you have two cards, one for an on-board analog and one 
464	for an HDMI video board, you may pass patch option like below:
465	------------------------------------------------------------------------
466	    options snd-hda-intel patch=on-board-patch,hdmi-patch
467	------------------------------------------------------------------------
468	
469	
470	Power-Saving
471	~~~~~~~~~~~~
472	The power-saving is a kind of auto-suspend of the device.  When the
473	device is inactive for a certain time, the device is automatically
474	turned off to save the power.  The time to go down is specified via
475	`power_save` module option, and this option can be changed dynamically
476	via sysfs.
477	
478	The power-saving won't work when the analog loopback is enabled on
479	some codecs.  Make sure that you mute all unneeded signal routes when
480	you want the power-saving.
481	
482	The power-saving feature might cause audible click noises at each
483	power-down/up depending on the device.  Some of them might be
484	solvable, but some are hard, I'm afraid.  Some distros such as
485	openSUSE enables the power-saving feature automatically when the power
486	cable is unplugged.  Thus, if you hear noises, suspect first the
487	power-saving.  See /sys/module/snd_hda_intel/parameters/power_save to
488	check the current value.  If it's non-zero, the feature is turned on.
489	
490	
491	Development Tree
492	~~~~~~~~~~~~~~~~
493	The latest development codes for HD-audio are found on sound git tree:
494	
495	- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git
496	
497	The master branch or for-next branches can be used as the main
498	development branches in general while the HD-audio specific patches
499	are committed in topic/hda branch.
500	
501	If you are using the latest Linus tree, it'd be better to pull the
502	above GIT tree onto it.  If you are using the older kernels, an easy
503	way to try the latest ALSA code is to build from the snapshot
504	tarball.  There are daily tarballs and the latest snapshot tarball.
505	All can be built just like normal alsa-driver release packages, that
506	is, installed via the usual spells: configure, make and make
507	install(-modules).  See INSTALL in the package.  The snapshot tarballs
508	are found at:
509	
510	- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/snapshot/
511	
512	
513	Sending a Bug Report
514	~~~~~~~~~~~~~~~~~~~~
515	If any model or module options don't work for your device, it's time
516	to send a bug report to the developers.  Give the following in your
517	bug report:
518	
519	- Hardware vendor, product and model names
520	- Kernel version (and ALSA-driver version if you built externally)
521	- `alsa-info.sh` output; run with `--no-upload` option.  See the
522	  section below about alsa-info
523	
524	If it's a regression, at best, send alsa-info outputs of both working
525	and non-working kernels.  This is really helpful because we can
526	compare the codec registers directly.
527	
528	Send a bug report either the followings:
529	
530	kernel-bugzilla::
531	  http://bugme.linux-foundation.org/
532	alsa-devel ML::
533	  alsa-devel[AT]alsa-project[DOT]org
534	
535	
536	DEBUG TOOLS
537	-----------
538	
539	This section describes some tools available for debugging HD-audio
540	problems.
541	
542	alsa-info
543	~~~~~~~~~
544	The script `alsa-info.sh` is a very useful tool to gather the audio
545	device information.  You can fetch the latest version from:
546	
547	- http://www.alsa-project.org/alsa-info.sh
548	
549	Run this script as root, and it will gather the important information
550	such as the module lists, module parameters, proc file contents
551	including the codec proc files, mixer outputs and the control
552	elements.  As default, it will store the information onto a web server
553	on alsa-project.org.  But, if you send a bug report, it'd be better to
554	run with `--no-upload` option, and attach the generated file.
555	
556	There are some other useful options.  See `--help` option output for
557	details.
558	
559	When a probe error occurs or when the driver obviously assigns a
560	mismatched model, it'd be helpful to load the driver with
561	`probe_only=1` option (at best after the cold reboot) and run
562	alsa-info at this state.  With this option, the driver won't configure
563	the mixer and PCM but just tries to probe the codec slot.  After
564	probing, the proc file is available, so you can get the raw codec
565	information before modified by the driver.  Of course, the driver
566	isn't usable with `probe_only=1`.  But you can continue the
567	configuration via hwdep sysfs file if hda-reconfig option is enabled.
568	
569	
570	hda-verb
571	~~~~~~~~
572	hda-verb is a tiny program that allows you to access the HD-audio
573	codec directly.  You can execute a raw HD-audio codec verb with this.
574	This program accesses the hwdep device, thus you need to enable the
575	kernel config `CONFIG_SND_HDA_HWDEP=y` beforehand.
576	
577	The hda-verb program takes four arguments: the hwdep device file, the
578	widget NID, the verb and the parameter.  When you access to the codec
579	on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first
580	argument, typically.  (However, the real path name depends on the
581	system.)
582	
583	The second parameter is the widget number-id to access.  The third
584	parameter can be either a hex/digit number or a string corresponding
585	to a verb.  Similarly, the last parameter is the value to write, or
586	can be a string for the parameter type.
587	
588	------------------------------------------------------------------------
589	  % hda-verb /dev/snd/hwC0D0 0x12 0x701 2
590	  nid = 0x12, verb = 0x701, param = 0x2
591	  value = 0x0
592	
593	  % hda-verb /dev/snd/hwC0D0 0x0 PARAMETERS VENDOR_ID
594	  nid = 0x0, verb = 0xf00, param = 0x0
595	  value = 0x10ec0262
596	
597	  % hda-verb /dev/snd/hwC0D0 2 set_a 0xb080
598	  nid = 0x2, verb = 0x300, param = 0xb080
599	  value = 0x0
600	------------------------------------------------------------------------
601	
602	Although you can issue any verbs with this program, the driver state
603	won't be always updated.  For example, the volume values are usually
604	cached in the driver, and thus changing the widget amp value directly
605	via hda-verb won't change the mixer value.
606	
607	The hda-verb program is found in the ftp directory:
608	
609	- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/misc/
610	
611	Also a git repository is available:
612	
613	- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-verb.git
614	
615	See README file in the tarball for more details about hda-verb
616	program.
617	
618	
619	hda-analyzer
620	~~~~~~~~~~~~
621	hda-analyzer provides a graphical interface to access the raw HD-audio
622	control, based on pyGTK2 binding.  It's a more powerful version of
623	hda-verb.  The program gives you an easy-to-use GUI stuff for showing
624	the widget information and adjusting the amp values, as well as the
625	proc-compatible output.
626	
627	The hda-analyzer:
628	
629	- http://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer
630	
631	is a part of alsa.git repository in alsa-project.org:
632	
633	- git://git.alsa-project.org/alsa.git
634	
635	Codecgraph
636	~~~~~~~~~~
637	Codecgraph is a utility program to generate a graph and visualizes the
638	codec-node connection of a codec chip.  It's especially useful when
639	you analyze or debug a codec without a proper datasheet.  The program
640	parses the given codec proc file and converts to SVG via graphiz
641	program.
642	
643	The tarball and GIT trees are found in the web page at:
644	
645	- http://helllabs.org/codecgraph/
646	
647	
648	hda-emu
649	~~~~~~~
650	hda-emu is an HD-audio emulator.  The main purpose of this program is
651	to debug an HD-audio codec without the real hardware.  Thus, it
652	doesn't emulate the behavior with the real audio I/O, but it just
653	dumps the codec register changes and the ALSA-driver internal changes
654	at probing and operating the HD-audio driver.
655	
656	The program requires a codec proc-file to simulate.  Get a proc file
657	for the target codec beforehand, or pick up an example codec from the
658	codec proc collections in the tarball.  Then, run the program with the
659	proc file, and the hda-emu program will start parsing the codec file
660	and simulates the HD-audio driver:
661	
662	------------------------------------------------------------------------
663	  % hda-emu codecs/stac9200-dell-d820-laptop
664	  # Parsing..
665	  hda_codec: Unknown model for STAC9200, using BIOS defaults
666	  hda_codec: pin nid 08 bios pin config 40c003fa
667	  ....
668	------------------------------------------------------------------------
669	
670	The program gives you only a very dumb command-line interface.  You
671	can get a proc-file dump at the current state, get a list of control
672	(mixer) elements, set/get the control element value, simulate the PCM
673	operation, the jack plugging simulation, etc.
674	
675	The package is found in:
676	
677	- ftp://ftp.kernel.org/pub/linux/kernel/people/tiwai/misc/
678	
679	A git repository is available:
680	
681	- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-emu.git
682	
683	See README file in the tarball for more details about hda-emu
684	program.
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