1=============================
2More Notes on HD-Audio Driver
3=============================
4
5Takashi Iwai <tiwai@suse.de>
6
7
8General
9=======
10
11HD-audio is the new standard on-board audio component on modern PCs
12after AC97.  Although Linux has been supporting HD-audio since long
13time ago, there are often problems with new machines.  A part of the
14problem is broken BIOS, and the rest is the driver implementation.
15This document explains the brief trouble-shooting and debugging
16methods for the	HD-audio hardware.
17
18The HD-audio component consists of two parts: the controller chip and
19the codec chips on the HD-audio bus.  Linux provides a single driver
20for all controllers, snd-hda-intel.  Although the driver name contains
21a word of a well-known hardware vendor, it's not specific to it but for
22all controller chips by other companies.  Since the HD-audio
23controllers are supposed to be compatible, the single snd-hda-driver
24should work in most cases.  But, not surprisingly, there are known
25bugs and issues specific to each controller type.  The snd-hda-intel
26driver has a bunch of workarounds for these as described below.
27
28A controller may have multiple codecs.  Usually you have one audio
29codec and optionally one modem codec.  In theory, there might be
30multiple audio codecs, e.g. for analog and digital outputs, and the
31driver might not work properly because of conflict of mixer elements.
32This should be fixed in future if such hardware really exists.
33
34The snd-hda-intel driver has several different codec parsers depending
35on the codec.  It has a generic parser as a fallback, but this
36functionality is fairly limited until now.  Instead of the generic
37parser, usually the codec-specific parser (coded in patch_*.c) is used
38for the codec-specific implementations.  The details about the
39codec-specific problems are explained in the later sections.
40
41If you are interested in the deep debugging of HD-audio, read the
42HD-audio specification at first.  The specification is found on
43Intel's web page, for example:
44
45* https://www.intel.com/standards/hdaudio/
46
47
48HD-Audio Controller
49===================
50
51DMA-Position Problem
52--------------------
53The most common problem of the controller is the inaccurate DMA
54pointer reporting.  The DMA pointer for playback and capture can be
55read in two ways, either via a LPIB register or via a position-buffer
56map.  As default the driver tries to read from the io-mapped
57position-buffer, and falls back to LPIB if the position-buffer appears
58dead.  However, this detection isn't perfect on some devices.  In such
59a case, you can change the default method via ``position_fix`` option.
60
61``position_fix=1`` means to use LPIB method explicitly.
62``position_fix=2`` means to use the position-buffer.
63``position_fix=3`` means to use a combination of both methods, needed
64for some VIA controllers.  The capture stream position is corrected
65by comparing both LPIB and position-buffer values.
66``position_fix=4`` is another combination available for all controllers,
67and uses LPIB for the playback and the position-buffer for the capture
68streams.
69``position_fix=5`` is specific to Intel platforms, so far, for Skylake
70and onward.  It applies the delay calculation for the precise position
71reporting.
72``position_fix=6`` is to correct the position with the fixed FIFO
73size, mainly targeted for the recent AMD controllers.
740 is the default value for all other
75controllers, the automatic check and fallback to LPIB as described in
76the above.  If you get a problem of repeated sounds, this option might
77help.
78
79In addition to that, every controller is known to be broken regarding
80the wake-up timing.  It wakes up a few samples before actually
81processing the data on the buffer.  This caused a lot of problems, for
82example, with ALSA dmix or JACK.  Since 2.6.27 kernel, the driver puts
83an artificial delay to the wake up timing.  This delay is controlled
84via ``bdl_pos_adj`` option.
85
86When ``bdl_pos_adj`` is a negative value (as default), it's assigned to
87an appropriate value depending on the controller chip.  For Intel
88chips, it'd be 1 while it'd be 32 for others.  Usually this works.
89Only in case it doesn't work and you get warning messages, you should
90change this parameter to other values.
91
92
93Codec-Probing Problem
94---------------------
95A less often but a more severe problem is the codec probing.  When
96BIOS reports the available codec slots wrongly, the driver gets
97confused and tries to access the non-existing codec slot.  This often
98results in the total screw-up, and destructs the further communication
99with the codec chips.  The symptom appears usually as error messages
100like:
101::
102
103    hda_intel: azx_get_response timeout, switching to polling mode:
104          last cmd=0x12345678
105    hda_intel: azx_get_response timeout, switching to single_cmd mode:
106          last cmd=0x12345678
107
108The first line is a warning, and this is usually relatively harmless.
109It means that the codec response isn't notified via an IRQ.  The
110driver uses explicit polling method to read the response.  It gives
111very slight CPU overhead, but you'd unlikely notice it.
112
113The second line is, however, a fatal error.  If this happens, usually
114it means that something is really wrong.  Most likely you are
115accessing a non-existing codec slot.
116
117Thus, if the second error message appears, try to narrow the probed
118codec slots via ``probe_mask`` option.  It's a bitmask, and each bit
119corresponds to the codec slot.  For example, to probe only the first
120slot, pass ``probe_mask=1``.  For the first and the third slots, pass
121``probe_mask=5`` (where 5 = 1 | 4), and so on.
122
123Since 2.6.29 kernel, the driver has a more robust probing method, so
124this error might happen rarely, though.
125
126On a machine with a broken BIOS, sometimes you need to force the
127driver to probe the codec slots the hardware doesn't report for use.
128In such a case, turn the bit 8 (0x100) of ``probe_mask`` option on.
129Then the rest 8 bits are passed as the codec slots to probe
130unconditionally.  For example, ``probe_mask=0x103`` will force to probe
131the codec slots 0 and 1 no matter what the hardware reports.
132
133
134Interrupt Handling
135------------------
136HD-audio driver uses MSI as default (if available) since 2.6.33
137kernel as MSI works better on some machines, and in general, it's
138better for performance.  However, Nvidia controllers showed bad
139regressions with MSI (especially in a combination with AMD chipset),
140thus we disabled MSI for them.
141
142There seem also still other devices that don't work with MSI.  If you
143see a regression wrt the sound quality (stuttering, etc) or a lock-up
144in the recent kernel, try to pass ``enable_msi=0`` option to disable
145MSI.  If it works, you can add the known bad device to the blacklist
146defined in hda_intel.c.  In such a case, please report and give the
147patch back to the upstream developer.
148
149
150HD-Audio Codec
151==============
152
153Model Option
154------------
155The most common problem regarding the HD-audio driver is the
156unsupported codec features or the mismatched device configuration.
157Most of codec-specific code has several preset models, either to
158override the BIOS setup or to provide more comprehensive features.
159
160The driver checks PCI SSID and looks through the static configuration
161table until any matching entry is found.  If you have a new machine,
162you may see a message like below:
163::
164
165    hda_codec: ALC880: BIOS auto-probing.
166
167Meanwhile, in the earlier versions, you would see a message like:
168::
169
170    hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
171
172Even if you see such a message, DON'T PANIC.  Take a deep breath and
173keep your towel.  First of all, it's an informational message, no
174warning, no error.  This means that the PCI SSID of your device isn't
175listed in the known preset model (white-)list.  But, this doesn't mean
176that the driver is broken.  Many codec-drivers provide the automatic
177configuration mechanism based on the BIOS setup.
178
179The HD-audio codec has usually "pin" widgets, and BIOS sets the default
180configuration of each pin, which indicates the location, the
181connection type, the jack color, etc.  The HD-audio driver can guess
182the right connection judging from these default configuration values.
183However -- some codec-support codes, such as patch_analog.c, don't
184support the automatic probing (yet as of 2.6.28).  And, BIOS is often,
185yes, pretty often broken.  It sets up wrong values and screws up the
186driver.
187
188The preset model (or recently called as "fix-up") is provided
189basically to overcome such a situation.  When the matching preset
190model is found in the white-list, the driver assumes the static
191configuration of that preset with the correct pin setup, etc.
192Thus, if you have a newer machine with a slightly different PCI SSID
193(or codec SSID) from the existing one, you may have a good chance to
194re-use the same model.  You can pass the ``model`` option to specify the
195preset model instead of PCI (and codec-) SSID look-up.
196
197What ``model`` option values are available depends on the codec chip.
198Check your codec chip from the codec proc file (see "Codec Proc-File"
199section below).  It will show the vendor/product name of your codec
200chip.  Then, see Documentation/sound/hd-audio/models.rst file,
201the section of HD-audio driver.  You can find a list of codecs
202and ``model`` options belonging to each codec.  For example, for Realtek
203ALC262 codec chip, pass ``model=ultra`` for devices that are compatible
204with Samsung Q1 Ultra.
205
206Thus, the first thing you can do for any brand-new, unsupported and
207non-working HD-audio hardware is to check HD-audio codec and several
208different ``model`` option values.  If you have any luck, some of them
209might suit with your device well.
210
211There are a few special model option values:
212
213* when 'nofixup' is passed, the device-specific fixups in the codec
214  parser are skipped.
215* when ``generic`` is passed, the codec-specific parser is skipped and
216  only the generic parser is used.
217
218
219Speaker and Headphone Output
220----------------------------
221One of the most frequent (and obvious) bugs with HD-audio is the
222silent output from either or both of a built-in speaker and a
223headphone jack.  In general, you should try a headphone output at
224first.  A speaker output often requires more additional controls like
225the external amplifier bits.  Thus a headphone output has a slightly
226better chance.
227
228Before making a bug report, double-check whether the mixer is set up
229correctly.  The recent version of snd-hda-intel driver provides mostly
230"Master" volume control as well as "Front" volume (where Front
231indicates the front-channels).  In addition, there can be individual
232"Headphone" and "Speaker" controls.
233
234Ditto for the speaker output.  There can be "External Amplifier"
235switch on some codecs.  Turn on this if present.
236
237Another related problem is the automatic mute of speaker output by
238headphone plugging.  This feature is implemented in most cases, but
239not on every preset model or codec-support code.
240
241In anyway, try a different model option if you have such a problem.
242Some other models may match better and give you more matching
243functionality.  If none of the available models works, send a bug
244report.  See the bug report section for details.
245
246If you are masochistic enough to debug the driver problem, note the
247following:
248
249* The speaker (and the headphone, too) output often requires the
250  external amplifier.  This can be set usually via EAPD verb or a
251  certain GPIO.  If the codec pin supports EAPD, you have a better
252  chance via SET_EAPD_BTL verb (0x70c).  On others, GPIO pin (mostly
253  it's either GPIO0 or GPIO1) may turn on/off EAPD.
254* Some Realtek codecs require special vendor-specific coefficients to
255  turn on the amplifier.  See patch_realtek.c.
256* IDT codecs may have extra power-enable/disable controls on each
257  analog pin.  See patch_sigmatel.c.
258* Very rare but some devices don't accept the pin-detection verb until
259  triggered.  Issuing GET_PIN_SENSE verb (0xf09) may result in the
260  codec-communication stall.  Some examples are found in
261  patch_realtek.c.
262
263
264Capture Problems
265----------------
266The capture problems are often because of missing setups of mixers.
267Thus, before submitting a bug report, make sure that you set up the
268mixer correctly.  For example, both "Capture Volume" and "Capture
269Switch" have to be set properly in addition to the right "Capture
270Source" or "Input Source" selection.  Some devices have "Mic Boost"
271volume or switch.
272
273When the PCM device is opened via "default" PCM (without pulse-audio
274plugin), you'll likely have "Digital Capture Volume" control as well.
275This is provided for the extra gain/attenuation of the signal in
276software, especially for the inputs without the hardware volume
277control such as digital microphones.  Unless really needed, this
278should be set to exactly 50%, corresponding to 0dB -- neither extra
279gain nor attenuation.  When you use "hw" PCM, i.e., a raw access PCM,
280this control will have no influence, though.
281
282It's known that some codecs / devices have fairly bad analog circuits,
283and the recorded sound contains a certain DC-offset.  This is no bug
284of the driver.
285
286Most of modern laptops have no analog CD-input connection.  Thus, the
287recording from CD input won't work in many cases although the driver
288provides it as the capture source.  Use CDDA instead.
289
290The automatic switching of the built-in and external mic per plugging
291is implemented on some codec models but not on every model.  Partly
292because of my laziness but mostly lack of testers.  Feel free to
293submit the improvement patch to the author.
294
295
296Direct Debugging
297----------------
298If no model option gives you a better result, and you are a tough guy
299to fight against evil, try debugging via hitting the raw HD-audio
300codec verbs to the device.  Some tools are available: hda-emu and
301hda-analyzer.  The detailed description is found in the sections
302below.  You'd need to enable hwdep for using these tools.  See "Kernel
303Configuration" section.
304
305
306Other Issues
307============
308
309Kernel Configuration
310--------------------
311In general, I recommend you to enable the sound debug option,
312``CONFIG_SND_DEBUG=y``, no matter whether you are debugging or not.
313This enables snd_printd() macro and others, and you'll get additional
314kernel messages at probing.
315
316In addition, you can enable ``CONFIG_SND_DEBUG_VERBOSE=y``.  But this
317will give you far more messages.  Thus turn this on only when you are
318sure to want it.
319
320Don't forget to turn on the appropriate ``CONFIG_SND_HDA_CODEC_*``
321options.  Note that each of them corresponds to the codec chip, not
322the controller chip.  Thus, even if lspci shows the Nvidia controller,
323you may need to choose the option for other vendors.  If you are
324unsure, just select all yes.
325
326``CONFIG_SND_HDA_HWDEP`` is a useful option for debugging the driver.
327When this is enabled, the driver creates hardware-dependent devices
328(one per each codec), and you have a raw access to the device via
329these device files.  For example, ``hwC0D2`` will be created for the
330codec slot #2 of the first card (#0).  For debug-tools such as
331hda-verb and hda-analyzer, the hwdep device has to be enabled.
332Thus, it'd be better to turn this on always.
333
334``CONFIG_SND_HDA_RECONFIG`` is a new option, and this depends on the
335hwdep option above.  When enabled, you'll have some sysfs files under
336the corresponding hwdep directory.  See "HD-audio reconfiguration"
337section below.
338
339``CONFIG_SND_HDA_POWER_SAVE`` option enables the power-saving feature.
340See "Power-saving" section below.
341
342
343Codec Proc-File
344---------------
345The codec proc-file is a treasure-chest for debugging HD-audio.
346It shows most of useful information of each codec widget.
347
348The proc file is located in /proc/asound/card*/codec#*, one file per
349each codec slot.  You can know the codec vendor, product id and
350names, the type of each widget, capabilities and so on.
351This file, however, doesn't show the jack sensing state, so far.  This
352is because the jack-sensing might be depending on the trigger state.
353
354This file will be picked up by the debug tools, and also it can be fed
355to the emulator as the primary codec information.  See the debug tools
356section below.
357
358This proc file can be also used to check whether the generic parser is
359used.  When the generic parser is used, the vendor/product ID name
360will appear as "Realtek ID 0262", instead of "Realtek ALC262".
361
362
363HD-Audio Reconfiguration
364------------------------
365This is an experimental feature to allow you re-configure the HD-audio
366codec dynamically without reloading the driver.  The following sysfs
367files are available under each codec-hwdep device directory (e.g.
368/sys/class/sound/hwC0D0):
369
370vendor_id
371    Shows the 32bit codec vendor-id hex number.  You can change the
372    vendor-id value by writing to this file.
373subsystem_id
374    Shows the 32bit codec subsystem-id hex number.  You can change the
375    subsystem-id value by writing to this file.
376revision_id
377    Shows the 32bit codec revision-id hex number.  You can change the
378    revision-id value by writing to this file.
379afg
380    Shows the AFG ID.  This is read-only.
381mfg
382    Shows the MFG ID.  This is read-only.
383name
384    Shows the codec name string.  Can be changed by writing to this
385    file.
386modelname
387    Shows the currently set ``model`` option.  Can be changed by writing
388    to this file.
389init_verbs
390    The extra verbs to execute at initialization.  You can add a verb by
391    writing to this file.  Pass three numbers: nid, verb and parameter
392    (separated with a space).
393hints
394    Shows / stores hint strings for codec parsers for any use.
395    Its format is ``key = value``.  For example, passing ``jack_detect = no``
396    will disable the jack detection of the machine completely.
397init_pin_configs
398    Shows the initial pin default config values set by BIOS.
399driver_pin_configs
400    Shows the pin default values set by the codec parser explicitly.
401    This doesn't show all pin values but only the changed values by
402    the parser.  That is, if the parser doesn't change the pin default
403    config values by itself, this will contain nothing.
404user_pin_configs
405    Shows the pin default config values to override the BIOS setup.
406    Writing this (with two numbers, NID and value) appends the new
407    value.  The given will be used instead of the initial BIOS value at
408    the next reconfiguration time.  Note that this config will override
409    even the driver pin configs, too.
410reconfig
411    Triggers the codec re-configuration.  When any value is written to
412    this file, the driver re-initialize and parses the codec tree
413    again.  All the changes done by the sysfs entries above are taken
414    into account.
415clear
416    Resets the codec, removes the mixer elements and PCM stuff of the
417    specified codec, and clear all init verbs and hints.
418
419For example, when you want to change the pin default configuration
420value of the pin widget 0x14 to 0x9993013f, and let the driver
421re-configure based on that state, run like below:
422::
423
424    # echo 0x14 0x9993013f > /sys/class/sound/hwC0D0/user_pin_configs
425    # echo 1 > /sys/class/sound/hwC0D0/reconfig
426
427
428Hint Strings
429------------
430The codec parser have several switches and adjustment knobs for
431matching better with the actual codec or device behavior.  Many of
432them can be adjusted dynamically via "hints" strings as mentioned in
433the section above.  For example, by passing ``jack_detect = no`` string
434via sysfs or a patch file, you can disable the jack detection, thus
435the codec parser will skip the features like auto-mute or mic
436auto-switch.  As a boolean value, either ``yes``, ``no``, ``true``, ``false``,
437``1`` or ``0`` can be passed.
438
439The generic parser supports the following hints:
440
441jack_detect (bool)
442    specify whether the jack detection is available at all on this
443    machine; default true
444inv_jack_detect (bool)
445    indicates that the jack detection logic is inverted
446trigger_sense (bool)
447    indicates that the jack detection needs the explicit call of
448    AC_VERB_SET_PIN_SENSE verb
449inv_eapd (bool)
450    indicates that the EAPD is implemented in the inverted logic
451pcm_format_first (bool)
452    sets the PCM format before the stream tag and channel ID
453sticky_stream (bool)
454    keep the PCM format, stream tag and ID as long as possible;
455    default true
456spdif_status_reset (bool)
457    reset the SPDIF status bits at each time the SPDIF stream is set
458    up
459pin_amp_workaround (bool)
460    the output pin may have multiple amp values
461single_adc_amp (bool)
462    ADCs can have only single input amps
463auto_mute (bool)
464    enable/disable the headphone auto-mute feature; default true
465auto_mic (bool)
466    enable/disable the mic auto-switch feature; default true
467line_in_auto_switch (bool)
468    enable/disable the line-in auto-switch feature; default false
469need_dac_fix (bool)
470    limits the DACs depending on the channel count
471primary_hp (bool)
472    probe headphone jacks as the primary outputs; default true
473multi_io (bool)
474    try probing multi-I/O config (e.g. shared line-in/surround,
475    mic/clfe jacks)
476multi_cap_vol (bool)
477    provide multiple capture volumes
478inv_dmic_split (bool)
479    provide split internal mic volume/switch for phase-inverted
480    digital mics
481indep_hp (bool)
482    provide the independent headphone PCM stream and the corresponding
483    mixer control, if available
484add_stereo_mix_input (bool)
485    add the stereo mix (analog-loopback mix) to the input mux if
486    available
487add_jack_modes (bool)
488    add "xxx Jack Mode" enum controls to each I/O jack for allowing to
489    change the headphone amp and mic bias VREF capabilities
490power_save_node (bool)
491    advanced power management for each widget, controlling the power
492    sate (D0/D3) of each widget node depending on the actual pin and
493    stream states
494power_down_unused (bool)
495    power down the unused widgets, a subset of power_save_node, and
496    will be dropped in future
497add_hp_mic (bool)
498    add the headphone to capture source if possible
499hp_mic_detect (bool)
500    enable/disable the hp/mic shared input for a single built-in mic
501    case; default true
502vmaster (bool)
503    enable/disable the virtual Master control; default true
504mixer_nid (int)
505    specifies the widget NID of the analog-loopback mixer
506
507
508Early Patching
509--------------
510When ``CONFIG_SND_HDA_PATCH_LOADER=y`` is set, you can pass a "patch"
511as a firmware file for modifying the HD-audio setup before
512initializing the codec.  This can work basically like the
513reconfiguration via sysfs in the above, but it does it before the
514first codec configuration.
515
516A patch file is a plain text file which looks like below:
517
518::
519
520    [codec]
521    0x12345678 0xabcd1234 2
522
523    [model]
524    auto
525
526    [pincfg]
527    0x12 0x411111f0
528
529    [verb]
530    0x20 0x500 0x03
531    0x20 0x400 0xff
532
533    [hint]
534    jack_detect = no
535
536
537The file needs to have a line ``[codec]``.  The next line should contain
538three numbers indicating the codec vendor-id (0x12345678 in the
539example), the codec subsystem-id (0xabcd1234) and the address (2) of
540the codec.  The rest patch entries are applied to this specified codec
541until another codec entry is given.  Passing 0 or a negative number to
542the first or the second value will make the check of the corresponding
543field be skipped.  It'll be useful for really broken devices that don't
544initialize SSID properly.
545
546The ``[model]`` line allows to change the model name of the each codec.
547In the example above, it will be changed to model=auto.
548Note that this overrides the module option.
549
550After the ``[pincfg]`` line, the contents are parsed as the initial
551default pin-configurations just like ``user_pin_configs`` sysfs above.
552The values can be shown in user_pin_configs sysfs file, too.
553
554Similarly, the lines after ``[verb]`` are parsed as ``init_verbs``
555sysfs entries, and the lines after ``[hint]`` are parsed as ``hints``
556sysfs entries, respectively.
557
558Another example to override the codec vendor id from 0x12345678 to
5590xdeadbeef is like below:
560::
561
562    [codec]
563    0x12345678 0xabcd1234 2
564
565    [vendor_id]
566    0xdeadbeef
567
568
569In the similar way, you can override the codec subsystem_id via
570``[subsystem_id]``, the revision id via ``[revision_id]`` line.
571Also, the codec chip name can be rewritten via ``[chip_name]`` line.
572::
573
574    [codec]
575    0x12345678 0xabcd1234 2
576
577    [subsystem_id]
578    0xffff1111
579
580    [revision_id]
581    0x10
582
583    [chip_name]
584    My-own NEWS-0002
585
586
587The hd-audio driver reads the file via request_firmware().  Thus,
588a patch file has to be located on the appropriate firmware path,
589typically, /lib/firmware.  For example, when you pass the option
590``patch=hda-init.fw``, the file /lib/firmware/hda-init.fw must be
591present.
592
593The patch module option is specific to each card instance, and you
594need to give one file name for each instance, separated by commas.
595For example, if you have two cards, one for an on-board analog and one
596for an HDMI video board, you may pass patch option like below:
597::
598
599    options snd-hda-intel patch=on-board-patch,hdmi-patch
600
601
602Power-Saving
603------------
604The power-saving is a kind of auto-suspend of the device.  When the
605device is inactive for a certain time, the device is automatically
606turned off to save the power.  The time to go down is specified via
607``power_save`` module option, and this option can be changed dynamically
608via sysfs.
609
610The power-saving won't work when the analog loopback is enabled on
611some codecs.  Make sure that you mute all unneeded signal routes when
612you want the power-saving.
613
614The power-saving feature might cause audible click noises at each
615power-down/up depending on the device.  Some of them might be
616solvable, but some are hard, I'm afraid.  Some distros such as
617openSUSE enables the power-saving feature automatically when the power
618cable is unplugged.  Thus, if you hear noises, suspect first the
619power-saving.  See /sys/module/snd_hda_intel/parameters/power_save to
620check the current value.  If it's non-zero, the feature is turned on.
621
622The recent kernel supports the runtime PM for the HD-audio controller
623chip, too.  It means that the HD-audio controller is also powered up /
624down dynamically.  The feature is enabled only for certain controller
625chips like Intel LynxPoint.  You can enable/disable this feature
626forcibly by setting ``power_save_controller`` option, which is also
627available at /sys/module/snd_hda_intel/parameters directory.
628
629
630Tracepoints
631-----------
632The hd-audio driver gives a few basic tracepoints.
633``hda:hda_send_cmd`` traces each CORB write while ``hda:hda_get_response``
634traces the response from RIRB (only when read from the codec driver).
635``hda:hda_bus_reset`` traces the bus-reset due to fatal error, etc,
636``hda:hda_unsol_event`` traces the unsolicited events, and
637``hda:hda_power_down`` and ``hda:hda_power_up`` trace the power down/up
638via power-saving behavior.
639
640Enabling all tracepoints can be done like
641::
642
643    # echo 1 > /sys/kernel/debug/tracing/events/hda/enable
644
645then after some commands, you can traces from
646/sys/kernel/debug/tracing/trace file.  For example, when you want to
647trace what codec command is sent, enable the tracepoint like:
648::
649
650    # cat /sys/kernel/debug/tracing/trace
651    # tracer: nop
652    #
653    #       TASK-PID    CPU#    TIMESTAMP  FUNCTION
654    #          | |       |          |         |
655	   <...>-7807  [002] 105147.774889: hda_send_cmd: [0:0] val=e3a019
656	   <...>-7807  [002] 105147.774893: hda_send_cmd: [0:0] val=e39019
657	   <...>-7807  [002] 105147.999542: hda_send_cmd: [0:0] val=e3a01a
658	   <...>-7807  [002] 105147.999543: hda_send_cmd: [0:0] val=e3901a
659	   <...>-26764 [001] 349222.837143: hda_send_cmd: [0:0] val=e3a019
660	   <...>-26764 [001] 349222.837148: hda_send_cmd: [0:0] val=e39019
661	   <...>-26764 [001] 349223.058539: hda_send_cmd: [0:0] val=e3a01a
662	   <...>-26764 [001] 349223.058541: hda_send_cmd: [0:0] val=e3901a
663
664Here ``[0:0]`` indicates the card number and the codec address, and
665``val`` shows the value sent to the codec, respectively.  The value is
666a packed value, and you can decode it via hda-decode-verb program
667included in hda-emu package below.  For example, the value e3a019 is
668to set the left output-amp value to 25.
669::
670
671    % hda-decode-verb 0xe3a019
672    raw value = 0x00e3a019
673    cid = 0, nid = 0x0e, verb = 0x3a0, parm = 0x19
674    raw value: verb = 0x3a0, parm = 0x19
675    verbname = set_amp_gain_mute
676    amp raw val = 0xa019
677    output, left, idx=0, mute=0, val=25
678
679
680Development Tree
681----------------
682The latest development codes for HD-audio are found on sound git tree:
683
684* git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
685
686The master branch or for-next branches can be used as the main
687development branches in general while the development for the current
688and next kernels are found in for-linus and for-next branches,
689respectively.
690
691
692Sending a Bug Report
693--------------------
694If any model or module options don't work for your device, it's time
695to send a bug report to the developers.  Give the following in your
696bug report:
697
698* Hardware vendor, product and model names
699* Kernel version (and ALSA-driver version if you built externally)
700* ``alsa-info.sh`` output; run with ``--no-upload`` option.  See the
701  section below about alsa-info
702
703If it's a regression, at best, send alsa-info outputs of both working
704and non-working kernels.  This is really helpful because we can
705compare the codec registers directly.
706
707Send a bug report either the following:
708
709kernel-bugzilla
710    https://bugzilla.kernel.org/
711alsa-devel ML
712    alsa-devel@alsa-project.org
713
714
715Debug Tools
716===========
717
718This section describes some tools available for debugging HD-audio
719problems.
720
721alsa-info
722---------
723The script ``alsa-info.sh`` is a very useful tool to gather the audio
724device information.  It's included in alsa-utils package.  The latest
725version can be found on git repository:
726
727* git://git.alsa-project.org/alsa-utils.git
728
729The script can be fetched directly from the following URL, too:
730
731* https://www.alsa-project.org/alsa-info.sh
732
733Run this script as root, and it will gather the important information
734such as the module lists, module parameters, proc file contents
735including the codec proc files, mixer outputs and the control
736elements.  As default, it will store the information onto a web server
737on alsa-project.org.  But, if you send a bug report, it'd be better to
738run with ``--no-upload`` option, and attach the generated file.
739
740There are some other useful options.  See ``--help`` option output for
741details.
742
743When a probe error occurs or when the driver obviously assigns a
744mismatched model, it'd be helpful to load the driver with
745``probe_only=1`` option (at best after the cold reboot) and run
746alsa-info at this state.  With this option, the driver won't configure
747the mixer and PCM but just tries to probe the codec slot.  After
748probing, the proc file is available, so you can get the raw codec
749information before modified by the driver.  Of course, the driver
750isn't usable with ``probe_only=1``.  But you can continue the
751configuration via hwdep sysfs file if hda-reconfig option is enabled.
752Using ``probe_only`` mask 2 skips the reset of HDA codecs (use
753``probe_only=3`` as module option). The hwdep interface can be used
754to determine the BIOS codec initialization.
755
756
757hda-verb
758--------
759hda-verb is a tiny program that allows you to access the HD-audio
760codec directly.  You can execute a raw HD-audio codec verb with this.
761This program accesses the hwdep device, thus you need to enable the
762kernel config ``CONFIG_SND_HDA_HWDEP=y`` beforehand.
763
764The hda-verb program takes four arguments: the hwdep device file, the
765widget NID, the verb and the parameter.  When you access to the codec
766on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first
767argument, typically.  (However, the real path name depends on the
768system.)
769
770The second parameter is the widget number-id to access.  The third
771parameter can be either a hex/digit number or a string corresponding
772to a verb.  Similarly, the last parameter is the value to write, or
773can be a string for the parameter type.
774
775::
776
777    % hda-verb /dev/snd/hwC0D0 0x12 0x701 2
778    nid = 0x12, verb = 0x701, param = 0x2
779    value = 0x0
780
781    % hda-verb /dev/snd/hwC0D0 0x0 PARAMETERS VENDOR_ID
782    nid = 0x0, verb = 0xf00, param = 0x0
783    value = 0x10ec0262
784
785    % hda-verb /dev/snd/hwC0D0 2 set_a 0xb080
786    nid = 0x2, verb = 0x300, param = 0xb080
787    value = 0x0
788
789
790Although you can issue any verbs with this program, the driver state
791won't be always updated.  For example, the volume values are usually
792cached in the driver, and thus changing the widget amp value directly
793via hda-verb won't change the mixer value.
794
795The hda-verb program is included now in alsa-tools:
796
797* git://git.alsa-project.org/alsa-tools.git
798
799Also, the old stand-alone package is found in the ftp directory:
800
801* ftp://ftp.suse.com/pub/people/tiwai/misc/
802
803Also a git repository is available:
804
805* git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-verb.git
806
807See README file in the tarball for more details about hda-verb
808program.
809
810
811hda-analyzer
812------------
813hda-analyzer provides a graphical interface to access the raw HD-audio
814control, based on pyGTK2 binding.  It's a more powerful version of
815hda-verb.  The program gives you an easy-to-use GUI stuff for showing
816the widget information and adjusting the amp values, as well as the
817proc-compatible output.
818
819The hda-analyzer:
820
821* https://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer
822
823is a part of alsa.git repository in alsa-project.org:
824
825* git://git.alsa-project.org/alsa.git
826
827Codecgraph
828----------
829Codecgraph is a utility program to generate a graph and visualizes the
830codec-node connection of a codec chip.  It's especially useful when
831you analyze or debug a codec without a proper datasheet.  The program
832parses the given codec proc file and converts to SVG via graphiz
833program.
834
835The tarball and GIT trees are found in the web page at:
836
837* http://helllabs.org/codecgraph/
838
839
840hda-emu
841-------
842hda-emu is an HD-audio emulator.  The main purpose of this program is
843to debug an HD-audio codec without the real hardware.  Thus, it
844doesn't emulate the behavior with the real audio I/O, but it just
845dumps the codec register changes and the ALSA-driver internal changes
846at probing and operating the HD-audio driver.
847
848The program requires a codec proc-file to simulate.  Get a proc file
849for the target codec beforehand, or pick up an example codec from the
850codec proc collections in the tarball.  Then, run the program with the
851proc file, and the hda-emu program will start parsing the codec file
852and simulates the HD-audio driver:
853
854::
855
856    % hda-emu codecs/stac9200-dell-d820-laptop
857    # Parsing..
858    hda_codec: Unknown model for STAC9200, using BIOS defaults
859    hda_codec: pin nid 08 bios pin config 40c003fa
860    ....
861
862
863The program gives you only a very dumb command-line interface.  You
864can get a proc-file dump at the current state, get a list of control
865(mixer) elements, set/get the control element value, simulate the PCM
866operation, the jack plugging simulation, etc.
867
868The program is found in the git repository below:
869
870* git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-emu.git
871
872See README file in the repository for more details about hda-emu
873program.
874
875
876hda-jack-retask
877---------------
878hda-jack-retask is a user-friendly GUI program to manipulate the
879HD-audio pin control for jack retasking.  If you have a problem about
880the jack assignment, try this program and check whether you can get
881useful results.  Once when you figure out the proper pin assignment,
882it can be fixed either in the driver code statically or via passing a
883firmware patch file (see "Early Patching" section).
884
885The program is included in alsa-tools now:
886
887* git://git.alsa-project.org/alsa-tools.git
888