linux/Documentation/sound/alsa/HD-Audio.txt
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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 hardware 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.
  61`position_fix=3` means to use a combination of both methods, needed
  62for some VIA controllers.  The capture stream position is corrected
  63by comparing both LPIB and position-buffer values.
  64`position_fix=4` is another combination available for all controllers,
  65and uses LPIB for the playback and the position-buffer for the capture
  66streams.
  670 is the default value for all other
  68controllers, the automatic check and fallback to LPIB as described in
  69the above.  If you get a problem of repeated sounds, this option might
  70help.
  71
  72In addition to that, every controller is known to be broken regarding
  73the wake-up timing.  It wakes up a few samples before actually
  74processing the data on the buffer.  This caused a lot of problems, for
  75example, with ALSA dmix or JACK.  Since 2.6.27 kernel, the driver puts
  76an artificial delay to the wake up timing.  This delay is controlled
  77via `bdl_pos_adj` option. 
  78
  79When `bdl_pos_adj` is a negative value (as default), it's assigned to
  80an appropriate value depending on the controller chip.  For Intel
  81chips, it'd be 1 while it'd be 32 for others.  Usually this works.
  82Only in case it doesn't work and you get warning messages, you should
  83change this parameter to other values.
  84
  85
  86Codec-Probing Problem
  87~~~~~~~~~~~~~~~~~~~~~
  88A less often but a more severe problem is the codec probing.  When
  89BIOS reports the available codec slots wrongly, the driver gets
  90confused and tries to access the non-existing codec slot.  This often
  91results in the total screw-up, and destructs the further communication
  92with the codec chips.  The symptom appears usually as error messages
  93like:
  94------------------------------------------------------------------------
  95  hda_intel: azx_get_response timeout, switching to polling mode:
  96        last cmd=0x12345678
  97  hda_intel: azx_get_response timeout, switching to single_cmd mode:
  98        last cmd=0x12345678
  99------------------------------------------------------------------------
 100
 101The first line is a warning, and this is usually relatively harmless.
 102It means that the codec response isn't notified via an IRQ.  The
 103driver uses explicit polling method to read the response.  It gives
 104very slight CPU overhead, but you'd unlikely notice it.
 105
 106The second line is, however, a fatal error.  If this happens, usually
 107it means that something is really wrong.  Most likely you are
 108accessing a non-existing codec slot.
 109
 110Thus, if the second error message appears, try to narrow the probed
 111codec slots via `probe_mask` option.  It's a bitmask, and each bit
 112corresponds to the codec slot.  For example, to probe only the first
 113slot, pass `probe_mask=1`.  For the first and the third slots, pass
 114`probe_mask=5` (where 5 = 1 | 4), and so on.
 115
 116Since 2.6.29 kernel, the driver has a more robust probing method, so
 117this error might happen rarely, though.
 118
 119On a machine with a broken BIOS, sometimes you need to force the
 120driver to probe the codec slots the hardware doesn't report for use.
 121In such a case, turn the bit 8 (0x100) of `probe_mask` option on.
 122Then the rest 8 bits are passed as the codec slots to probe
 123unconditionally.  For example, `probe_mask=0x103` will force to probe
 124the codec slots 0 and 1 no matter what the hardware reports.
 125
 126
 127Interrupt Handling
 128~~~~~~~~~~~~~~~~~~
 129HD-audio driver uses MSI as default (if available) since 2.6.33
 130kernel as MSI works better on some machines, and in general, it's
 131better for performance.  However, Nvidia controllers showed bad
 132regressions with MSI (especially in a combination with AMD chipset),
 133thus we disabled MSI for them.
 134
 135There seem also still other devices that don't work with MSI.  If you
 136see a regression wrt the sound quality (stuttering, etc) or a lock-up
 137in the recent kernel, try to pass `enable_msi=0` option to disable
 138MSI.  If it works, you can add the known bad device to the blacklist
 139defined in hda_intel.c.  In such a case, please report and give the
 140patch back to the upstream developer. 
 141
 142
 143HD-AUDIO CODEC
 144--------------
 145
 146Model Option
 147~~~~~~~~~~~~
 148The most common problem regarding the HD-audio driver is the
 149unsupported codec features or the mismatched device configuration.
 150Most of codec-specific code has several preset models, either to
 151override the BIOS setup or to provide more comprehensive features.
 152
 153The driver checks PCI SSID and looks through the static configuration
 154table until any matching entry is found.  If you have a new machine,
 155you may see a message like below:
 156------------------------------------------------------------------------
 157    hda_codec: ALC880: BIOS auto-probing.
 158------------------------------------------------------------------------
 159Meanwhile, in the earlier versions, you would see a message like:
 160------------------------------------------------------------------------
 161    hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
 162------------------------------------------------------------------------
 163Even if you see such a message, DON'T PANIC.  Take a deep breath and
 164keep your towel.  First of all, it's an informational message, no
 165warning, no error.  This means that the PCI SSID of your device isn't
 166listed in the known preset model (white-)list.  But, this doesn't mean
 167that the driver is broken.  Many codec-drivers provide the automatic
 168configuration mechanism based on the BIOS setup.
 169
 170The HD-audio codec has usually "pin" widgets, and BIOS sets the default
 171configuration of each pin, which indicates the location, the
 172connection type, the jack color, etc.  The HD-audio driver can guess
 173the right connection judging from these default configuration values.
 174However -- some codec-support codes, such as patch_analog.c, don't
 175support the automatic probing (yet as of 2.6.28).  And, BIOS is often,
 176yes, pretty often broken.  It sets up wrong values and screws up the
 177driver.
 178
 179The preset model (or recently called as "fix-up") is provided
 180basically to overcome such a situation.  When the matching preset
 181model is found in the white-list, the driver assumes the static
 182configuration of that preset with the correct pin setup, etc.
 183Thus, if you have a newer machine with a slightly different PCI SSID
 184(or codec SSID) from the existing one, you may have a good chance to
 185re-use the same model.  You can pass the `model` option to specify the
 186preset model instead of PCI (and codec-) SSID look-up.
 187
 188What `model` option values are available depends on the codec chip.
 189Check your codec chip from the codec proc file (see "Codec Proc-File"
 190section below).  It will show the vendor/product name of your codec
 191chip.  Then, see Documentation/sound/alsa/HD-Audio-Models.txt file,
 192the section of HD-audio driver.  You can find a list of codecs
 193and `model` options belonging to each codec.  For example, for Realtek
 194ALC262 codec chip, pass `model=ultra` for devices that are compatible
 195with Samsung Q1 Ultra.
 196
 197Thus, the first thing you can do for any brand-new, unsupported and
 198non-working HD-audio hardware is to check HD-audio codec and several
 199different `model` option values.  If you have any luck, some of them
 200might suit with your device well.
 201
 202There are a few special model option values:
 203- when 'nofixup' is passed, the device-specific fixups in the codec
 204  parser are skipped.
 205- when `generic` is passed, the codec-specific parser is skipped and
 206  only the generic parser is used.
 207
 208
 209Speaker and Headphone Output
 210~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 211One of the most frequent (and obvious) bugs with HD-audio is the
 212silent output from either or both of a built-in speaker and a
 213headphone jack.  In general, you should try a headphone output at
 214first.  A speaker output often requires more additional controls like
 215the external amplifier bits.  Thus a headphone output has a slightly
 216better chance.
 217
 218Before making a bug report, double-check whether the mixer is set up
 219correctly.  The recent version of snd-hda-intel driver provides mostly
 220"Master" volume control as well as "Front" volume (where Front
 221indicates the front-channels).  In addition, there can be individual
 222"Headphone" and "Speaker" controls.
 223
 224Ditto for the speaker output.  There can be "External Amplifier"
 225switch on some codecs.  Turn on this if present.
 226
 227Another related problem is the automatic mute of speaker output by
 228headphone plugging.  This feature is implemented in most cases, but
 229not on every preset model or codec-support code.
 230
 231In anyway, try a different model option if you have such a problem.
 232Some other models may match better and give you more matching
 233functionality.  If none of the available models works, send a bug
 234report.  See the bug report section for details.
 235
 236If you are masochistic enough to debug the driver problem, note the
 237following:
 238
 239- The speaker (and the headphone, too) output often requires the
 240  external amplifier.  This can be set usually via EAPD verb or a
 241  certain GPIO.  If the codec pin supports EAPD, you have a better
 242  chance via SET_EAPD_BTL verb (0x70c).  On others, GPIO pin (mostly
 243  it's either GPIO0 or GPIO1) may turn on/off EAPD.
 244- Some Realtek codecs require special vendor-specific coefficients to
 245  turn on the amplifier.  See patch_realtek.c.
 246- IDT codecs may have extra power-enable/disable controls on each
 247  analog pin.  See patch_sigmatel.c.
 248- Very rare but some devices don't accept the pin-detection verb until
 249  triggered.  Issuing GET_PIN_SENSE verb (0xf09) may result in the
 250  codec-communication stall.  Some examples are found in
 251  patch_realtek.c.
 252
 253
 254Capture Problems
 255~~~~~~~~~~~~~~~~
 256The capture problems are often because of missing setups of mixers.
 257Thus, before submitting a bug report, make sure that you set up the
 258mixer correctly.  For example, both "Capture Volume" and "Capture
 259Switch" have to be set properly in addition to the right "Capture
 260Source" or "Input Source" selection.  Some devices have "Mic Boost"
 261volume or switch.
 262
 263When the PCM device is opened via "default" PCM (without pulse-audio
 264plugin), you'll likely have "Digital Capture Volume" control as well.
 265This is provided for the extra gain/attenuation of the signal in
 266software, especially for the inputs without the hardware volume
 267control such as digital microphones.  Unless really needed, this
 268should be set to exactly 50%, corresponding to 0dB -- neither extra
 269gain nor attenuation.  When you use "hw" PCM, i.e., a raw access PCM,
 270this control will have no influence, though.
 271
 272It's known that some codecs / devices have fairly bad analog circuits,
 273and the recorded sound contains a certain DC-offset.  This is no bug
 274of the driver.
 275
 276Most of modern laptops have no analog CD-input connection.  Thus, the
 277recording from CD input won't work in many cases although the driver
 278provides it as the capture source.  Use CDDA instead.
 279
 280The automatic switching of the built-in and external mic per plugging
 281is implemented on some codec models but not on every model.  Partly
 282because of my laziness but mostly lack of testers.  Feel free to
 283submit the improvement patch to the author.
 284
 285
 286Direct Debugging
 287~~~~~~~~~~~~~~~~
 288If no model option gives you a better result, and you are a tough guy
 289to fight against evil, try debugging via hitting the raw HD-audio
 290codec verbs to the device.  Some tools are available: hda-emu and
 291hda-analyzer.  The detailed description is found in the sections
 292below.  You'd need to enable hwdep for using these tools.  See "Kernel
 293Configuration" section.
 294
 295
 296OTHER ISSUES
 297------------
 298
 299Kernel Configuration
 300~~~~~~~~~~~~~~~~~~~~
 301In general, I recommend you to enable the sound debug option,
 302`CONFIG_SND_DEBUG=y`, no matter whether you are debugging or not.
 303This enables snd_printd() macro and others, and you'll get additional
 304kernel messages at probing.
 305
 306In addition, you can enable `CONFIG_SND_DEBUG_VERBOSE=y`.  But this
 307will give you far more messages.  Thus turn this on only when you are
 308sure to want it.
 309
 310Don't forget to turn on the appropriate `CONFIG_SND_HDA_CODEC_*`
 311options.  Note that each of them corresponds to the codec chip, not
 312the controller chip.  Thus, even if lspci shows the Nvidia controller,
 313you may need to choose the option for other vendors.  If you are
 314unsure, just select all yes.
 315
 316`CONFIG_SND_HDA_HWDEP` is a useful option for debugging the driver.
 317When this is enabled, the driver creates hardware-dependent devices
 318(one per each codec), and you have a raw access to the device via
 319these device files.  For example, `hwC0D2` will be created for the
 320codec slot #2 of the first card (#0).  For debug-tools such as
 321hda-verb and hda-analyzer, the hwdep device has to be enabled.
 322Thus, it'd be better to turn this on always.
 323
 324`CONFIG_SND_HDA_RECONFIG` is a new option, and this depends on the
 325hwdep option above.  When enabled, you'll have some sysfs files under
 326the corresponding hwdep directory.  See "HD-audio reconfiguration"
 327section below.
 328
 329`CONFIG_SND_HDA_POWER_SAVE` option enables the power-saving feature.
 330See "Power-saving" section below.
 331
 332
 333Codec Proc-File
 334~~~~~~~~~~~~~~~
 335The codec proc-file is a treasure-chest for debugging HD-audio.
 336It shows most of useful information of each codec widget.
 337
 338The proc file is located in /proc/asound/card*/codec#*, one file per
 339each codec slot.  You can know the codec vendor, product id and
 340names, the type of each widget, capabilities and so on.
 341This file, however, doesn't show the jack sensing state, so far.  This
 342is because the jack-sensing might be depending on the trigger state.
 343
 344This file will be picked up by the debug tools, and also it can be fed
 345to the emulator as the primary codec information.  See the debug tools
 346section below.
 347
 348This proc file can be also used to check whether the generic parser is
 349used.  When the generic parser is used, the vendor/product ID name
 350will appear as "Realtek ID 0262", instead of "Realtek ALC262".
 351
 352
 353HD-Audio Reconfiguration
 354~~~~~~~~~~~~~~~~~~~~~~~~
 355This is an experimental feature to allow you re-configure the HD-audio
 356codec dynamically without reloading the driver.  The following sysfs
 357files are available under each codec-hwdep device directory (e.g. 
 358/sys/class/sound/hwC0D0):
 359
 360vendor_id::
 361  Shows the 32bit codec vendor-id hex number.  You can change the
 362  vendor-id value by writing to this file.
 363subsystem_id::
 364  Shows the 32bit codec subsystem-id hex number.  You can change the
 365  subsystem-id value by writing to this file.
 366revision_id::
 367  Shows the 32bit codec revision-id hex number.  You can change the
 368  revision-id value by writing to this file.
 369afg::
 370  Shows the AFG ID.  This is read-only.
 371mfg::
 372  Shows the MFG ID.  This is read-only.
 373name::
 374  Shows the codec name string.  Can be changed by writing to this
 375  file.
 376modelname::
 377  Shows the currently set `model` option.  Can be changed by writing
 378  to this file.
 379init_verbs::
 380  The extra verbs to execute at initialization.  You can add a verb by
 381  writing to this file.  Pass three numbers: nid, verb and parameter
 382  (separated with a space).
 383hints::
 384  Shows / stores hint strings for codec parsers for any use.
 385  Its format is `key = value`.  For example, passing `jack_detect = no`
 386  will disable the jack detection of the machine completely.
 387init_pin_configs::
 388  Shows the initial pin default config values set by BIOS.
 389driver_pin_configs::
 390  Shows the pin default values set by the codec parser explicitly.
 391  This doesn't show all pin values but only the changed values by
 392  the parser.  That is, if the parser doesn't change the pin default
 393  config values by itself, this will contain nothing.
 394user_pin_configs::
 395  Shows the pin default config values to override the BIOS setup.
 396  Writing this (with two numbers, NID and value) appends the new
 397  value.  The given will be used instead of the initial BIOS value at
 398  the next reconfiguration time.  Note that this config will override
 399  even the driver pin configs, too.
 400reconfig::
 401  Triggers the codec re-configuration.  When any value is written to
 402  this file, the driver re-initialize and parses the codec tree
 403  again.  All the changes done by the sysfs entries above are taken
 404  into account.
 405clear::
 406  Resets the codec, removes the mixer elements and PCM stuff of the
 407  specified codec, and clear all init verbs and hints.
 408
 409For example, when you want to change the pin default configuration
 410value of the pin widget 0x14 to 0x9993013f, and let the driver
 411re-configure based on that state, run like below:
 412------------------------------------------------------------------------
 413  # echo 0x14 0x9993013f > /sys/class/sound/hwC0D0/user_pin_configs
 414  # echo 1 > /sys/class/sound/hwC0D0/reconfig  
 415------------------------------------------------------------------------
 416
 417
 418Hint Strings
 419~~~~~~~~~~~~
 420The codec parser have several switches and adjustment knobs for
 421matching better with the actual codec or device behavior.  Many of
 422them can be adjusted dynamically via "hints" strings as mentioned in
 423the section above.  For example, by passing `jack_detect = no` string
 424via sysfs or a patch file, you can disable the jack detection, thus
 425the codec parser will skip the features like auto-mute or mic
 426auto-switch.  As a boolean value, either `yes`, `no`, `true`, `false`,
 427`1` or `0` can be passed.
 428
 429The generic parser supports the following hints:
 430
 431- jack_detect (bool): specify whether the jack detection is available
 432  at all on this machine; default true
 433- inv_jack_detect (bool): indicates that the jack detection logic is
 434  inverted
 435- trigger_sense (bool): indicates that the jack detection needs the
 436  explicit call of AC_VERB_SET_PIN_SENSE verb
 437- inv_eapd (bool): indicates that the EAPD is implemented in the
 438  inverted logic
 439- pcm_format_first (bool): sets the PCM format before the stream tag
 440  and channel ID
 441- sticky_stream (bool): keep the PCM format, stream tag and ID as long
 442  as possible; default true
 443- spdif_status_reset (bool): reset the SPDIF status bits at each time
 444  the SPDIF stream is set up
 445-  pin_amp_workaround (bool): the output pin may have multiple amp
 446  values
 447- single_adc_amp (bool): ADCs can have only single input amps
 448- auto_mute (bool): enable/disable the headphone auto-mute feature;
 449  default true
 450- auto_mic (bool): enable/disable the mic auto-switch feature; default
 451  true
 452- line_in_auto_switch (bool): enable/disable the line-in auto-switch
 453  feature; default false
 454- need_dac_fix (bool): limits the DACs depending on the channel count
 455- primary_hp (bool): probe headphone jacks as the primary outputs;
 456  default true
 457- multi_cap_vol (bool): provide multiple capture volumes
 458- inv_dmic_split (bool): provide split internal mic volume/switch for
 459  phase-inverted digital mics
 460- indep_hp (bool): provide the independent headphone PCM stream and
 461  the corresponding mixer control, if available
 462- add_stereo_mix_input (bool): add the stereo mix (analog-loopback
 463  mix) to the input mux if available
 464- add_jack_modes (bool): add "xxx Jack Mode" enum controls to each
 465  I/O jack for allowing to change the headphone amp and mic bias VREF
 466  capabilities
 467- power_down_unused (bool): power down the unused widgets
 468- add_hp_mic (bool): add the headphone to capture source if possible
 469- hp_mic_detect (bool): enable/disable the hp/mic shared input for a
 470  single built-in mic case; default true
 471- mixer_nid (int): specifies the widget NID of the analog-loopback
 472  mixer
 473
 474
 475Early Patching
 476~~~~~~~~~~~~~~
 477When CONFIG_SND_HDA_PATCH_LOADER=y is set, you can pass a "patch" as a
 478firmware file for modifying the HD-audio setup before initializing the
 479codec.  This can work basically like the reconfiguration via sysfs in
 480the above, but it does it before the first codec configuration.
 481
 482A patch file is a plain text file which looks like below:
 483
 484------------------------------------------------------------------------
 485  [codec]
 486  0x12345678 0xabcd1234 2
 487
 488  [model]
 489  auto
 490
 491  [pincfg]
 492  0x12 0x411111f0
 493
 494  [verb]
 495  0x20 0x500 0x03
 496  0x20 0x400 0xff
 497
 498  [hint]
 499  jack_detect = no
 500------------------------------------------------------------------------
 501
 502The file needs to have a line `[codec]`.  The next line should contain
 503three numbers indicating the codec vendor-id (0x12345678 in the
 504example), the codec subsystem-id (0xabcd1234) and the address (2) of
 505the codec.  The rest patch entries are applied to this specified codec
 506until another codec entry is given.  Passing 0 or a negative number to
 507the first or the second value will make the check of the corresponding
 508field be skipped.  It'll be useful for really broken devices that don't
 509initialize SSID properly.
 510
 511The `[model]` line allows to change the model name of the each codec.
 512In the example above, it will be changed to model=auto.
 513Note that this overrides the module option.
 514
 515After the `[pincfg]` line, the contents are parsed as the initial
 516default pin-configurations just like `user_pin_configs` sysfs above.
 517The values can be shown in user_pin_configs sysfs file, too.
 518
 519Similarly, the lines after `[verb]` are parsed as `init_verbs`
 520sysfs entries, and the lines after `[hint]` are parsed as `hints`
 521sysfs entries, respectively.
 522
 523Another example to override the codec vendor id from 0x12345678 to
 5240xdeadbeef is like below:
 525------------------------------------------------------------------------
 526  [codec]
 527  0x12345678 0xabcd1234 2
 528
 529  [vendor_id]
 530  0xdeadbeef
 531------------------------------------------------------------------------
 532
 533In the similar way, you can override the codec subsystem_id via
 534`[subsystem_id]`, the revision id via `[revision_id]` line.
 535Also, the codec chip name can be rewritten via `[chip_name]` line.
 536------------------------------------------------------------------------
 537  [codec]
 538  0x12345678 0xabcd1234 2
 539
 540  [subsystem_id]
 541  0xffff1111
 542
 543  [revision_id]
 544  0x10
 545
 546  [chip_name]
 547  My-own NEWS-0002
 548------------------------------------------------------------------------
 549
 550The hd-audio driver reads the file via request_firmware().  Thus,
 551a patch file has to be located on the appropriate firmware path,
 552typically, /lib/firmware.  For example, when you pass the option
 553`patch=hda-init.fw`, the file /lib/firmware/hda-init.fw must be
 554present.
 555
 556The patch module option is specific to each card instance, and you
 557need to give one file name for each instance, separated by commas.
 558For example, if you have two cards, one for an on-board analog and one 
 559for an HDMI video board, you may pass patch option like below:
 560------------------------------------------------------------------------
 561    options snd-hda-intel patch=on-board-patch,hdmi-patch
 562------------------------------------------------------------------------
 563
 564
 565Power-Saving
 566~~~~~~~~~~~~
 567The power-saving is a kind of auto-suspend of the device.  When the
 568device is inactive for a certain time, the device is automatically
 569turned off to save the power.  The time to go down is specified via
 570`power_save` module option, and this option can be changed dynamically
 571via sysfs.
 572
 573The power-saving won't work when the analog loopback is enabled on
 574some codecs.  Make sure that you mute all unneeded signal routes when
 575you want the power-saving.
 576
 577The power-saving feature might cause audible click noises at each
 578power-down/up depending on the device.  Some of them might be
 579solvable, but some are hard, I'm afraid.  Some distros such as
 580openSUSE enables the power-saving feature automatically when the power
 581cable is unplugged.  Thus, if you hear noises, suspect first the
 582power-saving.  See /sys/module/snd_hda_intel/parameters/power_save to
 583check the current value.  If it's non-zero, the feature is turned on.
 584
 585The recent kernel supports the runtime PM for the HD-audio controller
 586chip, too.  It means that the HD-audio controller is also powered up /
 587down dynamically.  The feature is enabled only for certain controller
 588chips like Intel LynxPoint.  You can enable/disable this feature
 589forcibly by setting `power_save_controller` option, which is also
 590available at /sys/module/snd_hda_intel/parameters directory.
 591
 592
 593Tracepoints
 594~~~~~~~~~~~
 595The hd-audio driver gives a few basic tracepoints.
 596`hda:hda_send_cmd` traces each CORB write while `hda:hda_get_response`
 597traces the response from RIRB (only when read from the codec driver).
 598`hda:hda_bus_reset` traces the bus-reset due to fatal error, etc,
 599`hda:hda_unsol_event` traces the unsolicited events, and
 600`hda:hda_power_down` and `hda:hda_power_up` trace the power down/up
 601via power-saving behavior.
 602
 603Enabling all tracepoints can be done like
 604------------------------------------------------------------------------
 605  # echo 1 > /sys/kernel/debug/tracing/events/hda/enable
 606------------------------------------------------------------------------
 607then after some commands, you can traces from
 608/sys/kernel/debug/tracing/trace file.  For example, when you want to
 609trace what codec command is sent, enable the tracepoint like:
 610------------------------------------------------------------------------
 611  # cat /sys/kernel/debug/tracing/trace
 612  # tracer: nop
 613  #
 614  #       TASK-PID    CPU#    TIMESTAMP  FUNCTION
 615  #          | |       |          |         |
 616         <...>-7807  [002] 105147.774889: hda_send_cmd: [0:0] val=e3a019
 617         <...>-7807  [002] 105147.774893: hda_send_cmd: [0:0] val=e39019
 618         <...>-7807  [002] 105147.999542: hda_send_cmd: [0:0] val=e3a01a
 619         <...>-7807  [002] 105147.999543: hda_send_cmd: [0:0] val=e3901a
 620         <...>-26764 [001] 349222.837143: hda_send_cmd: [0:0] val=e3a019
 621         <...>-26764 [001] 349222.837148: hda_send_cmd: [0:0] val=e39019
 622         <...>-26764 [001] 349223.058539: hda_send_cmd: [0:0] val=e3a01a
 623         <...>-26764 [001] 349223.058541: hda_send_cmd: [0:0] val=e3901a
 624------------------------------------------------------------------------
 625Here `[0:0]` indicates the card number and the codec address, and
 626`val` shows the value sent to the codec, respectively.  The value is
 627a packed value, and you can decode it via hda-decode-verb program
 628included in hda-emu package below.  For example, the value e3a019 is
 629to set the left output-amp value to 25.
 630------------------------------------------------------------------------
 631  % hda-decode-verb 0xe3a019
 632  raw value = 0x00e3a019
 633  cid = 0, nid = 0x0e, verb = 0x3a0, parm = 0x19
 634  raw value: verb = 0x3a0, parm = 0x19
 635  verbname = set_amp_gain_mute
 636  amp raw val = 0xa019
 637  output, left, idx=0, mute=0, val=25
 638------------------------------------------------------------------------
 639
 640
 641Development Tree
 642~~~~~~~~~~~~~~~~
 643The latest development codes for HD-audio are found on sound git tree:
 644
 645- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
 646
 647The master branch or for-next branches can be used as the main
 648development branches in general while the development for the current
 649and next kernels are found in for-linus and for-next branches,
 650respectively.
 651
 652If you are using the latest Linus tree, it'd be better to pull the
 653above GIT tree onto it.  If you are using the older kernels, an easy
 654way to try the latest ALSA code is to build from the snapshot
 655tarball.  There are daily tarballs and the latest snapshot tarball.
 656All can be built just like normal alsa-driver release packages, that
 657is, installed via the usual spells: configure, make and make
 658install(-modules).  See INSTALL in the package.  The snapshot tarballs
 659are found at:
 660
 661- ftp://ftp.suse.com/pub/people/tiwai/snapshot/
 662
 663
 664Sending a Bug Report
 665~~~~~~~~~~~~~~~~~~~~
 666If any model or module options don't work for your device, it's time
 667to send a bug report to the developers.  Give the following in your
 668bug report:
 669
 670- Hardware vendor, product and model names
 671- Kernel version (and ALSA-driver version if you built externally)
 672- `alsa-info.sh` output; run with `--no-upload` option.  See the
 673  section below about alsa-info
 674
 675If it's a regression, at best, send alsa-info outputs of both working
 676and non-working kernels.  This is really helpful because we can
 677compare the codec registers directly.
 678
 679Send a bug report either the followings:
 680
 681kernel-bugzilla::
 682  https://bugzilla.kernel.org/
 683alsa-devel ML::
 684  alsa-devel@alsa-project.org
 685
 686
 687DEBUG TOOLS
 688-----------
 689
 690This section describes some tools available for debugging HD-audio
 691problems.
 692
 693alsa-info
 694~~~~~~~~~
 695The script `alsa-info.sh` is a very useful tool to gather the audio
 696device information.  You can fetch the latest version from:
 697
 698- http://www.alsa-project.org/alsa-info.sh
 699
 700Run this script as root, and it will gather the important information
 701such as the module lists, module parameters, proc file contents
 702including the codec proc files, mixer outputs and the control
 703elements.  As default, it will store the information onto a web server
 704on alsa-project.org.  But, if you send a bug report, it'd be better to
 705run with `--no-upload` option, and attach the generated file.
 706
 707There are some other useful options.  See `--help` option output for
 708details.
 709
 710When a probe error occurs or when the driver obviously assigns a
 711mismatched model, it'd be helpful to load the driver with
 712`probe_only=1` option (at best after the cold reboot) and run
 713alsa-info at this state.  With this option, the driver won't configure
 714the mixer and PCM but just tries to probe the codec slot.  After
 715probing, the proc file is available, so you can get the raw codec
 716information before modified by the driver.  Of course, the driver
 717isn't usable with `probe_only=1`.  But you can continue the
 718configuration via hwdep sysfs file if hda-reconfig option is enabled.
 719Using `probe_only` mask 2 skips the reset of HDA codecs (use
 720`probe_only=3` as module option). The hwdep interface can be used
 721to determine the BIOS codec initialization.
 722
 723
 724hda-verb
 725~~~~~~~~
 726hda-verb is a tiny program that allows you to access the HD-audio
 727codec directly.  You can execute a raw HD-audio codec verb with this.
 728This program accesses the hwdep device, thus you need to enable the
 729kernel config `CONFIG_SND_HDA_HWDEP=y` beforehand.
 730
 731The hda-verb program takes four arguments: the hwdep device file, the
 732widget NID, the verb and the parameter.  When you access to the codec
 733on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first
 734argument, typically.  (However, the real path name depends on the
 735system.)
 736
 737The second parameter is the widget number-id to access.  The third
 738parameter can be either a hex/digit number or a string corresponding
 739to a verb.  Similarly, the last parameter is the value to write, or
 740can be a string for the parameter type.
 741
 742------------------------------------------------------------------------
 743  % hda-verb /dev/snd/hwC0D0 0x12 0x701 2
 744  nid = 0x12, verb = 0x701, param = 0x2
 745  value = 0x0
 746
 747  % hda-verb /dev/snd/hwC0D0 0x0 PARAMETERS VENDOR_ID
 748  nid = 0x0, verb = 0xf00, param = 0x0
 749  value = 0x10ec0262
 750
 751  % hda-verb /dev/snd/hwC0D0 2 set_a 0xb080
 752  nid = 0x2, verb = 0x300, param = 0xb080
 753  value = 0x0
 754------------------------------------------------------------------------
 755
 756Although you can issue any verbs with this program, the driver state
 757won't be always updated.  For example, the volume values are usually
 758cached in the driver, and thus changing the widget amp value directly
 759via hda-verb won't change the mixer value.
 760
 761The hda-verb program is included now in alsa-tools:
 762
 763- git://git.alsa-project.org/alsa-tools.git
 764
 765Also, the old stand-alone package is found in the ftp directory:
 766
 767- ftp://ftp.suse.com/pub/people/tiwai/misc/
 768
 769Also a git repository is available:
 770
 771- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-verb.git
 772
 773See README file in the tarball for more details about hda-verb
 774program.
 775
 776
 777hda-analyzer
 778~~~~~~~~~~~~
 779hda-analyzer provides a graphical interface to access the raw HD-audio
 780control, based on pyGTK2 binding.  It's a more powerful version of
 781hda-verb.  The program gives you an easy-to-use GUI stuff for showing
 782the widget information and adjusting the amp values, as well as the
 783proc-compatible output.
 784
 785The hda-analyzer:
 786
 787- http://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer
 788
 789is a part of alsa.git repository in alsa-project.org:
 790
 791- git://git.alsa-project.org/alsa.git
 792
 793Codecgraph
 794~~~~~~~~~~
 795Codecgraph is a utility program to generate a graph and visualizes the
 796codec-node connection of a codec chip.  It's especially useful when
 797you analyze or debug a codec without a proper datasheet.  The program
 798parses the given codec proc file and converts to SVG via graphiz
 799program.
 800
 801The tarball and GIT trees are found in the web page at:
 802
 803- http://helllabs.org/codecgraph/
 804
 805
 806hda-emu
 807~~~~~~~
 808hda-emu is an HD-audio emulator.  The main purpose of this program is
 809to debug an HD-audio codec without the real hardware.  Thus, it
 810doesn't emulate the behavior with the real audio I/O, but it just
 811dumps the codec register changes and the ALSA-driver internal changes
 812at probing and operating the HD-audio driver.
 813
 814The program requires a codec proc-file to simulate.  Get a proc file
 815for the target codec beforehand, or pick up an example codec from the
 816codec proc collections in the tarball.  Then, run the program with the
 817proc file, and the hda-emu program will start parsing the codec file
 818and simulates the HD-audio driver:
 819
 820------------------------------------------------------------------------
 821  % hda-emu codecs/stac9200-dell-d820-laptop
 822  # Parsing..
 823  hda_codec: Unknown model for STAC9200, using BIOS defaults
 824  hda_codec: pin nid 08 bios pin config 40c003fa
 825  ....
 826------------------------------------------------------------------------
 827
 828The program gives you only a very dumb command-line interface.  You
 829can get a proc-file dump at the current state, get a list of control
 830(mixer) elements, set/get the control element value, simulate the PCM
 831operation, the jack plugging simulation, etc.
 832
 833The package is found in:
 834
 835- ftp://ftp.suse.com/pub/people/tiwai/misc/
 836
 837A git repository is available:
 838
 839- git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/hda-emu.git
 840
 841See README file in the tarball for more details about hda-emu
 842program.
 843
 844
 845hda-jack-retask
 846~~~~~~~~~~~~~~~
 847hda-jack-retask is a user-friendly GUI program to manipulate the
 848HD-audio pin control for jack retasking.  If you have a problem about
 849the jack assignment, try this program and check whether you can get
 850useful results.  Once when you figure out the proper pin assignment,
 851it can be fixed either in the driver code statically or via passing a
 852firmware patch file (see "Early Patching" section).
 853
 854The program is included in alsa-tools now:
 855
 856- git://git.alsa-project.org/alsa-tools.git
 857
 858
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