HD-audio is the new standard on-board audio component on modern PCs after AC97. Although Linux has been supporting HD-audio since long time ago, there are often problems with new machines. A part of the problem is broken BIOS, and the rest is the driver implementation. This document explains the brief trouble-shooting and debugging methods for the HD-audio hardware.
The HD-audio component consists of two parts: the controller chip and the codec chips on the HD-audio bus. Linux provides a single driver for all controllers, snd-hda-intel. Although the driver name contains a word of a well-known hardware vendor, it’s not specific to it but for all controller chips by other companies. Since the HD-audio controllers are supposed to be compatible, the single snd-hda-driver should work in most cases. But, not surprisingly, there are known bugs and issues specific to each controller type. The snd-hda-intel driver has a bunch of workarounds for these as described below.
A controller may have multiple codecs. Usually you have one audio codec and optionally one modem codec. In theory, there might be multiple audio codecs, e.g. for analog and digital outputs, and the driver might not work properly because of conflict of mixer elements. This should be fixed in future if such hardware really exists.
The snd-hda-intel driver has several different codec parsers depending on the codec. It has a generic parser as a fallback, but this functionality is fairly limited until now. Instead of the generic parser, usually the codec-specific parser (coded in patch_*.c) is used for the codec-specific implementations. The details about the codec-specific problems are explained in the later sections.
If you are interested in the deep debugging of HD-audio, read the HD-audio specification at first. The specification is found on Intel’s web page, for example:
The most common problem of the controller is the inaccurate DMA
pointer reporting. The DMA pointer for playback and capture can be
read in two ways, either via a LPIB register or via a position-buffer
map. As default the driver tries to read from the io-mapped
position-buffer, and falls back to LPIB if the position-buffer appears
dead. However, this detection isn’t perfect on some devices. In such
a case, you can change the default method via position_fix option.
position_fix=1 means to use LPIB method explicitly.
position_fix=2 means to use the position-buffer. 0 is the default
value, the automatic check and fallback to LPIB as described in the
above. If you get a problem of repeated sounds, this option might
help.
In addition to that, every controller is known to be broken regarding
the wake-up timing. It wakes up a few samples before actually
processing the data on the buffer. This caused a lot of problems, for
example, with ALSA dmix or JACK. Since 2.6.27 kernel, the driver puts
an artificial delay to the wake up timing. This delay is controlled
via bdl_pos_adj option.
When bdl_pos_adj is a negative value (as default), it’s assigned to
an appropriate value depending on the controller chip. For Intel
chips, it’d be 1 while it’d be 32 for others. Usually this works.
Only in case it doesn’t work and you get warning messages, you should
change this parameter to other values.
A less often but a more severe problem is the codec probing. When BIOS reports the available codec slots wrongly, the driver gets confused and tries to access the non-existing codec slot. This often results in the total screw-up, and destructs the further communication with the codec chips. The symptom appears usually as error messages like:
hda_intel: azx_get_response timeout, switching to polling mode:
last cmd=0x12345678
hda_intel: azx_get_response timeout, switching to single_cmd mode:
last cmd=0x12345678The first line is a warning, and this is usually relatively harmless. It means that the codec response isn’t notified via an IRQ. The driver uses explicit polling method to read the response. It gives very slight CPU overhead, but you’d unlikely notice it.
The second line is, however, a fatal error. If this happens, usually it means that something is really wrong. Most likely you are accessing a non-existing codec slot.
Thus, if the second error message appears, try to narrow the probed
codec slots via probe_mask option. It’s a bitmask, and each bit
corresponds to the codec slot. For example, to probe only the first
slot, pass probe_mask=1. For the first and the third slots, pass
probe_mask=5 (where 5 = 1 | 4), and so on.
Since 2.6.29 kernel, the driver has a more robust probing method, so this error might happen rarely, though.
On a machine with a broken BIOS, sometimes you need to force the
driver to probe the codec slots the hardware doesn’t report for use.
In such a case, turn the bit 8 (0x100) of probe_mask option on.
Then the rest 8 bits are passed as the codec slots to probe
unconditionally. For example, probe_mask=0x103 will force to probe
the codec slots 0 and 1 no matter what the hardware reports.
The most common problem regarding the HD-audio driver is the unsupported codec features or the mismatched device configuration. Most of codec-specific code has several preset models, either to override the BIOS setup or to provide more comprehensive features.
The driver checks PCI SSID and looks through the static configuration table until any matching entry is found. If you have a new machine, you may see a message like below:
hda_codec: ALC880: BIOS auto-probing.
Meanwhile, in the earlier versions, you would see a message like:
hda_codec: Unknown model for ALC880, trying auto-probe from BIOS...
Even if you see such a message, DON’T PANIC. Take a deep breath and keep your towel. First of all, it’s an informational message, no warning, no error. This means that the PCI SSID of your device isn’t listed in the known preset model (white-)list. But, this doesn’t mean that the driver is broken. Many codec-drivers provide the automatic configuration mechanism based on the BIOS setup.
The HD-audio codec has usually "pin" widgets, and BIOS sets the default configuration of each pin, which indicates the location, the connection type, the jack color, etc. The HD-audio driver can guess the right connection judging from these default configuration values. However — some codec-support codes, such as patch_analog.c, don’t support the automatic probing (yet as of 2.6.28). And, BIOS is often, yes, pretty often broken. It sets up wrong values and screws up the driver.
The preset model is provided basically to overcome such a situation.
When the matching preset model is found in the white-list, the driver
assumes the static configuration of that preset and builds the mixer
elements and PCM streams based on the static information. Thus, if
you have a newer machine with a slightly different PCI SSID from the
existing one, you may have a good chance to re-use the same model.
You can pass the model option to specify the preset model instead of
PCI SSID look-up.
What model option values are available depends on the codec chip.
Check your codec chip from the codec proc file (see "Codec Proc-File"
section below). It will show the vendor/product name of your codec
chip. Then, see Documentation/sound/alsa/HD-Audio-Models.txt file,
the section of HD-audio driver. You can find a list of codecs
and model options belonging to each codec. For example, for Realtek
ALC262 codec chip, pass model=ultra for devices that are compatible
with Samsung Q1 Ultra.
Thus, the first thing you can do for any brand-new, unsupported and
non-working HD-audio hardware is to check HD-audio codec and several
different model option values. If you have any luck, some of them
might suit with your device well.
Some codecs such as ALC880 have a special model option model=test.
This configures the driver to provide as many mixer controls as
possible for every single pin feature except for the unsolicited
events (and maybe some other specials). Adjust each mixer element and
try the I/O in the way of trial-and-error until figuring out the whole
I/O pin mappings.
Note that model=generic has a special meaning. It means to use the
generic parser regardless of the codec. Usually the codec-specific
parser is much better than the generic parser (as now). Thus this
option is more about the debugging purpose.
One of the most frequent (and obvious) bugs with HD-audio is the silent output from either or both of a built-in speaker and a headphone jack. In general, you should try a headphone output at first. A speaker output often requires more additional controls like the external amplifier bits. Thus a headphone output has a slightly better chance.
Before making a bug report, double-check whether the mixer is set up correctly. The recent version of snd-hda-intel driver provides mostly "Master" volume control as well as "Front" volume (where Front indicates the front-channels). In addition, there can be individual "Headphone" and "Speaker" controls.
Ditto for the speaker output. There can be "External Amplifier" switch on some codecs. Turn on this if present.
Another related problem is the automatic mute of speaker output by headphone plugging. This feature is implemented in most cases, but not on every preset model or codec-support code.
In anyway, try a different model option if you have such a problem. Some other models may match better and give you more matching functionality. If none of the available models works, send a bug report. See the bug report section for details.
If you are masochistic enough to debug the driver problem, note the following:
The capture problems are often because of missing setups of mixers. Thus, before submitting a bug report, make sure that you set up the mixer correctly. For example, both "Capture Volume" and "Capture Switch" have to be set properly in addition to the right "Capture Source" or "Input Source" selection. Some devices have "Mic Boost" volume or switch.
When the PCM device is opened via "default" PCM (without pulse-audio plugin), you’ll likely have "Digital Capture Volume" control as well. This is provided for the extra gain/attenuation of the signal in software, especially for the inputs without the hardware volume control such as digital microphones. Unless really needed, this should be set to exactly 50%, corresponding to 0dB — neither extra gain nor attenuation. When you use "hw" PCM, i.e., a raw access PCM, this control will have no influence, though.
It’s known that some codecs / devices have fairly bad analog circuits, and the recorded sound contains a certain DC-offset. This is no bug of the driver.
Most of modern laptops have no analog CD-input connection. Thus, the recording from CD input won’t work in many cases although the driver provides it as the capture source. Use CDDA instead.
The automatic switching of the built-in and external mic per plugging is implemented on some codec models but not on every model. Partly because of my laziness but mostly lack of testers. Feel free to submit the improvement patch to the author.
If no model option gives you a better result, and you are a tough guy to fight against evil, try debugging via hitting the raw HD-audio codec verbs to the device. Some tools are available: hda-emu and hda-analyzer. The detailed description is found in the sections below. You’d need to enable hwdep for using these tools. See "Kernel Configuration" section.
In general, I recommend you to enable the sound debug option,
CONFIG_SND_DEBUG=y, no matter whether you are debugging or not.
This enables snd_printd() macro and others, and you’ll get additional
kernel messages at probing.
In addition, you can enable CONFIG_SND_DEBUG_VERBOSE=y. But this
will give you far more messages. Thus turn this on only when you are
sure to want it.
Don’t forget to turn on the appropriate CONFIG_SND_HDA_CODEC_*
options. Note that each of them corresponds to the codec chip, not
the controller chip. Thus, even if lspci shows the Nvidia controller,
you may need to choose the option for other vendors. If you are
unsure, just select all yes.
CONFIG_SND_HDA_HWDEP is a useful option for debugging the driver.
When this is enabled, the driver creates hardware-dependent devices
(one per each codec), and you have a raw access to the device via
these device files. For example, hwC0D2 will be created for the
codec slot #2 of the first card (#0). For debug-tools such as
hda-verb and hda-analyzer, the hwdep device has to be enabled.
Thus, it’d be better to turn this on always.
CONFIG_SND_HDA_RECONFIG is a new option, and this depends on the
hwdep option above. When enabled, you’ll have some sysfs files under
the corresponding hwdep directory. See "HD-audio reconfiguration"
section below.
CONFIG_SND_HDA_POWER_SAVE option enables the power-saving feature.
See "Power-saving" section below.
The codec proc-file is a treasure-chest for debugging HD-audio. It shows most of useful information of each codec widget.
The proc file is located in /proc/asound/card*/codec#*, one file per each codec slot. You can know the codec vendor, product id and names, the type of each widget, capabilities and so on. This file, however, doesn’t show the jack sensing state, so far. This is because the jack-sensing might be depending on the trigger state.
This file will be picked up by the debug tools, and also it can be fed to the emulator as the primary codec information. See the debug tools section below.
This proc file can be also used to check whether the generic parser is used. When the generic parser is used, the vendor/product ID name will appear as "Realtek ID 0262", instead of "Realtek ALC262".
This is an experimental feature to allow you re-configure the HD-audio codec dynamically without reloading the driver. The following sysfs files are available under each codec-hwdep device directory (e.g. /sys/class/sound/hwC0D0):
model option. Can be changed by writing
to this file.
key = value. For example, passing hp_detect = yes
to IDT/STAC codec parser will result in the disablement of the
headphone detection.
For example, when you want to change the pin default configuration value of the pin widget 0x14 to 0x9993013f, and let the driver re-configure based on that state, run like below:
# echo 0x14 0x9993013f > /sys/class/sound/hwC0D0/user_pin_configs # echo 1 > /sys/class/sound/hwC0D0/reconfig
When CONFIG_SND_HDA_PATCH_LOADER=y is set, you can pass a "patch" as a firmware file for modifying the HD-audio setup before initializing the codec. This can work basically like the reconfiguration via sysfs in the above, but it does it before the first codec configuration.
A patch file is a plain text file which looks like below:
[codec] 0x12345678 0xabcd1234 2 [model] auto [pincfg] 0x12 0x411111f0 [verb] 0x20 0x500 0x03 0x20 0x400 0xff [hint] hp_detect = yes
The file needs to have a line [codec]. The next line should contain
three numbers indicating the codec vendor-id (0x12345678 in the
example), the codec subsystem-id (0xabcd1234) and the address (2) of
the codec. The rest patch entries are applied to this specified codec
until another codec entry is given.
The [model] line allows to change the model name of the each codec.
In the example above, it will be changed to model=auto.
Note that this overrides the module option.
After the [pincfg] line, the contents are parsed as the initial
default pin-configurations just like user_pin_configs sysfs above.
The values can be shown in user_pin_configs sysfs file, too.
Similarly, the lines after [verb] are parsed as init_verbs
sysfs entries, and the lines after [hint] are parsed as hints
sysfs entries, respectively.
The hd-audio driver reads the file via request_firmware(). Thus,
a patch file has to be located on the appropriate firmware path,
typically, /lib/firmware. For example, when you pass the option
patch=hda-init.fw, the file /lib/firmware/hda-init-fw must be
present.
The patch module option is specific to each card instance, and you need to give one file name for each instance, separated by commas. For example, if you have two cards, one for an on-board analog and one for an HDMI video board, you may pass patch option like below:
options snd-hda-intel patch=on-board-patch,hdmi-patch
The power-saving is a kind of auto-suspend of the device. When the
device is inactive for a certain time, the device is automatically
turned off to save the power. The time to go down is specified via
power_save module option, and this option can be changed dynamically
via sysfs.
The power-saving won’t work when the analog loopback is enabled on some codecs. Make sure that you mute all unneeded signal routes when you want the power-saving.
The power-saving feature might cause audible click noises at each power-down/up depending on the device. Some of them might be solvable, but some are hard, I’m afraid. Some distros such as openSUSE enables the power-saving feature automatically when the power cable is unplugged. Thus, if you hear noises, suspect first the power-saving. See /sys/module/snd_hda_intel/parameters/power_save to check the current value. If it’s non-zero, the feature is turned on.
The latest development codes for HD-audio are found on sound git tree:
The master branch or for-next branches can be used as the main development branches in general while the HD-audio specific patches are committed in topic/hda branch.
If you are using the latest Linus tree, it’d be better to pull the above GIT tree onto it. If you are using the older kernels, an easy way to try the latest ALSA code is to build from the snapshot tarball. There are daily tarballs and the latest snapshot tarball. All can be built just like normal alsa-driver release packages, that is, installed via the usual spells: configure, make and make install(-modules). See INSTALL in the package. The snapshot tarballs are found at:
If any model or module options don’t work for your device, it’s time to send a bug report to the developers. Give the following in your bug report:
alsa-info.sh output; run with --no-upload option. See the
section below about alsa-info
If it’s a regression, at best, send alsa-info outputs of both working and non-working kernels. This is really helpful because we can compare the codec registers directly.
Send a bug report either the followings:
This section describes some tools available for debugging HD-audio problems.
The script alsa-info.sh is a very useful tool to gather the audio
device information. You can fetch the latest version from:
Run this script as root, and it will gather the important information
such as the module lists, module parameters, proc file contents
including the codec proc files, mixer outputs and the control
elements. As default, it will store the information onto a web server
on alsa-project.org. But, if you send a bug report, it’d be better to
run with --no-upload option, and attach the generated file.
There are some other useful options. See --help option output for
details.
When a probe error occurs or when the driver obviously assigns a
mismatched model, it’d be helpful to load the driver with
probe_only=1 option (at best after the cold reboot) and run
alsa-info at this state. With this option, the driver won’t configure
the mixer and PCM but just tries to probe the codec slot. After
probing, the proc file is available, so you can get the raw codec
information before modified by the driver. Of course, the driver
isn’t usable with probe_only=1. But you can continue the
configuration via hwdep sysfs file if hda-reconfig option is enabled.
hda-verb is a tiny program that allows you to access the HD-audio
codec directly. You can execute a raw HD-audio codec verb with this.
This program accesses the hwdep device, thus you need to enable the
kernel config CONFIG_SND_HDA_HWDEP=y beforehand.
The hda-verb program takes four arguments: the hwdep device file, the widget NID, the verb and the parameter. When you access to the codec on the slot 2 of the card 0, pass /dev/snd/hwC0D2 to the first argument, typically. (However, the real path name depends on the system.)
The second parameter is the widget number-id to access. The third parameter can be either a hex/digit number or a string corresponding to a verb. Similarly, the last parameter is the value to write, or can be a string for the parameter type.
% hda-verb /dev/snd/hwC0D0 0x12 0x701 2 nid = 0x12, verb = 0x701, param = 0x2 value = 0x0 % hda-verb /dev/snd/hwC0D0 0x0 PARAMETERS VENDOR_ID nid = 0x0, verb = 0xf00, param = 0x0 value = 0x10ec0262 % hda-verb /dev/snd/hwC0D0 2 set_a 0xb080 nid = 0x2, verb = 0x300, param = 0xb080 value = 0x0
Although you can issue any verbs with this program, the driver state won’t be always updated. For example, the volume values are usually cached in the driver, and thus changing the widget amp value directly via hda-verb won’t change the mixer value.
The hda-verb program is found in the ftp directory:
Also a git repository is available:
See README file in the tarball for more details about hda-verb program.
hda-analyzer provides a graphical interface to access the raw HD-audio control, based on pyGTK2 binding. It’s a more powerful version of hda-verb. The program gives you an easy-to-use GUI stuff for showing the widget information and adjusting the amp values, as well as the proc-compatible output.
The hda-analyzer is a part of alsa.git repository in alsa-project.org:
Codecgraph is a utility program to generate a graph and visualizes the codec-node connection of a codec chip. It’s especially useful when you analyze or debug a codec without a proper datasheet. The program parses the given codec proc file and converts to SVG via graphiz program.
The tarball and GIT trees are found in the web page at:
hda-emu is an HD-audio emulator. The main purpose of this program is to debug an HD-audio codec without the real hardware. Thus, it doesn’t emulate the behavior with the real audio I/O, but it just dumps the codec register changes and the ALSA-driver internal changes at probing and operating the HD-audio driver.
The program requires a codec proc-file to simulate. Get a proc file for the target codec beforehand, or pick up an example codec from the codec proc collections in the tarball. Then, run the program with the proc file, and the hda-emu program will start parsing the codec file and simulates the HD-audio driver:
% hda-emu codecs/stac9200-dell-d820-laptop # Parsing.. hda_codec: Unknown model for STAC9200, using BIOS defaults hda_codec: pin nid 08 bios pin config 40c003fa ....
The program gives you only a very dumb command-line interface. You can get a proc-file dump at the current state, get a list of control (mixer) elements, set/get the control element value, simulate the PCM operation, the jack plugging simulation, etc.
The package is found in:
A git repository is available:
See README file in the tarball for more details about hda-emu program.