239 lines
6.6 KiB
ReStructuredText
239 lines
6.6 KiB
ReStructuredText
==========================
|
|
Proc Files of ALSA Drivers
|
|
==========================
|
|
|
|
Takashi Iwai <tiwai@suse.de>
|
|
|
|
General
|
|
=======
|
|
|
|
ALSA has its own proc tree, /proc/asound. Many useful information are
|
|
found in this tree. When you encounter a problem and need debugging,
|
|
check the files listed in the following sections.
|
|
|
|
Each card has its subtree cardX, where X is from 0 to 7. The
|
|
card-specific files are stored in the ``card*`` subdirectories.
|
|
|
|
|
|
Global Information
|
|
==================
|
|
|
|
cards
|
|
Shows the list of currently configured ALSA drivers,
|
|
index, the id string, short and long descriptions.
|
|
|
|
version
|
|
Shows the version string and compile date.
|
|
|
|
modules
|
|
Lists the module of each card
|
|
|
|
devices
|
|
Lists the ALSA native device mappings.
|
|
|
|
meminfo
|
|
Shows the status of allocated pages via ALSA drivers.
|
|
Appears only when ``CONFIG_SND_DEBUG=y``.
|
|
|
|
hwdep
|
|
Lists the currently available hwdep devices in format of
|
|
``<card>-<device>: <name>``
|
|
|
|
pcm
|
|
Lists the currently available PCM devices in format of
|
|
``<card>-<device>: <id>: <name> : <sub-streams>``
|
|
|
|
timer
|
|
Lists the currently available timer devices
|
|
|
|
|
|
oss/devices
|
|
Lists the OSS device mappings.
|
|
|
|
oss/sndstat
|
|
Provides the output compatible with /dev/sndstat.
|
|
You can symlink this to /dev/sndstat.
|
|
|
|
|
|
Card Specific Files
|
|
===================
|
|
|
|
The card-specific files are found in ``/proc/asound/card*`` directories.
|
|
Some drivers (e.g. cmipci) have their own proc entries for the
|
|
register dump, etc (e.g. ``/proc/asound/card*/cmipci`` shows the register
|
|
dump). These files would be really helpful for debugging.
|
|
|
|
When PCM devices are available on this card, you can see directories
|
|
like pcm0p or pcm1c. They hold the PCM information for each PCM
|
|
stream. The number after ``pcm`` is the PCM device number from 0, and
|
|
the last ``p`` or ``c`` means playback or capture direction. The files in
|
|
this subtree is described later.
|
|
|
|
The status of MIDI I/O is found in ``midi*`` files. It shows the device
|
|
name and the received/transmitted bytes through the MIDI device.
|
|
|
|
When the card is equipped with AC97 codecs, there are ``codec97#*``
|
|
subdirectories (described later).
|
|
|
|
When the OSS mixer emulation is enabled (and the module is loaded),
|
|
oss_mixer file appears here, too. This shows the current mapping of
|
|
OSS mixer elements to the ALSA control elements. You can change the
|
|
mapping by writing to this device. Read OSS-Emulation.txt for
|
|
details.
|
|
|
|
|
|
PCM Proc Files
|
|
==============
|
|
|
|
``card*/pcm*/info``
|
|
The general information of this PCM device: card #, device #,
|
|
substreams, etc.
|
|
|
|
``card*/pcm*/xrun_debug``
|
|
This file appears when ``CONFIG_SND_DEBUG=y`` and
|
|
``CONFIG_PCM_XRUN_DEBUG=y``.
|
|
This shows the status of xrun (= buffer overrun/xrun) and
|
|
invalid PCM position debug/check of ALSA PCM middle layer.
|
|
It takes an integer value, can be changed by writing to this
|
|
file, such as::
|
|
|
|
# echo 5 > /proc/asound/card0/pcm0p/xrun_debug
|
|
|
|
The value consists of the following bit flags:
|
|
|
|
* bit 0 = Enable XRUN/jiffies debug messages
|
|
* bit 1 = Show stack trace at XRUN / jiffies check
|
|
* bit 2 = Enable additional jiffies check
|
|
|
|
When the bit 0 is set, the driver will show the messages to
|
|
kernel log when an xrun is detected. The debug message is
|
|
shown also when the invalid H/W pointer is detected at the
|
|
update of periods (usually called from the interrupt
|
|
handler).
|
|
|
|
When the bit 1 is set, the driver will show the stack trace
|
|
additionally. This may help the debugging.
|
|
|
|
Since 2.6.30, this option can enable the hwptr check using
|
|
jiffies. This detects spontaneous invalid pointer callback
|
|
values, but can be lead to too much corrections for a (mostly
|
|
buggy) hardware that doesn't give smooth pointer updates.
|
|
This feature is enabled via the bit 2.
|
|
|
|
``card*/pcm*/sub*/info``
|
|
The general information of this PCM sub-stream.
|
|
|
|
``card*/pcm*/sub*/status``
|
|
The current status of this PCM sub-stream, elapsed time,
|
|
H/W position, etc.
|
|
|
|
``card*/pcm*/sub*/hw_params``
|
|
The hardware parameters set for this sub-stream.
|
|
|
|
``card*/pcm*/sub*/sw_params``
|
|
The soft parameters set for this sub-stream.
|
|
|
|
``card*/pcm*/sub*/prealloc``
|
|
The buffer pre-allocation information.
|
|
|
|
``card*/pcm*/sub*/xrun_injection``
|
|
Triggers an XRUN to the running stream when any value is
|
|
written to this proc file. Used for fault injection.
|
|
This entry is write-only.
|
|
|
|
AC97 Codec Information
|
|
======================
|
|
|
|
``card*/codec97#*/ac97#?-?``
|
|
Shows the general information of this AC97 codec chip, such as
|
|
name, capabilities, set up.
|
|
|
|
``card*/codec97#0/ac97#?-?+regs``
|
|
Shows the AC97 register dump. Useful for debugging.
|
|
|
|
When CONFIG_SND_DEBUG is enabled, you can write to this file for
|
|
changing an AC97 register directly. Pass two hex numbers.
|
|
For example,
|
|
|
|
::
|
|
|
|
# echo 02 9f1f > /proc/asound/card0/codec97#0/ac97#0-0+regs
|
|
|
|
|
|
USB Audio Streams
|
|
=================
|
|
|
|
``card*/stream*``
|
|
Shows the assignment and the current status of each audio stream
|
|
of the given card. This information is very useful for debugging.
|
|
|
|
|
|
HD-Audio Codecs
|
|
===============
|
|
|
|
``card*/codec#*``
|
|
Shows the general codec information and the attribute of each
|
|
widget node.
|
|
|
|
``card*/eld#*``
|
|
Available for HDMI or DisplayPort interfaces.
|
|
Shows ELD(EDID Like Data) info retrieved from the attached HDMI sink,
|
|
and describes its audio capabilities and configurations.
|
|
|
|
Some ELD fields may be modified by doing ``echo name hex_value > eld#*``.
|
|
Only do this if you are sure the HDMI sink provided value is wrong.
|
|
And if that makes your HDMI audio work, please report to us so that we
|
|
can fix it in future kernel releases.
|
|
|
|
|
|
Sequencer Information
|
|
=====================
|
|
|
|
seq/drivers
|
|
Lists the currently available ALSA sequencer drivers.
|
|
|
|
seq/clients
|
|
Shows the list of currently available sequencer clients and
|
|
ports. The connection status and the running status are shown
|
|
in this file, too.
|
|
|
|
seq/queues
|
|
Lists the currently allocated/running sequencer queues.
|
|
|
|
seq/timer
|
|
Lists the currently allocated/running sequencer timers.
|
|
|
|
seq/oss
|
|
Lists the OSS-compatible sequencer stuffs.
|
|
|
|
|
|
Help For Debugging?
|
|
===================
|
|
|
|
When the problem is related with PCM, first try to turn on xrun_debug
|
|
mode. This will give you the kernel messages when and where xrun
|
|
happened.
|
|
|
|
If it's really a bug, report it with the following information:
|
|
|
|
- the name of the driver/card, show in ``/proc/asound/cards``
|
|
- the register dump, if available (e.g. ``card*/cmipci``)
|
|
|
|
when it's a PCM problem,
|
|
|
|
- set-up of PCM, shown in hw_parms, sw_params, and status in the PCM
|
|
sub-stream directory
|
|
|
|
when it's a mixer problem,
|
|
|
|
- AC97 proc files, ``codec97#*/*`` files
|
|
|
|
for USB audio/midi,
|
|
|
|
- output of ``lsusb -v``
|
|
- ``stream*`` files in card directory
|
|
|
|
|
|
The ALSA bug-tracking system is found at:
|
|
https://bugtrack.alsa-project.org/alsa-bug/
|