diff options
Diffstat (limited to 'Documentation/sound/alsa/Procfile.txt')
| -rw-r--r-- | Documentation/sound/alsa/Procfile.txt | 86 |
1 files changed, 69 insertions, 17 deletions
diff --git a/Documentation/sound/alsa/Procfile.txt b/Documentation/sound/alsa/Procfile.txt index 25c5d648aef..7fcd1ad96fc 100644 --- a/Documentation/sound/alsa/Procfile.txt +++ b/Documentation/sound/alsa/Procfile.txt @@ -71,7 +71,7 @@ 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 (desribed later). +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 @@ -88,21 +88,47 @@ card*/pcm*/info substreams, etc. card*/pcm*/xrun_debug - This file appears when CONFIG_SND_DEBUG=y. - This shows the status of xrun (= buffer overrun/xrun) debug of - ALSA PCM middle layer, as an integer from 0 to 2. The value - can be changed by writing to this file, such as + 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 + bit 3 = Log hwptr update at each period interrupt + bit 4 = Log hwptr update at each snd_pcm_update_hw_ptr() + bit 5 = Show last 10 positions on error + bit 6 = Do above only once + + 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). - # cat 2 > /proc/asound/card0/pcm0p/xrun_debug + When the bit 1 is set, the driver will show the stack trace + additionally. This may help the debugging. - When this value is greater than 0, 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). + 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. + + Bits 3 and 4 are for logging the hwptr records. Note that + these will give flood of kernel messages. - When this value is greater than 1, the driver will show the - stack trace additionally. This may help the debugging. + When bit 5 is set, the driver logs the last 10 xrun errors and + the proc file shows each jiffies, position, period_size, + buffer_size, old_hw_ptr, and hw_ptr_base values. + + When bit 6 is set, the full xrun log is shown only once. card*/pcm*/sub*/info The general information of this PCM sub-stream. @@ -138,6 +164,32 @@ card*/codec97#0/ac97#?-?+regs # 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 --------------------- @@ -145,12 +197,12 @@ seq/drivers Lists the currently available ALSA sequencer drivers. seq/clients - Shows the list of currently available sequencer clinets and + 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 sequener queues. + Lists the currently allocated/running sequencer queues. seq/timer Lists the currently allocated/running sequencer timers. @@ -166,10 +218,10 @@ 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 +If it's really a bug, report it with the following information: - the name of the driver/card, show in /proc/asound/cards - - the reigster dump, if available (e.g. card*/cmipci) + - the register dump, if available (e.g. card*/cmipci) when it's a PCM problem, |