Commit 056c1ebf authored by Takashi Iwai's avatar Takashi Iwai
Browse files

Merge branch 'topic/pcm-jiffies-check' into for-linus

* topic/pcm-jiffies-check:
  ALSA: pcm - Update document about xrun_debug proc file
parents be914cf9 4f64e150
...@@ -88,26 +88,34 @@ card*/pcm*/info ...@@ -88,26 +88,34 @@ card*/pcm*/info
substreams, etc. substreams, etc.
card*/pcm*/xrun_debug card*/pcm*/xrun_debug
This file appears when CONFIG_SND_DEBUG=y. This file appears when CONFIG_SND_DEBUG=y and
This shows the status of xrun (= buffer overrun/xrun) debug of CONFIG_PCM_XRUN_DEBUG=y.
ALSA PCM middle layer, as an integer from 0 to 2. The value This shows the status of xrun (= buffer overrun/xrun) and
can be changed by writing to this file, such as invalid PCM position debug/check of ALSA PCM middle layer.
It takes an integer value, can be changed by writing to this
# cat 2 > /proc/asound/card0/pcm0p/xrun_debug file, such as
When this value is greater than 0, the driver will show the # cat 5 > /proc/asound/card0/pcm0p/xrun_debug
messages to kernel log when an xrun is detected. The debug
message is shown also when the invalid H/W pointer is detected The value consists of the following bit flags:
at the update of periods (usually called from the interrupt 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). handler).
When this value is greater than 1, the driver will show the When the bit 1 is set, the driver will show the stack trace
stack trace additionally. This may help the debugging. additionally. This may help the debugging.
Since 2.6.30, this option also enables the hwptr check using Since 2.6.30, this option can enable the hwptr check using
jiffies. This detects spontaneous invalid pointer callback jiffies. This detects spontaneous invalid pointer callback
values, but can be lead to too much corrections for a (mostly values, but can be lead to too much corrections for a (mostly
buggy) hardware that doesn't give smooth pointer updates. buggy) hardware that doesn't give smooth pointer updates.
This feature is enabled via the bit 2.
card*/pcm*/sub*/info card*/pcm*/sub*/info
The general information of this PCM sub-stream. The general information of this PCM sub-stream.
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