ALSA: pcm - Add logging of hwptr updates and interrupt updates

Added the logging functionality to xrun_debug to record the hwptr
updates via snd_pcm_update_hw_ptr() and snd_pcm_update_hwptr_interrupt(),
corresponding to 16 and 8, respectively.

For example,
	# echo 9 > /proc/asound/card0/pcm0p/xrun_debug
will record the position and other parameters at each period interrupt
together with the normal XRUN debugging.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/sound/alsa/Procfile.txt b/Documentation/sound/alsa/Procfile.txt
index 381908d8ca42..719a819f8cc2 100644
--- a/Documentation/sound/alsa/Procfile.txt
+++ b/Documentation/sound/alsa/Procfile.txt
@@ -101,6 +101,8 @@ card*/pcm*/xrun_debug
           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()
 
         When the bit 0 is set, the driver will show the messages to
         kernel log when an xrun is detected.  The debug message is
@@ -117,6 +119,9 @@ card*/pcm*/xrun_debug
         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.
+
 card*/pcm*/sub*/info
         The general information of this PCM sub-stream.