[alsa-devel] Problem with snd_hda_intel from 05-27-2010 snapshot

[Jaroslav Kysela]

On Wed, 26 May 2010, VDR User wrote:

>> Hi.  I had been mostly successfully using the snd_hda_intel driver
>> from the stable kernel 2.6.34 for HDMI audio with my Nvidia GT220
>> video card.  In an attempt to see if any recent changes to
>> snd_hda_intel would fix a problem I've been having with "pcm_hw.c:
>> snd_pcm_hw_delay() SNDRV_PCM_IOCTL_DELAY failed" I decided to download
>> the latest snapshot.  Unfortunately with these drivers I have no
>> audio.  All my settings, and everything have remained the same.  The
>> only noticable difference I've found is
>> /sys/module/snd_hda_intel/parameters/probe_only is 0,0,0,0,0,0,0,0 in
>> the snapshot drivers, and N,N,N,N,N,N,N,N in the 2.6.34 kernel drivers
>> (which are compiled into the kernel).
>
> As a followup, I tried each snapshot going backwards from 05-27-2010
> to discover where the breakage occured.  The last working snapshot is
> 05-11-2010, it breaks at 05-12-2010.  After making a diff of the
> sound/pci/hda/ dir, I've discovered that the offending patch is:
>
> author	Jaroslav Kysela <perex at perex.cz>
> 	 Tue, 11 May 2010 08:21:46 +0000 (10:21 +0200)
> committer	Jaroslav Kysela <perex at perex.cz>
> 	 Tue, 11 May 2010 08:25:50 +0000 (10:25 +0200)
> commit	432f57d106e6d5c69fce74c888de32c6df347494
> tree	536120322429edb82d672547595d8dba7ac10b5e	tree | snapshot
> parent	533538fe6243d87b68db6942b1c7a1acb9fe504d	commit | diff
>
> [ALSA] snd-hda-intel: use WALLCLK register to check for early irqs
>
> Use 24Mhz WALLCLK register to ignore too early interrupts and
> wrong interrupt status. The bad timing confuses the higher ALSA
> layer and causes audio skipping. More information about behaviour
> and debugging can be found in kernel bz#15912.
>
> https://bugzilla.kernel.org/show_bug.cgi?id=15912

Check any suspicious lines in /var/log/messages and follow proc xrun_debug 
settings noted in bug above. I need at least 20 first lines after the 
playback is started.

Also, use 'aplay -Dplughw:0' from the alsa-utils package to trigger 
the playback.

 					Jaroslav

-----
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.