How to track down "play interrupt timeout"?

[Sascha Klauder]

Hi all,

 I've recently updated my somewhat aged 6.2-STABLE (from March 2007)
on my HP nx9005 laptop to a recent -STABLE, which somehow broke sound
support.  Before, I never had any trouble with sound since 5.2-RELEASE.
Went straight on to 7-CURRENT (just a few days before the BETA branch),
but the problem persists.

 It's an Acer Labs M5451 card (snd_t4dwave driver). Problem: playback
stops after a few seconds with
 pcm0:play:dsp0.p1: play interrupt timeout, channel dead

Verbose dmesg available here:
 http://demira.shopkeeper.de/~sascha/nx9005/misc/dmesg-7-verbose

  My CVS-fu isn't that good yet to track down all the files associated
with each sound code change that I'd need to check out to single out a
specific commit, so where would be a good start?

Cheers,
-sascha