Hi Dave!

> Thanks so much for fixing this! Would you mind telling me how the
dmasound_awacs.c fix came to your attention? I was completely stuck when
I tried looking into this earlier, maybe I'll learn something :-)

Pure luck :-) I am also completely new to kernel hacking... I read your
message about the xfer_status in snd_pmac_pcm_update, added some
debugging printks in my sources in this function, then found out that
the DEAD bit is set as soon as the sound dies. Since I knew that the old
OSS driver was still working with newer kernels (at least 2.6.20, I was
not able to use it in 2.6.22 anymore), I peeked into the sources there
and spotted the DEAD DMA transfer handling in it.

> I'm also wondering whether this counts as a fix or a workaround. It's
somewhat weird that we're now seeing the same problem in the ALSA driver
as OSS used to have--but for years these DEAD DMA transfers never showed
up in ALSA.

Agreed, maybe it's just a workaround. Maybe this patch from Ben
Herrenschmidt is causing some troubles with DMA that haven't been there
before? Looking at Ben's patch, there is some stuff related to DMA and
IDE (which also uses DMA) in it... have you already been in contact with
Ben Herrenschmidt because of this?

-- 
No sound in linux-image-2.6.20-8-powerpc G4 
https://bugs.launchpad.net/bugs/87652
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