[alsa-devel] [ALSA] ALSA Power Management, Drivers behaving unexpectedly after suspend/resume cycle

[Liam Girdwood]

On Fri, 2007-05-25 at 18:24 +0530, Nobin Mathew wrote:
> after resume when i do playback i am getting same number of DMA
> interrupt  as in the working case (after reboot).
> 

So, does aplay keeps playing until the end of your file or does it stop
after a short time due to no periods being transmitted to the codec (io
error) ? If it keeps playing then check the codec driver, it's possible
it hasn't resumed fully. 

> I am using aplay (/usr/share/sounds/alsa/Side_Right.wav)
> 
> But i am not getting any sound (3 underruns), my codec register
> contents and controller register contents are same.
> 

Codec drivers cache registers for faster IO, best make sure the cache is
refreshed at resume.

Also, what happens when you kill aplay and restart it after resume ?
Does audio play or does it still underrun with no audio ? If audio
works, then this suggests something in your resume path is missing.

Fwiw, I would expect to sometimes see an underrun at resume due to
resume being a busy period for most systems. 

Liam