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

Liam Girdwood lg at opensource.wolfsonmicro.com
Fri May 25 15:19:09 CEST 2007

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. 


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