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

[Takashi Iwai]

At Fri, 25 May 2007 11:27:10 +0530,
Nobin Mathew wrote:
> 
> I am implementing power management in my ALSA sound drivers. ALSA
> drivers are not working properly after resume. All registers values
> are proper and I am able to read back the codec register contents.
> 
> If I do a playback after resume then I am getting lots of "underrun".

As Liam already pointed, the underrun is usually irrelevant from the
codec registers, as codec chips don't control the DMA transfer.
So, it's likely a controller side problem.

> After a reboot playback is working fine.
> 
> Is there any known issues with ALSA power  management?

No.  Some drivers may have, but no problem in general.

> Why Ubuntu and Redhat does ALSA modules removal before suspend and
> insertion after resume?

They are either too lazy or too conservative :)


Takashi