[alsa-devel] [PATCH] ASoC: dapm: Fix locking during codec shutdown

[Liam Girdwood]

On Fri, 2012-07-06 at 17:02 +0100, Mark Brown wrote:
> On Fri, Jul 06, 2012 at 04:57:05PM +0100, Liam Girdwood wrote:
> > Codec shutdown performs a DAPM power sequence that might cause conflicts
> > and/or race conditions if another stream power event is running simultaneously.
> > Use card's dapm mutex to protect any potential race condition between them.
> 
> There's a bigger problem here if we're managing to run into this - the
> shutdown function is only supposed to be being called while the system
> is in the middle of shutting down so we've probably got a bunch of other
> races further up the stack to worry about too...

I don't think there is anything explicitly stopping a power off from
happening during a stream shutdown atm without this patch. It was
reported to me that this would fail 1 in 20 times on a certain device
and that the above patch fixed the issue (1200 tests completed OK after
the patch).

I do think we need this patch atm since we are accessing the same
resources as the stream event.

Liam