[alsa-devel] [PATCH 3/3] ASoC: core: Change power state before rechecking endpoint

[Vinod Koul]

On Mon, Nov 23, 2015 at 05:06:41PM +0100, Lars-Peter Clausen wrote:
> On 11/23/2015 04:52 PM, Vinod Koul wrote:
> > From: Jeeja KP <jeeja.kp at intel.com>
> > 
> > For DAPM resume, we should first change the power state of the
> > card and then recheck the endpoints. This ensures the dapm is
> > resumed first and then userspace can resume the streams.
> 
> The problem is that DAPM uses the userspace state to decide whether to power
> up or not. So this change won't work, it will keep the endpoints suspended.

Well our observation are bit different...

When testing with aplay and suspending the system the DAPM was suspending
fine and then alsa suspends PCMs, but on resume the DAPM is resumed last and
the PCMs first, due to which the devices start underun!
The DAPM should be resumed first and then we should allow userspace access
(PCM resume from aplay)

The change of order here helps in that

-- 
~Vinod