[alsa-devel] [PATCH] ASoC: twl6040: Workaround for headset DC offset caused pop noise

Péter Ujfalusi peter.ujfalusi at ti.com
Wed Oct 12 12:45:33 CEST 2011

On Wednesday 12 October 2011 10:46:25 Mark Brown wrote:
> On Wed, Oct 12, 2011 at 11:55:15AM +0300, Péter Ujfalusi wrote:
> > I can not move the HS DAC power on/off to be handled by a supply
> > widget... Refcounting in a supply widget will not work for the power
> > down, since the supply widget will be turned off after the DAC widget.
> > At time when the DAC receives the PMD event the attached supply is
> > still on.
> > I can update the commit message to explicitly say that we need to turn
> > on both HS DAC at the same time, and we need to turn tem off at the
> > same time.
> I still don't understand what the problem is.  If nothing else you can
> do random register writes from an event on a supply widget...

I still have the code for the out of order McPDM shutdown which is using a 
supply widget attached to the codec's DAC/ADC.
The ordering of the two supply is not written in stone when both are attached 
to the same DAC.
Yes, I'm evaluating the possibility of the reordering the shutdown sequence in 
the core as you have suggested a while back. 

For this patch: I will merge the two DAC to one, and handle both of them in a 
single DAC widget. I have tested this and works fine.


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