[alsa-devel] [PATCH v3 2/3] ASoC: soc-dapm: API to attach DAPM_SUPPLY to be used for dai

Péter Ujfalusi peter.ujfalusi at ti.com
Tue Sep 6 12:21:56 CEST 2011

On Saturday 03 September 2011 07:31:19 Mark Brown wrote:
> > The sequence I'm looking for is:
> > 1. pcm_trigger: stop DMA
> > 2. DAPM sequence starts
> > 3. DAC is turned off on the codec side
> > 4. OMAP4 McPDM can be stopped - stop it
> > 5. DAPM finishes up
> > 6. codec can be turned off
> Actually I think this is fine with my suggestion so long as you make the
> CODEC SYSCLK visible to DAPM and have the machine driver turn it off at
> some later point in the shutdown process (eg, in shutdown()).  That way
> the data paths will still be torn down by DAPM immediately but SYSCLK
> will still be generated.

I need to think about this.
Not sure how it will affect our system, if we do not have pmdown_time in the 
future, when we add full ABE support.
As a side note: I have found an issue with my earlier proposal (DAPM_SUPPLY 
attached to the codec's DAC/ADC): I can end up turning off the host side McPDM 
during audio activity (by muting the outputs/inputs runtime). It has the side 
effect of not recovering :o (also DMA stops, since the dai is stopped)

I'll get back to you on this soon (probably with a patch).


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