[alsa-devel] [PATCH] ASoC: max98357a: Fix speaker pop when starting playback

[Ezequiel Garcia]

On Tue, 2018-03-27 at 19:36 +0800, Mark Brown wrote:
> On Thu, Mar 22, 2018 at 10:01:32AM -0300, Ezequiel Garcia wrote:
> > On Thu, 2018-03-22 at 09:54 +0800, Mark Brown wrote:
> > > On Wed, Mar 21, 2018 at 07:30:15PM -0300, Ezequiel Garcia wrote:
> > > > +- sdmode-delay : specify a delay time for SD_MODE pin.
> > > > According
> > > > +        to the DAC datasheet, if LRCLK is removed while BCLK
> > > > is
> > > > present,
> > > > +        the DAC output can cause loud pop/crack noises. This
> > > > property
> > > > +        specifies a delay for the SD_MODE pin assert, required
> > > > to
> > > > +        eliminate the noise.
> > > Why is this configurable?  This sounds like something entirely
> > > within
> > > the digital domain of the device rather than something that
> > > depends
> > > on
> > > board configuration and it's hard to see how someone would
> > > configure
> > > this.
> > The amount of delay needed seems specific to the CPU DAI,
> > not specific to the DAC. The CPU DAIs or the machine 
> > could specify this as a parameter, but I can't don't see how.
> 
> This sounds like it's just trying to reimplement the digital mute
> feature we already have, it sounds more like what you're seeing is
> noise
> playing out of the SoC at the start of playback due to startup issues
> or non-flushed FIFOs.  Can you try implementing there please?
> 

OK, I'll see how it goes using digital mute.
Please discard v2 then.

Thanks,
Eze