Re: [RFC PATCH] ASoC: wm_adsp: Change ADSPs to be mixer widgets rather the PGAs

[Charles Keepax <ckeepax@opensource.wolfsonmicro.com>]

On Wed, Dec 18, 2013 at 04:19:02PM +0000, Mark Brown wrote:
> On Wed, Dec 18, 2013 at 02:14:23PM +0000, Charles Keepax wrote:
> > On Wed, Dec 18, 2013 at 01:23:43PM +0000, Mark Brown wrote:
> 
> > > Not the physical output, the DSP output into the rest of the device.  It
> > > would be very surprising if it powered up making noise.
> 
> > Regrettably, I don't believe there is a way to mute the output of
> > the DSP. Muting the physical output does fix the issue.  I could
> 
> So the DSP powers up outputing stuff?  That seems like an interesting
> design decision (it might need something to reset the buffers on power
> down I guess).

It is not sure it is so much a design decision but there is an
audible pop when the DSP core enable bit is set if it is
connected to an unmuted output.

> 
> > look at seperating out the physical power up of the core and
> > starting the firmware to be seperate widgets, that might also
> > fix the issue and would mean the firmware wouldn't run until the
> > input signal was clean, but I am not sure if feels that neat a
> > solution.
> 
> That sort of split is something I'd considered doing in the past anyway
> - it would be beneficial to be able to overlap the DSP startup with
> other activities so the delays while bringing up the outputs could be
> happening while the DSPs are downloading firmware or the firmware is
> starting up for example.  You could also overlap stuff with the RAM
> startup if that's now taking longer.

Ok this looks like a potentially viable solution, and I hadn't
considered the potential benefits it could have to speed up the
audio path bring up time, I shall have a bash at implementing it
and see where I get to.

Thanks,
Charles