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

[Mark Brown]

On Wed, Dec 18, 2013 at 10:53:44AM +0000, Charles Keepax wrote:

> Was also considering if it would be worth adding an
> additional snd_soc_dapm_dsp id? That could sit between
> mixers and pgas, but I can't really see any obvious issue
> with treating the DSP as a mixer and it is a much simpler
> change. Although I am open to writing the other change if it
> is preferred?

One of the issues here was trying to ensure that the DSP started up with
its inputs stable so noise from them starting didn't propagage into the
algorithm and confuse it.  The expecation with putting it as a PGA was
that it would start with the outputs mute and do a digital unmute to
bring them up.  Since everything is digital this should all be more
robust than it would be for analogue.

If anything I'd have a specific DSP widget type which is one of the last
things to start.
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