[alsa-devel] [PATCH] ASoC: WM8903: Implement DMIC support

Julian Scheel julian at jusst.de
Fri Oct 14 12:34:21 CEST 2011

Am Montag, den 18.04.2011, 20:58 -0600 schrieb Stephen Warren:
> In addition to the currently supported analog capture path, the WM8903
> also supports digital mics.
> The analog and digital capture paths are exclusive; a mux is present to
> select the capture source.
> Logically, the mux exists to select the decimator's input, from either
> the ADC or DMIC block outputs. However, the ADC power domain also
> includes the DMIC interface. Consequently, this change represents the
> mux as existing immediately before the ADC, and selecting between the
> Input PGA and DMIC block outputs.
> An alternative might be to represent the mux in its correct location,
> and associate the ADC power enable controls with both the real ADC, and
> a fake ADC for the DMIC?


actually the wm8903 codec needs GPIO1 and GPIO2 to be configured
properly to be able to use DMIC actually. I would propose to
automatically configure these to DMIC-mode whenever ADCINPUT is set to
DMIC. Would you agree with this procedure?
I would prepare a patch which changes all relevant registers then.


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