[alsa-devel] [PATCH 044/112] ALSA: hda - More generic auto-mic switching for Realtek codecs

Raymond Yau superquad.vortex2 at gmail.com
Thu Jan 10 01:41:13 CET 2013

> This patch extends the capability of the auto-mic feature.
> Instead of limiting the automatic input-source selection only to the
> mics (internal, external and dock mics), allow it for generic inputs,
> e.g. switching between the rear line-in and the front mic.
> The logic is to check the attribute and location of input pins, and
> enable the automatic selection feature only if all such pins are in
> different locations (e.g. internal, front, rear, etc) and line-in or
> mic pins.  That is, if multiple input pins are assigned to a single
> location, the feature isn't enabled because we don't know the
> priority.
> (You may wonder why this restriction doesn't exist for the headphone
>  automute.  The reason is that the output case is different from the
>  input: the input source is an exclusive selection while the output
>  can be multiplexed.)
> Note that, for avoiding regressions, the line-in auto switching
> feature isn't activated as default.  It has to be set explicitly via
> spec->line_in_auto_switch flag in a fixup code.

Is this feature automatically disabled when rear Mic or line in Jack is
retasked as output ?

Does it mean that multi channel capture will not be implemented since it is
conflict with both dynamic adc  switching and auto Mic selection ?

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