[alsa-devel] ASoC: wm9712: Microphone doesn't work: Mux handling broken?

Mark Brown broonie at opensource.wolfsonmicro.com
Sat May 12 13:51:31 CEST 2012

On Sat, May 12, 2012 at 02:15:56AM +0200, Christoph Fritz wrote:

> They refuse to change their Item0 because they are defined as
> SND_SOC_DAPM_MUX without a correlating path->name so that
> snd_soc_dapm_mux_update_power() (in sound/soc/soc-dapmc) doesn't
> change anything.

A route into a mux without a path name (other than a supply) just isn't
meaningful and I'm surprised it ever worked.

> It works in 2.6.33, but current kernel has different mux handling and
> it seems that no one since cared that much about microphone support.

It's nothing to do with microphones really, it's more that AC'97 CODECs
are rarely used with modern kernels as the boards that use AC'97 are
mostly quite old and suffer performance issues with modern software
stacks so newer kernels haven't been getting much testing with them.

> Mark, can you confirm this, purpose a fix or even come up with
> a patch?

Just filling in the appropriate mux value in the relevant route should
do the trick.  Looking at the code it looks like the widget isn't hooked
into the audio routing map at all so I'm a little surprised.  I'm out of
the office at the minute and so can't readily set up a test system
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