[alsa-devel] [RFC] SoC WM8940 Driver

Jonathan Cameron jic23 at cam.ac.uk
Mon Apr 27 13:40:43 CEST 2009

>>>> +	SOC_SINGLE("Digital Loopback Switch adc to dac", WM8940_COMPANDINGCTL,
>>>> +		   0, 1, 0),
>>> This should be called Digital Sidetone Switch and probably ought to be a
>>> DAPM control - there's an ADC to DAC route.
>> I'll take your word for it!
> If you switch the ADC to the DAC then you've got an audio path between
> them.
Hi Mark,

I'm having some trouble getting my head around how to actually specify the audio
route for this Sidetone route.

As far as I can tell you can't specify the following,

{"DAC", "Digtal Sidetone Switch", "ADC"}
As in snd_soc_dapm_add_route only mux, switch and mixer controls can take
a control element.

I can find plenty of examples for cases where this path routes through a mixer
or mux, but in this simple case (it's either connected or not and no
volume controls are on that path) what do I do?

Nearest I can currently come up with is to insert a mux with only one option...



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