[alsa-devel] ASoC: Multiplexing CODECs together

[Mike Looijmans]

I'm using multiple TI codecs and an OMAP-L138.

So far, I've been able to use a single codec. I've changed the davinci-mcasp.c code to respond to "set_tdm_slot", which I now use to tell it which serializers must be activated for capture and playback. This works fine now, any codec on any serializer port can be used independently now.

I want to take the next step and have two codecs "mixed" together, so that two codecs form a  4-channel ADC device. They are all running on the same clocks.

My idea so far is to create a "multiplex" codec driver, which exports mixer controls to tell it which real codecs to activate. No problem so far. Now when an application starts capture from the multiplex, it should call the "real" codecs (e.g. set_hw_params). This poses several problems, because the structs passed to the calls contain information that is irrelevant for the codec(s) that must actually do the work.
Creating a multiplex codec, as opposed to say a dai, made sense to me because an application can "select" it.

So my question is, Am I on the right track here? Or should I forget about the codec multiplex driver, because I have to write something completely?

Or is this not the correct list to ask this kind of questions? In which case I'd be happy to learn where I might get some tips?


Met vriendelijke groet / kind regards,

Mike Looijmans

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E-mail: mike.looijmans at topic.nl
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