I have a requirement to concurrently read both analog stereo inputs from a Cirrus CS4207 codec on a custom board. I had hoped to find a way to do this in userspace with a configuration of plugins. But like most ALSA drivers, pci/hda/patch_cirrus.c exposes just one analog stereo input, and relies on the mixer and/or mic detect to choose which hardware pin and which of the two hardware ADC channels to connect to the single capture input.

One possible solution would be to add an alternate capture device to the driver, and there seems to be an example of this approach in the patch_realtek driver.

My questions are what approach should be used to solve this kind of problem, and is there a better example source to look at instead of or in addition to patch_realtek.c?

Thanks, Bryan

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