I'm troubleshooting an issue with an ALSA driver I wrote for a very unique hardware platform. In this case I have an audio codec which only has a usable 'line-in' capture source. Currently the only mixer control I've created is a 'Master Playback Volume'. Do I need to create some kind of control for 'line-in'?

I'm unclear how to 'register' capture inputs so that they will be returned by the OSS mixer emulation's ioctl SOUND_MIXER_READ_RECMASK. Currently that ioctl returns 0 for my mixer device.

Also, is a control 'switch' such as 'Master Playback Switch' simply a mute control or is it intended to be any type of control which could have enumerated values?

Thanks,

Tim