Having the same problem with a 2017 12” Macbook (the Macbook10,2). The microphone shows up as “(unplugged)” in pavucontrol and pacmd regardless of if I have the headset plugged into the combo jack or not. Headphones are detected and work. The internal mic is still accessible and the Microphone input seems to be mirrorring it (could be to do with some chip-level switching that somehow doesn’t happen on Linux?). I’ve tried inputting all choices of model available in the CS4208 quirk list for PulseAudio (there isn’t one for my particular model) into alsa-base.conf and nothing has changed (having nothing in alsa-base.conf, which I did before attempting this fix, also makes no difference). I’m running Debian 10 with kernel 4.19.0-17-amd64.
Having the same problem with a 2017 12” Macbook (the Macbook10,2). The microphone shows up as “(unplugged)” in pavucontrol and pacmd regardless of if I have the headset plugged into the combo jack or not. Headphones are detected and work. The internal mic is still accessible and the Microphone input seems to be mirrorring it (could be to do with some chip-level switching that somehow doesn’t happen on Linux?). I’ve tried inputting all choices of model available in the CS4208 quirk list for PulseAudio (there isn’t one for my particular model) into alsa-base.conf and nothing has changed (having nothing in alsa-base.conf, which I did before attempting this fix, also makes no difference). I’m running Debian 10 with kernel 4.19.0-17-amd64.