Actually, I'm not so good at linux' internals to write drivers

I have investigated audio inputs/outpus with alsamixer before creating my fix. When device does not recognize headset, nothing happens in alsamixer, you're right. If it does recognize, a couple of outputs gets muted, a couple another gets unmuted. But muting/unmuting these outputs gives nothing.

As far as I understood, there are two distinct audio devices in the phone — "twl4030" for speaker and external mics and "dac32" for headset. And when device correctly recognizes headset insertion and ejection, it powers down one audio device and powers up another.

Anyway, after investigating all this for a couple of evenings, it seems to me that this is more hardware than software issue... I don't think audio device driver or something might be broken. But I can imagine easily that some electric contact in connector was failed...