Re: [PATCH] ALSA: hda/conexant: Set mic pin VREF to 0x24 on headset mic plug

[songxiebing]

Hi Takashi,

0x19 is configured as a mic pin, in cx_update_headset_mic_vref, it
executes cx_process_headset_plugin only after confirming that a mic
present is detected. A 4-pole headset is detected as either CTIA or
OMTP and sets 0x24, but the 3-pole mic case is not handled, so a
setting of 0x24 is added here.

>Hmm, it's a headset plug check code, and the fallback case you
>modified was supposed to be a headphone jack, no microphone.  That is,
>the state where a headphone is plugged without microphone into the
>headset jack, and in this case, it's wrong to enable the mic pin --
>you shouldn't be able to record from the mic at all in this particular
>case.
>
>So, there must be other case -- mic-only plug -- and that is where the
>mic pin is set up, too.
>
>
>Takashi