[PATCH 4/6] ASoC: Intel: bytcr_rt5640: Add support for a second headphones output

[Pierre-Louis Bossart]

> I've also figured out how jack-detect works, since the codec's GPIO1 is used for the external-hp-amp enable, the jack-detect signals are directly connected to the Bay Trail SoC's GPIOs:
> 
>   -gpioget 'INT33FC:02' 14 && gpioget 'INT33FC:00' 0 && gpioget 'INT33FC:00' 3
>    Nothing inserted: 1 1 0
>    Headset  in dock: 0 1 0
>    Headphon in dock: 0 1 1
>    Headset  in tabl: 1 0 0
>    Headphon in tabl: 1 0 0
>    Conclusion:
>    GPO2 pin 14: !jack in dock
>    GPO0 pin  0: !jack in tablet
>    GPO0 pin  3: 1 when jack in dock with no mic

I am a bit confused about the logic. Could you have a case with 1 1 1
(separate headphones in tablet and dock jacks)?

> 
> And I believe that the mic on the tablet jack can be detected using the normal micBIAS over current detection which is normally also used.
> 
> This will require some special jack-detect handling inside the machine driver for this model. I plan to also add support for this when I have some time to work on this.
> """
> 
> So ATM this requires an explicit user-choice, but I plan to add support for
> jack-detect on both jacks when I've some more time to work on this.

Thanks!