[alsa-devel] CS8409 Macbook Pro 2016 2017

[David Ulricht]

> The stuff in sound/i2c/* are mostly for the i2c bus on a PCI sound
> cards, an implementation independent from the standard i2c stuff.
>
> And, in your case, it's hard to know how the i2c bus is connected.
> If it's controlled over HD-audio GPIO pin (one for clk and one for
> data), then some stuff in sound/i2c can be re-used.  Or, if it's on
> another i2c bus, the story will be completely different...
>
I have the schematics of the CS8409. the i2c is connected to the GPIO of
the HDA.

MAX98374 has a Reset Low pin which is connected to GPIO 5 on the HDA
controller CS8409.  This must
be driven high, then wait for 1.5 ms.  Only then will the amps be out of
device shutdown.
GPIO6 is  8409_I2C_SCL
GPIO7 is  8409_I2C_SDA

GPIO5 is AUD_SPKRAMP_RESET_L

Knowing GPIO6 is the clock and GPIO7 is the data, how can I use them?
Can I use hda-verb /dev/snd/hwC0D0 0x01 XXX YYY ? what XXX YYY would be ?