[PATCH] ASoC: rt715: add main capture switch and main capture volume control

[Pierre-Louis Bossart]

> My suggestions are (pick one):
> 
> 1) create one multichannel control and remove the stereo controls when the
> hardware is detected (no functionality dup)

we can't remove controls that existed before, this might break userspace 
with older UCM files that touch those ADC07 and ADC27. That's why we 
added a new one, to be backwards compatible with a user updates their 
kernel.

> 2) create proper vmaster control like for HDA playback

That might be the better option. What was suggested in this patch is 
essentially to introduce a layer that drives the actual controls, but it 
was done 'manually' and may not follow the proper rules.

That said I know absolutely nothing about 'vmaster controls', pointers 
to a typical example would be greatly appreciated.

> 3) wait until UCM can describe this hardware and set the DAC values manually
> to a sensible value via sequences (the specific hardware levels can be set
> using the conditions in UCM)

Not an option, there are products that need to ship soon.

> BTW: I see lack of analog volume level controls also for other SDW hardware
> (with the RT1308 amplifier). It's a bit pitty that the audio basics are
> ignored here. Everyone wants to control the analog levels at first for audio
> I/O and then to modify the samples in the digital stream.

I agree, there was an oversight in initial UCM files where the SOF 
controls modifying the digital parts were used across the board. This 
was mandatory for DMICs controlled by SOF but all other streams should 
have been controlled by controls exposed by external devices.