[PATCH] ANDROID: sound: usb: Add vendor's hooking interface

[Christoph Hellwig]

On Wed, Jun 17, 2020 at 11:18:24AM +0900, JaeHun Jung wrote:
> In mobile, a co-processor is used when using USB audio
> to improve power consumption.
> hooking is required for sync-up when operating
> the co-processor. So register call-back function.
> The main operation of the call-back function is as follows:
> - Initialize the co-processor by transmitting data
>   when initializing.
> - Change the co-processor setting value through
>   the interface function.
> - Configure sampling rate
> - pcm open/close
> 
> Bug: 156315379

None of that is acceptable without an in-tree user.  Never mind that
the interface just seems horrible.  I'm pretty sure we could do
somehting much better and more specific based on the actual needs of
the user, so please post it.