Re: [PATCH v1 1/3] sound: usb: Add vendor's hooking interface

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Mar 24, 2022 at 05:10:42PM +0900, Oh Eomji wrote:
> In mobile, a co-processor can be used with USB audio to improve power
> consumption.  To support this type of hardware, hooks need to be added
> to the USB audio subsystem to be able to call into the hardware when
> needed.
> 
> The main operation of the call-backs are:
>   - 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
>   - other housekeeping
> 
> Known issues:
>   - This only supports one set of callback hooks, meaning that this only
>     works if there is one type of USB controller in the system.  This
>     should be changed to be a per-host-controller interface instead of
>     one global set of callbacks.

Sorry, but this limitation alone means that this is not going to be able
to be accepted.  Almost all real systems have multiple USB controllers
in the system and so, this will break in very bad ways on the majority
of devices in the world.

Please fix this up and make this per-USB-controller, as was requested
the last time this series was published.

thanks,

greg k-h