[PATCH v2] ALSA: usb-audio: Filter out unsupported sample rates on Focusrite devices

[Takashi Iwai]

On Sat, 18 Apr 2020 19:58:15 +0200,
Alexander Tsoy wrote:
> 
> Many Focusrite devices supports a limited set of sample rates per
> altsetting. These includes audio interfaces with ADAT ports:
>  - Scarlett 18i6, 18i8 1st gen, 18i20 1st gen;
>  - Scarlett 18i8 2nd gen, 18i20 2nd gen;
>  - Scarlett 18i8 3rd gen, 18i20 3rd gen;
>  - Clarett 2Pre USB, 4Pre USB, 8Pre USB.
> 
> Maximum rate is exposed in the last 4 bytes of Format Type descriptor
> which has a non-standard bLength = 10.
> 
> Tested-by: Alexey Skobkin <skobkin-ru at ya.ru>
> Signed-off-by: Alexander Tsoy <alexander at tsoy.me>

Applied now.  It deserves for Cc to stable, so added the tag, too.


thanks,

Takashi