[alsa-devel] ALSA:usb audio Higher sample rates on usb audio no longer working.

[Pierre-Louis Bossart]

> [ Adding linux-usb ML to Cc, as it's a core USB issue ]
>
> So the device seems incorrectly advertising as if it were supporting
> UAC3 -- assuming the device is still not UAC3-capable.
>
> IOW, it's a buggy firmware.  We need some blacklisting, or revert the
> commit for now, unless any real UAC3 device comes up to the market.

IIRC an UAC3-capable device is required to expose a backwards-compatible 
configuration (either UAC1 or UAC2). Maybe an additional test can be 
done to harden the detection so that UAC3 is only chosen if indeed a 
second audio configuration is present as well.

I also vaguely recall there was talk about adding information in the BOS 
descriptor, but I don't know if this was ever published.

-Pierre