Re: [PATCH] Bluetooth: btusb: Always fallback to alt 1 for WBS

[Sjoerd Simons]

On Fri, Dec 18, 2020 at 10:23:08PM +0100, Marcel Holtmann wrote:
> Hi Trent,
> 
> > When alt mode 6 is not available, fallback to the kernel <= 5.7 behavior
> > of always using alt mode 1.
> > 
> > Prior to kernel 5.8, btusb would always use alt mode 1 for WBS (Wide
> > Band Speech aka mSBC aka transparent SCO).  In commit baac6276c0a9
> > ("Bluetooth: btusb: handle mSBC audio over USB Endpoints") this
> > was changed to use alt mode 6, which is the recommended mode in the
> > Bluetooth spec (Specifications of the Bluetooth System, v5.0, Vol 4.B
> > §2.2.1).  However, many if not most BT USB adapters do not support alt
> > mode 6.  In fact, I have been unable to find any which do.

> patch has been applied to bluetooth-next tree.

For easier application to the stable tree(s) this should probably get:
  Fixes: baac6276c0a9 ("Bluetooth: btusb: handle mSBC audio over USB Endpoints")

In my testing this indeed fixes mSBC audio with both a Belkin (Broadcom
BCM20702A, 050d:065a) and an Intel Bluetooth (8087:0a2b) adapters.

  Tested-By: Sjoerd Simons <sjoerd@xxxxxxxxxxxxx>

Regards,
  Sjoerd