Re: [PATCH v2] Bluetooth: btusb: check conditions before enabling USB ALT 3 for WBS

quoted

Some USB BT adapters don't satisfy the MTU requirement mentioned in
commit e848dbd364ac ("Bluetooth: btusb: Add support USB ALT 3 for WBS")
and have ALT 3 setting that produces no/garbled audio. Some adapters
with larger MTU were also reported to have problems with ALT 3.

Add a flag and check it and MTU before selecting ALT 3, falling back to
ALT 1. Enable the flag for Realtek, restoring the previous behavior for
non-Realtek devices.

Tested with USB adapters (mtu<72, no/garbled sound with ALT3, ALT1
works) BCM20702A1 0b05:17cb, CSR8510A10 0a12:0001, and (mtu>=72, ALT3
works) RTL8761BU 0bda:8771, Intel AX200 8087:0029 (after disabling
ALT6). Also got reports for (mtu>=72, ALT 3 reported to produce bad
audio) Intel 8087:0a2b.

Signed-off-by: Pauli Virtanen <redacted>
Fixes: e848dbd364ac ("Bluetooth: btusb: Add support USB ALT 3 for WBS")

before I will apply this, I need Tested-by or Ack-by people that confirm that this fixes their issues now.

For 8087:0a2b (with broken mSBC audio since e848dbd364ac):

Tested-by: Michał Kępień <redacted>

It would be nice to get this into the stable tree as e848dbd364ac got
there in v5.13.3 (as 15407b14e27b) and v5.10.51 (as 05298f1733c6).

Thanks!

-- 
Best regards,
Michał Kępień