Re: [PATCH] Bluetooth: btusb: check SCO MTU before enabling USB ALT 3 for WBS
From: Pasi Kärkkäinen <hidden>
Date: 2021-07-20 09:32:21
Hi Pauli, On Fri, Jul 16, 2021 at 08:58:17PM +0300, Pauli Virtanen wrote:
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. Check that the MTU
condition is satisfied, and fall back to ALT 1 if not.
Tested with USB adapters (mtu<72, produce sound only with ALT1)
BCM20702A1 0b05:17cb, CSR8510A10 0a12:0001, and (mtu>=72, ALT3)
RTL8761BU 0bda:8771, Intel AX200 8087:0029 (after disabling ALT6).
Signed-off-by: Pauli Virtanen <redacted>
---Maybe add a Fixes: tag ? Thanks, -- Pasi
quoted hunk ↗ jump to hunk
drivers/bluetooth/btusb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c index a9855a2dd561..3ee66e415c4d 100644 --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c@@ -1763,9 +1763,11 @@ static void btusb_work(struct work_struct *work) /* Because mSBC frames do not need to be aligned to the * SCO packet boundary. If support the Alt 3, use the * Alt 3 for HCI payload >= 60 Bytes let air packet - * data satisfy 60 bytes. + * data satisfy 60 bytes. USB Alt 3 support also needs + * HFP transparent MTU >= 72 Bytes. */ - if (new_alts == 1 && btusb_find_altsetting(data, 3)) + if (new_alts == 1 && hdev->sco_mtu >= 72 && + btusb_find_altsetting(data, 3)) new_alts = 3; }-- 2.31.1