Bluetooth: btusb: Add support USB ALT 3 for WBS

Because mSBC frames do not need to be aligned to the SCO packet
boundary. Using USB ALT 3 let HCI payload >= 60 bytes, let mSBC
data satisfy 60 Bytes avoid payload unaligned situation and fixed
some headset no voise issue.

USB Alt 3 supported also need HFP support transparent MTU in 72 Bytes.

Signed-off-by: Hilda Wu <hildawu@realtek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 626a140e0ddc60ec04b66511b1aaa3a82d797c12..b015dcecfb13521ea28faa46a4a1651d97629439 100644 (file)
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -1754,6 +1754,13 @@ static void btusb_work(struct work_struct *work)
                         * which work with WBS at all.
                         */
                        new_alts = btusb_find_altsetting(data, 6) ? 6 : 1;
+                       /* 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.
+                        */
+                       if (new_alts == 1 && btusb_find_altsetting(data, 3))
+                               new_alts = 3;
                }
 
                if (btusb_switch_alt_setting(hdev, new_alts) < 0)