1 files changed, 49 insertions, 0 deletions
diff --git a/0002-Bluetooth-btusb-check-conditions-before-enabling-USB-ALT-3-for-WBS.patch b/0002-Bluetooth-btusb-check-conditions-before-enabling-USB-ALT-3-for-WBS.patch
new file mode 100644
index 0000000..7aa972f
--- /dev/null
+++ b/0002-Bluetooth-btusb-check-conditions-before-enabling-USB-ALT-3-for-WBS.patch
@@ -0,0 +1,49 @@
+diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
+index 6d23308119d1..5cec719f6cba 100644
+--- a/drivers/bluetooth/btusb.c
++++ b/drivers/bluetooth/btusb.c
+@@ -516,6 +516,7 @@  static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
+ #define BTUSB_HW_RESET_ACTIVE	12
+ #define BTUSB_TX_WAIT_VND_EVT	13
+ #define BTUSB_WAKEUP_DISABLE	14
++#define BTUSB_ALT3_OK_FOR_WBS	15
+ 
+ struct btusb_data {
+ 	struct hci_dev       *hdev;
+@@ -1748,16 +1749,20 @@  static void btusb_work(struct work_struct *work)
+ 			/* Bluetooth USB spec recommends alt 6 (63 bytes), but
+ 			 * many adapters do not support it.  Alt 1 appears to
+ 			 * work for all adapters that do not have alt 6, and
+-			 * which work with WBS at all.
++			 * which work with WBS at all.  Some devices prefer
++			 * alt 3 (HCI payload >= 60 Bytes let air packet
++			 * data satisfy 60 bytes), requiring
++			 * MTU >= 3 (packets) * 25 (size) - 3 (headers) = 72
++			 * see also Core spec 5, vol 4, B 2.1.1 & Table 2.1.
+ 			 */
+-			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))
++			if (btusb_find_altsetting(data, 6))
++				new_alts = 6;
++			else if (test_bit(BTUSB_ALT3_OK_FOR_WBS, &data->flags) &&
++				 hdev->sco_mtu >= 72 &&
++				 btusb_find_altsetting(data, 3))
+ 				new_alts = 3;
++			else
++				new_alts = 1;
+ 		}
+ 
+ 		if (btusb_switch_alt_setting(hdev, new_alts) < 0)
+@@ -4733,6 +4738,7 @@  static int btusb_probe(struct usb_interface *intf,
+ 		 * (DEVICE_REMOTE_WAKEUP)
+ 		 */
+ 		set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
++		set_bit(BTUSB_ALT3_OK_FOR_WBS, &data->flags);
+ 	}
+ 
+ 	if (!reset)