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path: root/drivers/bluetooth/btusb.c
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Diffstat (limited to 'drivers/bluetooth/btusb.c')
-rw-r--r--drivers/bluetooth/btusb.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 488f110e17e2..2336f731dbc7 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -528,6 +528,7 @@ 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_USE_ALT3_FOR_WBS 15
struct btusb_data {
struct hci_dev *hdev;
@@ -1761,16 +1762,20 @@ 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 (btusb_find_altsetting(data, 3) &&
+ hdev->sco_mtu >= 72 &&
+ test_bit(BTUSB_USE_ALT3_FOR_WBS, &data->flags))
new_alts = 3;
+ else
+ new_alts = 1;
}
if (btusb_switch_alt_setting(hdev, new_alts) < 0)
@@ -3882,6 +3887,7 @@ static int btusb_probe(struct usb_interface *intf,
* (DEVICE_REMOTE_WAKEUP)
*/
set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
+ set_bit(BTUSB_USE_ALT3_FOR_WBS, &data->flags);
}
if (!reset)