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authorPauli Virtanen <pav@iki.fi>2021-07-26 21:02:06 +0300
committerLuiz Augusto von Dentz <luiz.von.dentz@intel.com>2021-08-10 21:28:49 +0300
commit55981d3541812234e687062926ff199c83f79a39 (patch)
treec50746b417defc1f48f2410bf082f8df2717ae98 /drivers/bluetooth
parente1dee2c1de2b4dd00eb44004a4bda6326ed07b59 (diff)
downloadlinux-55981d3541812234e687062926ff199c83f79a39.tar.xz
Bluetooth: btusb: check conditions before enabling USB ALT 3 for WBS
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 <pav@iki.fi> Fixes: e848dbd364ac ("Bluetooth: btusb: Add support USB ALT 3 for WBS") Tested-by: Michał Kępień <kernel@kempniu.pl> Tested-by: Jonathan Lampérth <jon@h4n.dev> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Diffstat (limited to 'drivers/bluetooth')
-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)