[PATCH] Bluetooth: btrtl: fix RTL8761B/BU broken LE extended scan

[Alexej Sidorenko <alexej@sidorenko.cz>]

RTL8761B and RTL8761BU devices report HCI version 5.1 but do not
support the LE Extended Scan commands. This causes repeated failures
with Opcode 0x2042 (LE Set Extended Scan Parameters) returning -EBUSY
when BlueZ attempts extended scanning while a connection is active.

Set HCI_QUIRK_BROKEN_EXT_SCAN for CHIP_ID_8761B to make BlueZ fall
back to legacy LE scan commands which the firmware supports correctly.

Tested with RTL8761BU (USB ID 0bda:a728) where the issue manifested
as continuous 'Opcode 0x2042 failed: -16' errors in dmesg whenever
a BLE connection was active.

Signed-off-by: Alexej Sidorenko <alexej@sidorenko.cz>
---
 drivers/bluetooth/btrtl.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c
index 62f9d4df3..49ecb18fe 100644
--- a/drivers/bluetooth/btrtl.c
+++ b/drivers/bluetooth/btrtl.c
@@ -1342,6 +1342,19 @@ void btrtl_set_quirks(struct hci_dev *hdev, struct btrtl_device_info *btrtl_dev)
 	if (!btrtl_dev->ic_info)
 		return;
 
+	switch (btrtl_dev->project_id) {
+	case CHIP_ID_8761B:
+		/* RTL8761B/BU reports HCI version 5.1 but does not support
+		 * the LE Extended Scan commands (Opcode 0x2042), causing
+		 * repeated -EBUSY failures when BlueZ attempts extended
+		 * scanning while a connection is active.
+		 */
+		hci_set_quirk(hdev, HCI_QUIRK_BROKEN_EXT_SCAN);
+		break;
+	default:
+		break;
+	}
+
 	switch (btrtl_dev->ic_info->lmp_subver) {
 	case RTL_ROM_LMP_8703B:
 		/* 8723CS reports two pages for local ext features,
-- 
2.45.2