[PATCH v2 1/2] Bluetooth: btusb: mediatek: Fix leaked runtime PM reference in reset

MT7925 on HP Pro Mini 260 sometimes timed out during reloading driver
and reset usb device. btusb_suspend is not called again after closing
bluetooth interface.

 usbcore: registered new interface driver btusb
 Bluetooth: hci0: HW/SW Version: 0x00000000, Build Time: 20260605184935
 Bluetooth: hci0: Execution of wmt command timed out
 Bluetooth: hci0: Failed to send wmt patch dwnld (-110)
 Bluetooth: hci0: Failed to set up firmware (-110)
 usb 3-10: reset high-speed USB device number 4 using xhci_hcd
 Bluetooth: hci0: HW/SW Version: 0x00000000, Build Time: 20260605184935
 Bluetooth: hci0: Device setup in 1856545 usecs
 Bluetooth: hci0: AOSP extensions version v1.00
 Bluetooth: hci0: AOSP quality report is supported
 Bluetooth: MGMT ver 1.23

btusb_mtk_reset calls usb_autopm_get_interface to resume the device
before driving the hardware reset, but never calls the matching
usb_autopm_put_interface. Every hardware reset therefore leaks a PM
usage reference of the interface, preventing the device from being
runtime suspended again until it is unbound.

Add BTUSB_USB_RESET_ACTIVE flag and set it before usb_queue_reset_device.
Release the PM reference in btusb_disconnect if this flag is set.

Fixes: 25b6d7593a3a ("Bluetooth: btmtk: introduce btmtk reset work")
Assisted-by: Claude:qwen3.8-max
Signed-off-by: Jiajia Liu <[email protected]>
---

Changes in v2:
- Fix the race window (sashiko)
  Add and set BTUSB_USB_RESET_ACTIVE flag before usb_queue_reset_device.
  Release PM reference in btusb_disconnect if this flag is set.

Changes in v1:
- add usb_autopm_put_interface after usb_queue_reset_device

---
 drivers/bluetooth/btusb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 184e95c1625e..45a726bed0dd 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -957,6 +957,7 @@ struct qca_dump_info {
 #define BTUSB_USE_ALT3_FOR_WBS	15
 #define BTUSB_ALT6_CONTINUOUS_TX	16
 #define BTUSB_HW_SSR_ACTIVE	17
+#define BTUSB_USB_RESET_ACTIVE	18
 
 struct btusb_data {
 	struct hci_dev       *hdev;
@@ -2915,6 +2916,7 @@ static int btusb_mtk_reset(struct hci_dev *hdev, void *rst_data)
 
 	err = btmtk_usb_subsys_reset(hdev, btmtk_data->dev_id);
 
+	set_bit(BTUSB_USB_RESET_ACTIVE, &data->flags);
 	usb_queue_reset_device(data->intf);
 	clear_bit(BTMTK_HW_RESET_ACTIVE, &btmtk_data->flags);
 
@@ -4497,6 +4499,9 @@ static void btusb_disconnect(struct usb_interface *intf)
 	if (data->reset_gpio)
 		gpiod_put(data->reset_gpio);
 
+	if (test_bit(BTUSB_USB_RESET_ACTIVE, &data->flags))
+		usb_autopm_put_interface_no_suspend(data->intf);
+
 	if (intf == data->intf) {
 		if (data->isoc)
 			usb_driver_release_interface(&btusb_driver, data->isoc);
-- 
2.55.0