Re: [REGRESSION] RTL8761BU 0bda:a728: removing BROKEN_EXT_SCAN fixes 0x200c timeout

[Thorsten Leemhuis]

On 9/26/26 13:37, Andy Tsvetinskiy wrote:
> 7.3-rc4 checked, issue still exists

Thx for checking, and sorry, I had missed that Junjie send a patch to
fix this:

Bluetooth: btusb: drop BROKEN_EXT_SCAN quirk for 0bda:a728
https://lore.kernel.org/all/20260920020227.709800-1-junjie.cao@xxxxxxxxx/

You were copied. Please try that with 7.3-rc and reply with a
"Tested-by: " followed by your name and email, that would help a great deal.

Ciao, Thorsten

> пт, 25 сент. 2026 г. в 12:05, Thorsten Leemhuis <regressions@xxxxxxxxxxxxx>:
>>
>> On 9/18/26 15:37, Thorsten Leemhuis wrote:
>>> Lo!
>>> On 9/18/26 11:21, Andy Tsvetinskiy wrote:
>>>>
>>>>    This report concerns USB ID 0bda:a728, not 0bda:8771.
>>>>
>>>>    I have a Realtek RTL8761BUV USB Bluetooth adapter:
>>>>
>>>>    - USB ID: 0bda:a728
>>>>    - Product: Bluetooth 5.4 Radio
>>>>    - Firmware: rtl_bt/rtl8761bu_fw.bin
>>>>    - Firmware version: 0xdfc6d922
>>>>    - Running kernel: 6.18.51-1-lts
>>>>    - Distribution: Arch Linux
>>>>
>>>>    With the stock btusb driver, Bluetooth repeatedly failed with:
>>>>
>>>>        Bluetooth: hci0: command 0x200c tx timeout
>>>>        Bluetooth: hci0: Opcode 0x200c failed: -110
>>>>        Bluetooth: hci0: Unable to disable scanning: -110
>>>>        Bluetooth: hci0: Resetting usb device.
>>>>        usb 1-2.2: reset full-speed USB device
>>>>        Bluetooth: hci0: unexpected event for opcode 0x200c
>>>
>>> Thx for the report. Just replying to bring a few people into the loop
>>> that can help handling this: the Blutooth maintainers and developers
>>> which were involved in ca0583c2466174 ("Bluetooth: btusb: limit RTL8761B
>>> BROKEN_EXT_SCAN quirk to 0bda:a728") [v7.3-rc1] and 5ead2063611ae5
>>> ("Bluetooth: btrtl: fix RTL8761B/BU broken LE extended scan")
>>> [v7.2-rc1]. Ciao, Thorsten
>>
>> Hmm, seems nobody cares, so we need to go the next step: can you please
>> test if latest mainline (7.3-rc4 or later) is affected to rule out that
>> it's something specific to the stable series in question?
>>
>> Ciao, Thorsten
>>>>    The firmware was loaded successfully:
>>>>
>>>>        Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_fw.bin
>>>>        Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_config.bin
>>>>        Bluetooth: hci0: RTL: fw version 0xdfc6d922
>>>>
>>>>    The USB autosuspend setting was not the cause:
>>>>
>>>>        /sys/bus/usb/devices/1-2.2/power/autosuspend: -1
>>>>
>>>>    The current upstream fix ca0583c24661
>>>>    ("Bluetooth: btusb: limit RTL8761B BROKEN_EXT_SCAN quirk to 0bda:a728")
>>>>    is already present in my kernel. It sets BTUSB_BROKEN_EXT_SCAN for 0bda:a728.
>>>>
>>>>    I tested the opposite change locally in drivers/bluetooth/btusb.c:
>>>>
>>>>        - { USB_DEVICE(0x0bda, 0xa728), .driver_info = BTUSB_REALTEK |
>>>>        -                    BTUSB_BROKEN_EXT_SCAN },
>>>>        + { USB_DEVICE(0x0bda, 0xa728), .driver_info = BTUSB_REALTEK },
>>>>
>>>>    After rebuilding and reloading the btusb module:
>>>>
>>>>        systemctl stop bluetooth
>>>>        modprobe -r btusb
>>>>        modprobe btusb
>>>>        systemctl start bluetooth
>>>>
>>>>    Bluetooth scanning worked normally. A 20-second scan completed with:
>>>>
>>>>        Discovery started
>>>>        Discovering: yes
>>>>
>>>>    After loading the patched module, no new occurrences of the
>>>> following messages appeared:
>>>>
>>>>        Opcode 0x200c failed: -110
>>>>        Opcode 0x2042 failed
>>>>        command tx timeout
>>>>        Unable to disable scanning
>>>>        Resetting usb device
>>>>
>>>>    The patched driver is currently loaded and Bluetooth remains operational.
>>>>
>>>>    This suggests that different RTL8761BUV devices or firmware
>>>> revisions using USB ID 0bda:a728 may require different scan quirks. On
>>>> my device, keeping BTUSB_BROKEN_EXT_SCAN causes the legacy 0x200c
>>>> command to
>>>>  time out, while removing the quirk fixes the issue.
>>>>
>>>>    Relevant upstream reports:
>>>>
>>>>    https://linux-regtracking.leemhuis.info/regzbot/regression/lore/20260822141115.58815-1-kserwus@xxxxxxxxx/
>>>>
>>>>    https://bugzilla.redhat.com/show_bug.cgi?id=2521504
>>>>
>>>>    https://lkml.iu.edu/2608.2/12212.html
>>>>
>>>>    Please let me know if more logs, a full patch, or additional
>>>> testing is needed.
>>>>
>>>
>>
> 
>