Re: [PATCH] Bluetooth: btusb: treat 0bda:0002 as a generic HCI device

[Luiz Augusto von Dentz]

Hi Andrew,

On Fri, Aug 14, 2026 at 11:34 PM Andrew Bille <andrewbille@xxxxxxxxx> wrote:
>
> The 0bda:0002 Bluetooth controller reports itself as "CSR BS8510"
> and exposes a standard Bluetooth USB interface.
>
> It currently matches the vendor-wide Realtek quirk and is therefore
> initialized through btrtl. The controller does not respond to the
> Realtek-specific register access and initialization fails with:
>
>     Bluetooth: hci0: RTL: RTL: Read reg16 failed (-110)
>
> No Bluetooth controller is then available to userspace.
>
> Add an exact match for 0bda:0002 before the generic Realtek entry so
> that the device is handled as a generic USB HCI controller.

Okay, but what happens to the actual device with id 0x0002? Have you
confirmed with Realtek that no other device uses this ID? If another
device uses it, this change will break support for that device.

> With this change the controller registers successfully. Scanning,
> pairing and A2DP audio have been tested successfully.

I may fix your controller but if breaks others, it is not a long term
solution. To be clear, 0x0bda is controlled by Realtek; putting a CSR
device under it invades another vendor's domain.

> Fixes: a2698a9bf9b0 ("Bluetooth: btusb: Add Realtek 8723A/8723B/8761A/8821A support")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: ChatGPT:GPT-5.6-Sol
> Signed-off-by: Andrew Bille <andrewbille@xxxxxxxxx>
> ---
>  drivers/bluetooth/btusb.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 184e95c1625e..fb9fdf90a3b9 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -615,6 +615,9 @@ static const struct usb_device_id quirks_table[] = {
>         { USB_DEVICE(0x0489, 0xe130), .driver_info = BTUSB_REALTEK |
>                                                      BTUSB_WIDEBAND_SPEECH },
>
> +       /* CSR BS8510 device using a Realtek USB vendor ID */
> +       { USB_DEVICE(0x0bda, 0x0002) },
> +
>         /* Realtek Bluetooth devices */
>         { USB_VENDOR_AND_INTERFACE_INFO(0x0bda, 0xe0, 0x01, 0x01),
>           .driver_info = BTUSB_REALTEK },
> --
> 2.47.3
>


-- 
Luiz Augusto von Dentz