Re: [regression 6.12.y] After backport of 980084de4d9b ("Bluetooth: btusb: Add ASUS USB-BT540 for Realtek 8761CU") bluethooth not anymore working on 0b05:1bef ASUSTek Computer, Inc. Bluetooth Controller (requests firmware)

[Salvatore Bonaccorso <carnil@debian.org>]

Ciao Thorsten,

Thanks for looking into this regression as well.

On Mon, Oct 12, 2026 at 02:00:18PM +0200, Thorsten Leemhuis wrote:
> On 10/4/26 18:29, Sasha Levin wrote:
> >> In Debian Erik Brangs reported that after the update from 6.12.107 to
> >> 6.12.111, specifically with the backport of 980084de4d9b ("Bluetooth:
> >> btusb: Add ASUS USB-BT540 for Realtek 8761CU") Bluetooth is not
> >> anymore working, the full report is found at
> >> https://bugs.debian.org/1149377 .
> >>
> >> | [   38.138881] Bluetooth: hci0: RTL: firmware file rtl_bt/rtl8761cu_fw not found
> > 
> > The stable code matches mainline. The failure is a missing firmware file:
> > rtl_bt/rtl8761cu_fw.bin has been in linux-firmware only since 20251111,
> > and Debian trixie's firmware-realtek 20250410-2 does not have it.
> > 
> > Marcel, Luiz: could you, or Christoph Zwerschke as the author of the ID
> > commit, send an upstream revert, or a fallback to ROM firmware when
> > rtl8761cu_fw.bin is missing? Stable will take it for 7.2, 6.18 and 6.12
> > through the normal Cc: stable route once it is in mainline.
> 
> Hmmm, that was a week (granted: with the LPC) ago and nothing happened.
> Anyone working on this?
> 
> If not: Should we revert 980084de4d9b and its backports? Or only the
> backports to older stable series?
> 
> Strictly speaking it should be the former due to our policies wrt to
> firmware -- but I guess most users of a more recent kernels also have a
> newer firmware, so I wonder if reverting the change might do more harm
> then good now.

If my understanding is correct from a earlier fixed regression in the
ariea, aka
https://lore.kernel.org/regressions/0fd8c1c9-7f56-4bcb-a727-e4386d8ef094@online.de/
should then not only 980084de4d9b ("Bluetooth: btusb: Add ASUS
USB-BT540 for Realtek 8761CU") be reverted, but as well along
6f0624b4427e ("Bluetooth: btusb: Add ASUS USB-BT600 for Realtek
8761CU") and as well 4a23ce935f74 ("Bluetooth: btrtl: Add the support
for RTL8761CUV")?

Regards,
Salvatore