[Bug 2146761] Re: Bluetooth audio headset regression on 7.0.0-10-generic: Shokz OpenComm2 disconnects, works on 6.19.0-6-generic

Confirmed this fix on Ubuntu 26.04 (resolute), kernel 7.0.0-7-generic
(7.0.0-rc3).

Built bluetooth.ko from linux-source-7.0.0 with upstream commit
537b583e6af82ead3f7a1074d51d5765f647ff01 ("Bluetooth: L2CAP: Fix
regressions caused by reusing ident") applied to
net/bluetooth/l2cap_core.c and include/net/bluetooth/l2cap.h. Loaded the
patched module and the issue is resolved — A2DP transport channel
completes configuration, audio works, and HFP/HSP connects as well.

Without the fix, the L2CAP Configure Request for the AVDTP transport
channel reuses ident 1 (already used by the signaling channel), and the
headset drops it silently. This stalls A2DP for ~30 seconds until the
headset ABORTs.

Affected devices confirmed so far: Marshall Major IV, Bose QC35.

Detailed trace analysis and btmon captures in the upstream BlueZ issue:
https://github.com/bluez/bluez/issues/1992

** Bug watch added: github.com/bluez/bluez/issues #1992
https://github.com/bluez/bluez/issues/1992

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https://bugs.launchpad.net/bugs/2146761

Title:
Bluetooth audio headset regression on 7.0.0-10-generic: Shokz
OpenComm2 disconnects, works on 6.19.0-6-generic

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Resolute:
Confirmed

Bug description:
After the system update on March 29, 2026, my Bluetooth audio headset
(Shokz OpenComm2 / OpenComm2 by Shokz_II) stopped working on kernel
7.0.0-10-generic.

The headset either disconnects within about 10 seconds after
connect, or the connection is canceled and audio profiles fail to come
up.

If I reboot the same machine into the previous kernel
6.19.0-6-generic, the headset works again without changing userspace
packages or pairing state.

This looks like a kernel regression in 7.0.0-10-generic.

Working kernel:
6.19.0-6-generic
Linux book 6.19.0-6-generic #6-Ubuntu SMP PREEMPT_DYNAMIC Wed Feb 18 15:48:21 UTC 2026 x86_64 GNU/Linux

Broken kernel:
7.0.0-10-generic
From previous boot kernel log:
Linux version 7.0.0-10-generic (buildd@lcy02-amd64-051) (x86_64-linux-gnu-gcc (Ubuntu 15.2.0-15ubuntu2) 15.2.0, GNU ld (GNU Binutils for Ubuntu) 2.46) #10-Ubuntu SMP
PREEMPT_DYNAMIC Thu Mar 19 10:24:42 UTC 2026 (Ubuntu 7.0.0-10.10-generic 7.0.0-rc4)

Userspace versions at the time:
bluez 5.85-4
pipewire 1.6.2-1ubuntu1
wireplumber 0.5.13-1ubuntu1
gnome-shell 50.0-0ubuntu2
same userspace + new kernel fails.

Steps to reproduce:
1. Boot kernel 7.0.0-10-generic.
2. Power on the Shokz OpenComm2 headset.
3. Connect it from GNOME Settings or with bluetoothctl.
4. Wait a few seconds.

Expected result:
The headset should stay connected and its audio profile should become usable.

Actual result:
- Another Bluetooth device (Logitech Pebble mouse) still works, so this is not a total Bluetooth failure.
- I tested re-pairing the headset and rebooting the headset; that did not help on 7.0.0-10-generic.
- I tested disabling Bluetooth headset autoswitch behavior in WirePlumber; that did not fix it on 7.0.0-10-generic.
- There is no GNOME Shell crash here; this does not appear to be the old gnome-shell bug 2138654.

Relevant bluetoothd log lines from the broken boot:
- src/profile.c:ext_connect() Hands-Free Voice gateway failed connect to A0:0C:C3:E1:3F:7C: Connection reset by peer (104)
- src/service.c:btd_service_connect() a2dp-sink profile connect failed for A0:0C:C3:E1:3F:7C: Device or resource busy
- profiles/audio/avdtp.c:avdtp_connect_cb() connect to A0:0C:C3:E1:3F:7C: Connection refused (111)
- profiles/audio/avctp.c:avctp_connect_cb() HUP or ERR on socket: Connection refused (111)
- profiles/audio/avctp.c:avctp_connect_cb() HUP or ERR on socket: Connection timed out (110)

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