Bug#1085850: regression: bluetooth game controller no longer connects

[Forest <forestix@nom.one>]

Package: src:linux
Version: 6.11.4-1
Severity: normal
X-Debbugs-Cc: forestix@nom.one

Dear Maintainer,

After upgrading from linux-image-6.11.2-amd64 to
linux-image-6.11.4-amd64, my Sony DualShock 4 v2 game controller no
longer connects over bluetooth.

I don't see any messages in dmesg or syslog when trying to
connect, nor any obviously relevant messages when I grep dmesg for
"bluetooth" or the driver names that I think are used on my system.
The device just seems to be ignored, and eventually gives up trying to
connect.

I haven't bisected this, but a local build of upstream kernel 6.11.5
(with Debian's config-6.11.4-amd64 as the .config file) restores
functionality. Also, I see several bluetooth fixes in the 6.11.5
changelog. I therefore suspect this regression originated upstream and
is fixed upstream.

-- Package-specific info:
** Kernel log: boot messages should be attached


-- System Information:
Debian Release: 12.7
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable'), (1, 'unstable')
Architecture: amd64 (x86_64)

Versions of packages linux-image-6.11.4-amd64 depends on:
ii  initramfs-tools [linux-initramfs-tool]  0.142+deb12u1
ii  kmod                                    30+20221128-1
ii  linux-base                              4.9

Versions of packages linux-image-6.11.4-amd64 recommends:
ii  apparmor  3.0.8-3

Versions of packages linux-image-6.11.4-amd64 suggests:
pn  debian-kernel-handbook  <none>
ii  firmware-linux-free     20200122-1
ii  grub-efi-amd64          2.06-13+deb12u1
pn  linux-doc-6.11          <none>

Versions of packages linux-image-6.11.4-amd64 is related to:
ii  firmware-amd-graphics     20240709-2~bpo12+1
ii  firmware-atheros          20230210-5
ii  firmware-bnx2             20230210-5
ii  firmware-bnx2x            20230210-5
ii  firmware-brcm80211        20230210-5
ii  firmware-cavium           20230210-5
ii  firmware-intel-sound      20230210-5
pn  firmware-intelwimax       <none>
ii  firmware-ipw2x00          20230210-5
ii  firmware-ivtv             20230210-5
ii  firmware-iwlwifi          20230210-5
ii  firmware-libertas         20230210-5
ii  firmware-linux-nonfree    20240709-2~bpo12+1
ii  firmware-misc-nonfree     20240709-2~bpo12+1
ii  firmware-myricom          20230210-5
ii  firmware-netxen           20230210-5
ii  firmware-qlogic           20230210-5
ii  firmware-realtek          20230210-5
ii  firmware-samsung          20230210-5
ii  firmware-siano            20230210-5
pn  firmware-ti-connectivity  <none>
pn  xen-hypervisor            <none>

-- no debconf information