[Bug 220344] Intel AX211 bluetooth randomly disconnects and reconnects, started after kernel update

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220344

--- Comment #4 from Tal Licht (tal.lich@gmail.com) ---
I've tried going back to the bluetooth firmware that was current at the
date the computer was originally installed - 9/Sep/2023.

On this date, these firmware files were current:

ibt-0040-0041.sfi - commit 555452997994b250477de4a03b322dc53513d05a dated
2023-08-28
ibt-0040-0041.ddc - commit b7e0c80b00bb4e3d4c845f2270c5c0c8262154ca dated
2021-09-15
iwlwifi-so-a0-gf-a0-86.ucode -
commit f27dec616e29e44cd90645926c1459639d112c3d dated 2023-11-16 - *this is
still the current version today*

I switched the files in /lib/firmware to these versions and rebooted:

root@licht-t14s:~# dmesg | grep -E '(hci0|iwlwifi)'
[   30.809390] iwlwifi 0000:00:14.3: enabling device (0000 -> 0002)
[   30.830430] iwlwifi 0000:00:14.3: Detected crf-id 0x400410, cnv-id
0x80400 wfpm id 0x80000020
[   30.830491] iwlwifi 0000:00:14.3: PCI dev 51f1/0090, rev=0x370,
rfid=0x2010d000
[   30.835929] iwlwifi 0000:00:14.3: TLV_FW_FSEQ_VERSION: FSEQ Version:
0.0.2.41
*[   30.836818] iwlwifi 0000:00:14.3: loaded firmware version 86.fb5c9aeb.0
so-a0-gf-a0-86.ucode op_mode iwlmvm*
[   30.839236] Bluetooth: hci0: Device revision is 0
[   30.839241] Bluetooth: hci0: Secure boot is enabled
[   30.839242] Bluetooth: hci0: OTP lock is enabled
[   30.839243] Bluetooth: hci0: API lock is enabled
[   30.839244] Bluetooth: hci0: Debug lock is disabled
[   30.839245] Bluetooth: hci0: Minimum firmware build 1 week 10 2014
[   30.839246] Bluetooth: hci0: Bootloader timestamp 2019.40 buildtype 1
build 38
[   30.840962] Bluetooth: hci0: DSM reset method type: 0x00
*[   30.844291] Bluetooth: hci0: Found device firmware:
intel/ibt-0040-0041.sfi*
[   30.844304] Bluetooth: hci0: Boot Address: 0x100800
*[   30.844305] Bluetooth: hci0: Firmware Version: 254-28.23*
[   30.982422] iwlwifi 0000:00:14.3: Detected Intel(R) Wi-Fi 6E AX211
160MHz, REV=0x370
[   31.158040] iwlwifi 0000:00:14.3: WFPM_UMAC_PD_NOTIFICATION: 0x20
[   31.158093] iwlwifi 0000:00:14.3: WFPM_LMAC2_PD_NOTIFICATION: 0x1f
[   31.158101] iwlwifi 0000:00:14.3: WFPM_AUTH_KEY_0: 0x90
[   31.158109] iwlwifi 0000:00:14.3: CNVI_SCU_SEQ_DATA_DW9: 0x0
[   31.158396] iwlwifi 0000:00:14.3: loaded PNVM version e28bb9d7
[   31.159564] iwlwifi 0000:00:14.3: RFIm is deactivated, reason = 4
[   31.174653] iwlwifi 0000:00:14.3: Detected RF GF, rfid=0x2010d000
[   31.244329] iwlwifi 0000:00:14.3: base HW address: 10:f6:0a:05:ba:09
[   31.260051] iwlwifi 0000:00:14.3: iwlmvm doesn't allow to disable BT
Coex, check bt_coex_active module parameter
[   31.294784] iwlwifi 0000:00:14.3 wlp0s20f3: renamed from wlan0
[   31.793193] iwlwifi 0000:00:14.3: WFPM_UMAC_PD_NOTIFICATION: 0x20
[   31.793252] iwlwifi 0000:00:14.3: WFPM_LMAC2_PD_NOTIFICATION: 0x1f
[   31.793260] iwlwifi 0000:00:14.3: WFPM_AUTH_KEY_0: 0x90
[   31.793269] iwlwifi 0000:00:14.3: CNVI_SCU_SEQ_DATA_DW9: 0x0
[   31.794692] iwlwifi 0000:00:14.3: RFIm is deactivated, reason = 4
[   31.892352] iwlwifi 0000:00:14.3: Registered PHC clock: iwlwifi-PTP,
with index: 0
[   32.392539] Bluetooth: hci0: Waiting for firmware download to complete
[   32.393277] Bluetooth: hci0: Firmware loaded in 1512675 usecs
[   32.393369] Bluetooth: hci0: Waiting for device to boot
[   32.409352] Bluetooth: hci0: Device booted in 15680 usecs
*[   32.409513] Bluetooth: hci0: Found Intel DDC parameters:
intel/ibt-0040-0041.ddc*
[   32.412401] Bluetooth: hci0: Applying Intel DDC parameters completed
*[   32.415476] Bluetooth: hci0: Firmware timestamp 2023.28 buildtype 1
build 68350*
[   32.415482] Bluetooth: hci0: Firmware SHA1: 0xc64314a8
[   32.587297] Bluetooth: hci0: Bad flag given (0x1) vs supported (0x0)
[   32.587398] Bluetooth: hci0: Bad flag given (0x1) vs supported (0x0)
[   32.587484] Bluetooth: hci0: Bad flag given (0x1) vs supported (0x0)
[   32.587627] Bluetooth: hci0: Bad flag given (0x1) vs supported (0x0)

Bluetooth keyboard, mouse and headphones connected automatically. I then
proceeded to play some music in Spotify which in my experience shortens the
time until the disconnection issue happens.

Sure enough after less than 1 minute I started hearing bluetooth sound
hiccups which indicate a problem with the bluetooth connection. These
repeat occasionally.
***However**, *the devices DID NOT disconnect even after 1 hour of
continuous use and I did not see the error message I did with the newer
firmware:

kernel: Bluetooth: hci0: Hardware error 0x0c

So this is already some improvement. What I can also try is to downgrade
the kernel from the HWE version (6.8) to the GA version (5.15) and see if
that helps. I'll try that later once I have a grip I know what I'm doing :-)




On Sat, 19 Jul 2025 at 16:36, Tal Lichtenstein <tal.lich@gmail.com> wrote:

> I think this is not the same bug as 220341 - that bug reports the stack
> crashing and Bluetooth becoming disabled. This is not the case here - it
> just causes devices to disconnect periodically. I suspect the firmware is
> crashing and restarting but have no way to verify this. I will try however
> to switch to some older firmware and see if this stops. Will report the
> results.
>
> On Sat, Jul 19, 2025, 15:06 <bugzilla-daemon@kernel.org> wrote:
>
>> https://bugzilla.kernel.org/show_bug.cgi?id=220344
>>
>> --- Comment #2 from Paul Menzel (
>> pmenzel+bugzilla.kernel.org@molgen.mpg.de) ---
>> Was the Linux firmware updated on your system, so you actually need to
>> test an
>> *older* firmware version?
>>
>> --
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