bluetooth low energy devices stopped working on newer linux kernels (6.4) #242313

Closed MangoIV closed 10 months ago

Describe the bug

For a while not I cannot pair any bluetooth keyboards anymore, the keyboards have been confirmed to work fine by connecting to another central device.

Steps To Reproduce

nixos version is 23.05
try to connect via bluetoothctl
- scan on
- scan off
- agent on
- default-agent
- connect <MAC address>
- tries to connect and pair but then immediately aborts

Expected behavior

the keyboard connects and pairs fine

Screenshots

Additional context

everything to do with bluetooth has been incredibly unstable, stuff randomly stops working, there are hard to reproduce bugs and failures all over the place, the tooling is not well documented and so on. I know this is not a NixOS issue per se but it would be nice if we could do something about it. If anybody had any input on how other Linux distribution deal with bluetooth stacks to be stable and nice to use, that would be really awesome.
My entire configuration can be found at https://git.sr.ht/~mangoiv/dotfiles/tree/dad63d0984033c7a9e55b107848359420353ce37

Metadata

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 6.4.1-zen1, NixOS, 23.11 (Tapir), 23.11.20230706.3c74875`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix Super) 2.14.0pre20230128_792d83f`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

I had a similar problem where bluetooth LE stopped working and I couldn't find my keyboard. I was also running kernel version 6.4. Downgrading the kernel to 6.1 solved it for me.

Thank you for that information, do you know what specifically causes this behaviour?

Sadly not. I couldn't find any good error logs/messages and couldn't find anything relevant on the kernels bugzilla. What I can say is that this problem was replicated on two different devices (HP Elitebook and Dell Precision) both running NixOS on the latest kernel, downgrading to 6.1 helped on both.

Also other bluetooth devices worked, seems to be isolated to just LE devices. So most likely some bug in Bluez kernel modules for LE?

Did downgrading help you?

No, though I haven’t tried yet - should do that - I mean it’s not a long term solution but it might resolve the issue for now.

Most likely related to https://bugzilla.kernel.org/show_bug.cgi?id=217651

Seems to be a patch in the pipeline so let's hope it is related so we can return to the latest kernel version :)

It now works for me with the latest kernel version 6.4.9 (nixpkgs rev ce5e4a6ef2e59d89a971bc434ca8ca222b9c7f5e)

Nice thank you for the heads up!

I can't pair my bluetooth 5.0 mouse anymore and that patch/thing doesn't seem like it helped ...

Yes for me too, had to downgrade to 6.1 again.

I have tested opensuse's live cd iso and the issue is present there too. Someone has to report this on kernel.org

this is not present for all bluetooth LE devices apparently, I have a pointing device that is working just fine, whereas my keyboard with ZMK firmware doesn't I'm starting to think this might be an issue with the clients bluetooth stack, perhaps zephyros

Can chime in with when I had this problem it was also with a keyboard running ZMK firmware

Alright. Maybe it's not a kernel problem after all

@kelszo there might be fix for you https://github.com/zmkfirmware/zmk/issues/1487#issuecomment-1836675169

Thanks for the tip @MangoIV. I also use a Keyboard with ZMK (Kinesis Adv360) on NixOS (kernel 6.6.3) and can chime in and say that the fix https://github.com/zmkfirmware/zmk/issues/1487#issuecomment-1836675169 worked for me. I can finally use the Adv360 via Bluetooth. (I also had to use bluetuith to actually pair the Keyboard if that helps as bluetoothctl didn't work)

I think it's pretty clear by now that this issue is caused by ZMK. If you run into this issue, please refer to the discussion above which should solve your problems.

@kelszo there might be fix for you zmkfirmware/zmk#1487 (comment)

Thank you, finally found what's causing the issue after days of research. I can confirm that after enabling the experimental features for ZMK does indeed fix the problem.

NixOS / nixpkgs