Getting bluetooth to work on Pi 4B

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1

Hi,
I’ve been trying to get bluetooth to work on my Raspberrry Pi model 4B under Nixos (24.11) for some time, but am having no luck. I’m using this kernel param:

    kernelParams = [ "console=tty0,115200n8" ];

together with these settings:

hardware = {
    bluetooth.enable = true;
    bluetooth.powerOnBoot = true;
    enableRedistributableFirmware = true;
};

I set the kernel param because it appeared that Nixos was spawning a console on the same tty which apparently hosts bluetooth (ttyAMA0).

bluetoothctl power on gives No default controller available and dmesg shows

[   13.596584] Bluetooth: hci0: command 0xfc18 tx timeout
[   13.601881] Bluetooth: hci0: BCM: failed to write update baudrate (-110)
[   13.608676] Bluetooth: hci0: Failed to set baudrate
[   15.644618] Bluetooth: hci0: command 0xfc18 tx timeout
[   15.650001] Bluetooth: hci0: BCM: Reset failed (-110)
[   31.452582] Bluetooth: hci1: command 0x0c03 tx timeout
[   31.457791] Bluetooth: hci1: BCM: Reset failed (-110)

There’s some history to this problem: NixOS on Raspberry Pi 4 Model B | bluetoothctl issue: No default controller available · Issue #123725 · NixOS/nixpkgs · GitHub

I’ve tried a bunch of things listed in this issue, but switching the tty had no effect and changing the kernel packages to the pi ones leads to an unbootable system.

I’d really appreciate any tips or tricks to get this to work, because it can: when I used to run the pi off of a home-assistant image bluetooth worked. I just need to find the right config.

The entire config is here: GitHub - mdirkse/akkad: NixOS configuration of my home automation system

Regards,
Maarten

2

Please look through my last post in that thread. Bluetooth continues to work well for me (I’m not following nixpkgs-unstable).

I think using the Pi kernel might have been the key piece. You should investigate why it gives you an unbootable system.

3

Hey, thanks for the reply. Just tried it again with boot.kernelPackages = pkgs.linuxKernel.packages.linux_rpi4;. I hadn’t changed the TTY when I tried that the first time, so I thought it might work now, but it didn’t. The system shows the Pi startup screen, then shows these lines:

EFI stub: Booting Linux Kernel
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path
EFI stub: Generating empty DTB
EFI stub: Exiting boot services...

And then hangs. There’s nothing in the system log or dmesg as far as I can tell, as it hangs when trying to start the kernel (I think). I’ll investigate a bit more to see if I can get it to print something about why it’s not making any progress.

Regards,
Maarten

4

What bootloader are you using?

5

I’m using systemd-boot (if I’m not mistaken).

6

I haven’t installed the UEFI firmware from the link in your response to the issue (GitHub - pftf/RPi4: Raspberry Pi 4 UEFI Firmware Images). I suppose that’s a prerequisite as well?

Regards,
Maarten