Bluetooth

Bluetooth is a standard for the short-range wireless interconnection of cellular phones, computers, and other electronic devices. In Linux, the canonical implementation of the Bluetooth protocol stack is BlueZ.
== Pairing ==
phone:~# service bluetooth start
phone:~# bluetoothctl
Agent registered
[CHG] Controller XX:XX:XX:XX:XX:XX Pairable: yes
[bluetooth]# scan on
[NEW] 00:11:22:33:44:55
[bluetooth]# pair 00:11:22:33:44:55
To use bluetooth headphones with pulseaudio, the package is required.
== Supported Bluetooth Profiles ==
=== Audio/Video Remote Control Profile (AVRCP) ===
To use media keys with Bluetooth, the mpris-proxy command should be run. It needs access to Dbus.
mpris-proxy is started at boot to enable AVRCP 1.5 support. PulseAudio and BlueZ must be installed for this which pulls in mpris-proxy automatically.
MR at pmaports: 
=== Advanced Audio Distribution Profile (A2DP) ===
PulseAudio and BlueZ handle together Bluetooth A2DP 1.3 support.
This is supported out-of-the-box.
=== PhoneBook Access Profile (PBAP) ===
BlueZ got PBAP 1.1 support recently in 5.63 with GNOME Evolution as backend.
Currently, a MR is pending at Alpine to enable this feature: https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/29955
=== Object Push Profile (OPP) ===
OBEXd was enabled at boot to enable OPP 1.2 support for transfering and receiving files over Bluetooth.
MR at pmaports: 
=== Human Interface Device Profile (HID) ===
BlueZ provides the HID 1.0 profile to support mice and keyboards over Bluetooth.
It is enabled by default.
== Unsupported Bluetooth Profiles ==
=== Message Access Profile (MAP) ===
BlueZ has support for MAP 1.0 but does not have a backend which is compatible with any UI stack.
The supported backends are from the old Nokia Maemo days.
=== Personal Area Network (PAN) ===
BlueZ supports PAN 1.0. You should be able to use PAN network using NetworkManager. Make sure you have the networkmanager-bluetooth package, which is not there by default at the time of writing this sentence.
To connect to a shared connection using Bluetooth, desktop environments like Plasma should let you create a network manager connection automatically, but you can also do it manually: create a /etc/NetworkManager/system-connections/MyConnectionName.nmconnection with a content that looks like this:
 [connection]
 id=MyConnectionName
 uuid=UUID
 type=bluetooth
 autoconnect=false
 metered=1
 
 [bluetooth]
 bdaddr=BDADDR
 type=panu
 
 [ipv4}
 method=auto
 
 [ipv6]
 addr-gen-mode=default
 method=auto
 
 [proxy]
Where UUID is a uuid you can generate using uuidgen, and BDADDR is the Bluetooth address of your access point.
You can also try something like this:
 nmcli connection add type bluetooth con-name "Bluetooth Hotspot" autoconnect no ifname btnap0 bluetooth.type nap ipv4.method shared ipv6.method disabled
For now, only IPv4 is marked as shared. IPv6 should work but was not tested.
This works if BlueZ was built with BNEP support and a valid Bluetooth MAC address is available.
Without a valid MAC address, the BlueZ BNEP network bridges cannot be added to the kernel.
Source: https://networkmanager.dev/docs/api/latest/nmcli-examples.html
=== Hands-Free Profile (HFP) ===
BlueZ and PulseAudio partly support HFP 1.6. Only the audio part is supported.
Reporting battery levels from the AG to HF is unsupported and all cellular operations and status reporting is not supported (yet).
A first step in fully supporting Bluetooth HFP 1.6 is taken here: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/631
postmarketOS edge has the necessary patches applied to PulseAudio for supporting Bluetooth HFP AT commands (battery level reporting, cellular status, accept/reject calls, etc.), audio routing not yet.
Feedback is welcome in https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/693
HFP AT command support for controlling calls is merged in PipeWire and will be available officially when postmarketOS switches to PipeWire in the near future.
=== Other profiles ===
Bluetooth supports many other profiles, see https://www.bluetooth.com/specifications/
It is currently unknown if they are supported or not.
== Bluetooth profiles supported by other mobile OSes ==
 Supported Bluetooth profiles by Apple: https://support.apple.com/en-us/HT204387
 Supported Bluetooth profile by Android: https://source.android.com/devices/bluetooth/services
== Troubleshooting ==
=== No default controller available ===
# modprobe -r btqcomsmd
# modprobe btqcomsmd
Failed set serial line discipline: Invalid argument in btattach or Can't set line discipline: Invalid argument in hciattach:
Enable CONFIG_BT_HCIUART (and possibly CONFIG_BT_HCIUART_BCM) in kernel config.
btattach -P bcm doesn't set desired baud rate after uploading firmware:
Use hciattach instead (https://github.com/Arkq/bluez-alsa/issues/205) and verify results with stty -F /dev/tty.
=== Failed to start discovery: org.bluez.Error.NotReady or Failed to connect: org.bluez.Error.NotReady br-connection-adapter-not-powered ===
[bluetooth]# power on
Changing power on succeeded
[CHG] Controller XX:XX:XX:XX:XX:XX Powered: yes
=== Failed to connect: org.bluez.Error.Failed br-connection-profile-unavailable ===
When connecting to a headset.
# apk add bluez-alsa
# service bluealsa start
# bluetoothctl
[bluetooth]# connect 00:11:22:33:44:55
Attempting to connect 00:11:22:33:44:55
Connection successful
[CHG] Device 00:11:22:33:44:55 ServicesResolved: yes
=== Bluetooth keyboards, mice and other HID devices ===
==== With UHID ====
First, install hidapi:
# apk add hidapi
Make sure CONFIG_UHID is enabled in your kernel. If it's enabled as a module, run:
# modprobe uhid
# service bluetooth restart
Getting the device to work might require a few tries; in general, what often works is first pairing the device, then turning off Bluetooth, turning it on again and letting the device connect again (many mice/keyboards will try to reconnect when you press any key/move the mouse).
==== Without UHID ====
Open /etc/bluetooth/input.conf, and configure it:
[General]
# Enable HID protocol handling in userspace input profile
# Defaults to true (Use UHID instead of kernel HIDP)
UserspaceHID=false
Note that the default value was false until 5.73input.conf: Make UserspaceHID defaults to true.
Restart service bluetooth.
# service bluetooth restart
=== DUALSHOCK 4 / DualSense ===
Disconnection of PlayStation controllers has been addressed in bluez#614. The fixinput: Fix .device_probe failing if SDP record is not found to the issue has been released in 5.71+.
== References ==
Category:Technical Reference