How to debug Bluetooth problems

Bluetooth is a short range wireless protocol that is used to connect to various low bandwidth I/O devices (like keyboards, mice, headsets). Newer versions have a low-energy mode with a slightly higher bandwidth and range.

The Bluetooth solution is composed of a userspace daemon, bluetoothd, that communicates through a management port in the kernel to the hardware drivers. Applications that want to communicate with the bluetoothd daemon do so over a d-bus api. This includes the various GNOME bluetooth applets.

Identifying Bluetooth Problems

Was the bluetooth hardware found?

• Make sure bluetooth was found and enabled (note hci0: and 'UP RUNNING'):

  $ hciconfig
  hci0:	Type: Primary  Bus: USB
  	BD Address: xx:xx:xx:xx:xx:xx  ACL MTU: 1021:4  SCO MTU: 96:6
  	UP RUNNING PSCAN 
  	RX bytes:15047 acl:0 sco:0 events:2433 errors:0
  	TX bytes:599323 acl:0 sco:0 commands:2431 errors:0
  

• If the command returns nothing (no hci: info), then there is a hardware issue

  $ lsusb -v | grep Bluetooth | grep DeviceProtocol
  bDeviceProtocol         1 Bluetooth
  

• If the lsusb command returns nothing, there is no hardware, a dmesg output would be needed
• If the lsusb commands returns Bluetooth, then check for attached driver

  $ lsusb -t | grep Wireless
      |__ Port 4: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
      |__ Port 4: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
  

• If Driver is empty, lsusb -v output would be needed to add ids
• If hciconfig shows output but not UP

  $ hciconfig up 

Is the bluetoothd daemon running?

• Verify under systemd bluetooth is 'Active' and 'enabled'

  $ systemctl status bluetooth
  ● bluetooth.service - Bluetooth service
     Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2017-10-04 16:07:40 EDT; 1 day 22h ago
       Docs: man:bluetoothd(8)
   Main PID: 27427 (bluetoothd)
     Status: "Running"
      Tasks: 1 (limit: 4915)
     CGroup: /system.slice/bluetooth.service
             └─27427 /usr/libexec/bluetooth/bluetoothd
  

• Verify obex is configured to run (to transfer files from phone)

  $ systemctl --global --user is-enabled obex
  enabled
  

Simple debugging

Most bluetooth problems happen in the bluez package (bluetoothd), ie the userspace daemon.

• Enabling bluetoothd debugging

  $ \<edit\> /usr/lib/systemd/system/bluetooth.service
  \<add '-d' to ExecStart line as option to bluetoothd\>
  \<save and quit\>
  $ systemctl daemon-reload
  $ systemctl restart bluetoothd
  

  Debugging is enabled and can help pinpoint where some of the bluetooth problems are

• Capture the logs to put in bugzilla report

  $ journalctl -r -u bluetooth > /tmp/bluetoothd.out