I'm running Xubuntu 21.04 on a Dell Latitude 7390 with a Dell D6000 dock. As of a recent update, the laptop stops being responsive if I disconnect it from the dock. It does not become responsive again after being connected; I am forced to reboot. Similarly, when booting from cold without the dock connected, the laptop freezes shortly after showing the Xubuntu login dialogue. This makes me believe the issue is not necessarily related to this known issue: The X server may crash after unplugging a DisplayLink device, if the device was the only active screen.
These are the last messages recorded in /var/log/syslog after disconnecting the dock.
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.622355] usb 3-1: USB disconnect, device number 2
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.622367] usb 3-1.2: USB disconnect, device number 3
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.622373] usb 3-1.2.3: USB disconnect, device number 10
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.691901] xhci_hcd 0000:3b:00.0: xHCI host controller not responding, assume dead
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.692007] xhci_hcd 0000:3b:00.0: HC died; cleaning up
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.733532] usb 4-1: USB disconnect, device number 2
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.733554] usb 4-1.1: USB disconnect, device number 3
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.737007] cdc_ncm 4-1.1:1.5 enx9cebe89243f5: unregister 'cdc_ncm' usb-0000:3b:00.0-1.1, CDC NCM
Jun 14 10:12:06 hbotha-Latitude-7390 pulseaudio[8156]: Got POLLNVAL from ALSA
Jun 14 10:12:06 hbotha-Latitude-7390 pulseaudio[8156]: Got POLLNVAL from ALSA
Jun 14 10:12:06 hbotha-Latitude-7390 org.kde.kdeconnect[10376]: org.kde.pulseaudio: No object for name "alsa_output.usb-DisplayLink_Dell_Universal_Dock_D6000_1809148265-02.iec958-stereo"
Jun 14 10:12:06 hbotha-Latitude-7390 org.kde.kdeconnect[10376]: org.kde.pulseaudio: No object for name "alsa_output.usb-DisplayLink_Dell_Universal_Dock_D6000_1809148265-02.iec958-stereo"
Jun 14 10:12:06 hbotha-Latitude-7390 org.kde.kdeconnect[10376]: org.kde.pulseaudio: No object for name "alsa_input.usb-DisplayLink_Dell_Universal_Dock_D6000_1809148265-02.iec958-stereo"
Jun 14 10:12:06 hbotha-Latitude-7390 NetworkManager[791]: <info> [1623658326.5202] device (enx9cebe89243f5): state change: unavailable -> unmanaged (reason 'removed', sys-iface-state: 'removed')
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.759109] xhci_hcd 0000:3b:00.0: remove, state 1
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.759115] usb usb4: USB disconnect, device number 1
Jun 14 10:12:06 hbotha-Latitude-7390 acpid: input device has been disconnected, fd 22
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.783040] usb 4-1.2: USB disconnect, device number 4
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.783772] xhci_hcd 0000:3b:00.0: USB bus 4 deregistered
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.783787] xhci_hcd 0000:3b:00.0: remove, state 1
Jun 14 10:12:06 hbotha-Latitude-7390 kernel: [ 636.783789] usb usb3: USB disconnect, device number 1
Jun 14 10:12:06 hbotha-Latitude-7390 systemd[1]: Stopped DisplayLink Driver Service.
Any ideas for how I could debug this?
EDIT: Per request, here's some dmesg output.
2021-06-14 16:22:27 hbotha ~dev
» sudo dmesg | rg -i 'error'
[ 5.675152] RAS: Correctable Errors collector initialized.
[ 5.893261] intel-lpss: probe of INT3446:00 failed with error -16
[ 6.934604] EXT4-fs (sda5): re-mounted. Opts: errors=remount-ro. Quota mode: none.
