11

I recently updated from Ubuntu 18.04.4 to 20.04.1 on a Lenovo T400 2765. When I connected an external Fujitsu Siemens P19-1A monitor via VGA it is shown as "Unknown Display" in Settings > Displays. This was not the case in Ubuntu 18.04.4.

Screenshot of Settings > Displays

Also, the native resolution (1280x1024) is not available.

Here is what xrandr tells about the monitors:

$ xrandr --listmonitors
Monitors: 2
 0: +XWAYLAND0 1440/300x900/190+0+768  XWAYLAND0
 1: +XWAYLAND1 1024/271x768/203+0+0  XWAYLAND1

...

$ xrandr
Screen 0: minimum 16 x 16, current 1440 x 1668, maximum 32767 x 32767
XWAYLAND0 connected 1440x900+0+768 (normal left inverted right x axis y axis) 300mm x 190mm
   1440x900      60.03*+
XWAYLAND1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768      59.92*+

There is no additional drivers installed:

Screenshot of Software & Updates > Additional Drivers

How can I make Ubuntu recognize the monitor? Is there a driver in Ubuntu 18.04.4 which I have to manually install?

I found this very good article on how to add a custom resolution but I would prefer to let Ubuntu recognize the actual monitor (brand/model) as before.

Related

Improve this question
2
  • Lenovo P1 has the same issues
    – ignacio
    Jun 21, 2022 at 7:46
  • First make sure your cable works properly 😅 My problem solved by changing the VGA cable!
    – Daniyal Javani
    Nov 1, 2023 at 14:25

1 Answer 1

Reset to default
1

Follow these steps:

  1. Locate monitors.xml, usually in /home/username/.config/monitors.xml.

  2. Then find the name of unknown display inside <connector>DP-1</connector>.

  3. Open GRUB using nano:

    sudo nano /etc/default/grub

    or, if you prefer a GUI application such as gedit:

    gksudo gedit /etc/default/grub

  4. Change the line starting with GRUB_CMDLINE_LINUX= to include the name of the unknown display you found in step 2 as follows:

    GRUB_CMDLINE_LINUX="video=DP-1:d"

  5. Save the changes in nano by Ctrl+O and Enter and close the editor by Ctrl+X and Enter (if you used a GUI editor just save as usually and close the editor).

  6. Update GRUB:

    sudo update-grub
Improve this answer
2
  • I had a look into ~/.config/monitors.xml. There is no entry named DP-1. How do I recognize the right one?
    – JJD
    May 1, 2022 at 11:59
  • The step 4 isn't clear for me. Where is the name supposed to be added? I could solve my issue by using the command GRUB_CMDLINE_LINUX="video=DP-1:d" without any name.
    – ignacio
    Jun 21, 2022 at 7:49

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .