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I have a Dell D6000 docking station which I am using with an Ubuntu 20.04 laptop.

At present only the HDMI output is working, the displayport outputs does not work as intended (it does not detect the monitor is connected and provides not output to the screen). If possible I would like to know how to rectify this?

xrandr output:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 380mm x 210mm
   1920x1080     60.00*+  59.93    48.07  
   1680x1050     59.88  
   1600x1024     60.17  
   1400x1050     59.98  
   1600x900      60.00    59.95    59.82  
   1280x1024     60.02  
   1440x900      59.89  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1368x768      60.00    59.88    59.85  
   1360x768      59.80    59.96  
   1280x800      59.81    59.91  
   1152x864      60.00  
   1280x720      59.86    60.00    59.74  
   1024x768      60.00  
   1024x576      60.00    59.90    59.82  
   960x540       60.00    59.63    59.82  
   800x600       60.32    56.25  
   864x486       60.00    59.92    59.57  
   640x480       59.94  
   720x405       59.51    60.00    58.99  
   640x360       59.84    59.32    60.00  
DP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 530mm x 300mm
   1920x1080     60.00*+  50.00    59.94  
   1680x1050     59.88  
   1600x900      60.00  
   1280x1024     60.02  
   1440x900      59.90  
   1280x800      59.91  
   1280x720      60.00    50.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       60.00    59.94  
   720x400       70.08  
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)

I appreciate that the above output lists HDMI1 + HDMI2 as disconnected but DP-1 as connected however I can guarantee the HDMI cable is the one connected from the dock to the working monitor (I have checked numerous times thinking I was going mad). Removing either of these cables causes the display to shut off and a restart is required to get it working again. Swapping the display port cable over to the other port does not change the xrandr output and unplugging the HDMI cable leaves DP1 showing as disconnected.

Output of cat /etc/X11/xorg.conf.d/20-displaylink.conf:

Section "Device"
Identifier "intel"
Driver "modesetting"
Option "kmsdev" "/dev/dri/card0"
Option "PageFlip" "off"
Option "SWCursor" "on"
Option "ShadowFB" "true"
EndSection

Section "Device"
Identifier "USB3"
BusID "USB"
Driver "modesetting"
Option "kmsdev" "/dev/dri/card1"
Option "PageFlip" "off"
Option "SWCursor" "on"
Option "ShadowFB" "true"
EndSection

Section "Device"
Identifier "USB3"
BusID "USB"
Driver "modesetting"
Option "kmsdev" "/dev/dri/card2"
Option "PageFlip" "off"
Option "SWCursor" "on"
Option "ShadowFB" "true"
EndSection

Section "Device"
  Identifier "DisplayLink"
  Driver "modesetting"
  Option "PageFlip" "false"
EndSection  

Output of xrandr --listmonitors:

Monitors: 2
 0: +*eDP1 1920/380x1080/210+0+0  eDP1
 1: +DP1 1920/530x1080/300+0+0  DP1

If there is anything else I can do to gather information about this issue please let me know. The only fix I can think of for this is to try and force output down the HDMI ports and see if one of them starts working with the monitor. Are there any better solutions available?

2 Answers 2

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Ensure secure boot is turned off in the BIOS (I also enabled legacy support - not sure if this is required)

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Disabling secure boot following this procedure worked for me, thanks user1102370

Specific steps:

Completely shut down your laptop.

Power on the system and as soon as the first logo screen appears, immediately press F2 to enter the BIOS.

Use the right arrow key to select Security tab.

Use the down arrow key to highlight Set Supervisor Password and press Enter.

Type some password and press Enter. Don't forget the password you enter!

Retype the password to confirm and press Enter again.

Use the right arrow key to select Boot tab.

Press the down arrow key to select Secure Boot and press Enter.

With the arrow key, highlight Disabled and press Enter.

Press the F10 key and select Yes to save the changes and exit the BIOS.

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  • While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - From Review Oct 5, 2021 at 23:09
  • Sure, essential part added
    – JB Rolland
    Oct 6, 2021 at 21:38

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