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screens keep switching display port names/numbers – how to configure settings?

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Paŭlo Ebermann

I have a notebook (Lenovo Thinkpad T14) running Ubuntu 21.10 (and another similar one running Ubuntu 20.4) with Xfce4 (aka XUbuntu) and a Thinkpad USB-C docking station, to which I've connected two external screens. I'm using one of them in a vertical direction, the other one horizontally, in addition to the Notebook screen.

Unfortunately, each time I start the system (and occasionally also when I disconnect and then reconnect the docking station), the assignment of the screens to the display port numbers are different, and thus the previously saved screen arrangement does not work anymore. Some assignments I've found:

  • vertical on DisplayPort-5, horizontal on DisplayPort-6
  • vertical on DisplayPort-5, horizontal on DisplayPort-3
  • vertical on DisplayPort-3, horizontal on DisplayPort-4
  • vertical on DisplayPort-3, horizontal on DisplayPort-5
  • vertical on DisplayPort-6, horizontal on DisplayPort-5

Once I even got a seventh display port, though that might have been when I tried out a second docking station in addition.

My current solution is to store a profile in the display settings (each time I hit a new one I didn't get before, I add it there). When the screens are wrong after login:

  1. switch off the power (to screens and docking station), which disconnects all screens
  2. switch the power on again → then the "Screens" dialog pops up:(screens dialog image)
  3. try the buttons until one of them arranges the screens the right way
  4. If none of them fits, create a new setup (and call up arandr to get the names of the displays).

I recently found out that on my Thinkpad keyboard I can also use the Fn+F7 key to get the dialog, so I don't have to switch the power off and on.

Still, is there some way of automating this, so I get the screens arranged correctly without manual input each time?

Some details:

As an example, when I originally wrote the question, xrandr -q printed this:

Screen 0: minimum 320 x 200, current 3000 x 1275, maximum 16384 x 16384
eDP connected 1280x720+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1920x1080     60.05 +
   1680x1050     60.05  
   1280x1024     60.05  
   1440x900      60.05  
   1280x800      60.05  
   1280x720      60.05* 
   1024x768      60.05  
   800x600       60.05  
   640x480       60.05  
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 disconnected (normal left inverted right x axis y axis)
DisplayPort-4 disconnected (normal left inverted right x axis y axis)
DisplayPort-5 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080     60.00*+
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   720x400       70.08  
DisplayPort-6 connected 1920x1080+1080+195 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   640x480       75.00    72.81    66.67    59.94  
   720x400       70.08  
DVI-I-4-4 disconnected (normal left inverted right x axis y axis)
DVI-I-3-3 disconnected (normal left inverted right x axis y axis)
DVI-I-2-2 disconnected (normal left inverted right x axis y axis)
DVI-I-1-1 disconnected (normal left inverted right x axis y axis)

So the screens were connected to "DisplayPort-5" and "DisplayPort-6".

I then switched off the computer, switched it on again, and the screens were messed up (overlapping view ports). xrandr -q showed this:

Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
eDP connected 1280x720+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
   1920x1080     60.05 +
   1680x1050     60.05  
   1280x1024     60.05  
   1440x900      60.05  
   1280x800      60.05  
   1280x720      60.05* 
   1024x768      60.05  
   800x600       60.05  
   640x480       60.05  
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080     60.00*+
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   720x400       70.08  
DisplayPort-4 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   640x480       75.00    72.81    66.67    59.94  
   720x400       70.08  
DVI-I-4-4 disconnected (normal left inverted right x axis y axis)
DVI-I-3-3 disconnected (normal left inverted right x axis y axis)
DVI-I-2-2 disconnected (normal left inverted right x axis y axis)
DVI-I-1-1 disconnected (normal left inverted right x axis y axis)

So the screens are now recognized as "DisplayPort-3" and "DisplayPort-4", not 5 and 6 as before.

After triggering the screen setup dialog and choosing the correct one (vDP3+hDP4+laptop, the second custom one in the screenshot above), it shows this (I'm not sure whether it shows how one is rotated):

Screen 0: minimum 320 x 200, current 3000 x 1996, maximum 16384 x 16384
eDP connected 1280x720+1080+1276 (normal left inverted right x axis y axis) 309mm x 174mm
   1920x1080     60.05 +
   1680x1050     60.05  
   1280x1024     60.05  
   1440x900      60.05  
   1280x800      60.05  
   1280x720      60.05* 
   1024x768      60.05  
   800x600       60.05  
   640x480       60.05  
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 connected 1080x1920+0+0 left (normal left inverted right x axis y axis) 509mm x 286mm
   1920x1080     60.00*+
   1600x900      60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   640x480       75.00    59.94  
   720x400       70.08  
DisplayPort-4 connected 1920x1080+1080+196 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1440x900      59.90  
   1280x960      60.00  
   1280x800      59.91  
   1152x864      75.00  
   1280x720      60.00  
   1024x768      75.03    70.07    60.00  
   832x624       74.55  
   800x600       72.19    75.00    60.32    56.25  
   640x480       75.00    72.81    66.67    59.94  
   720x400       70.08  
DVI-I-4-4 disconnected (normal left inverted right x axis y axis)
DVI-I-3-3 disconnected (normal left inverted right x axis y axis)
DVI-I-2-2 disconnected (normal left inverted right x axis y axis)
DVI-I-1-1 disconnected (normal left inverted right x axis y axis)
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kanehekili avatar
zw flag
kanehekili
it looks like that the display port names change (which shouldn't), but to prove it you should copy the contents of `xandr -q` from the current configuration and , when changed, from the next configuration. Compare the both or add them to your question. The "names" should sth like "dpms1"
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in flag
Paŭlo Ebermann
@kanehekili yes, they do change the names – that's what I meant to indicate with my list. I've added the output from before and after switching off (and on) the computer.
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kanehekili avatar
zw flag
kanehekili
Looks like that this is below X11. My deleted suggestion to write a X11 conf file is futile. In arch linux it might be [fixable](https://www.reddit.com/r/archlinux/comments/mrb6ea/xorg_output_names_changing_on_reboots/)
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rijotech avatar
ss flag
rijotech
I'm facing a similar problem, have you found a solution yet?
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in flag
Paŭlo Ebermann
@rijotech No, this still happens.
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mars8 avatar
fo flag
mars8
i am also having this problem. does anybody know good resources for configuring multi-monitor set up with bash?
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