xrandr three monitors

Question

Im using Fedora 24 with 2 additional non HDPI dell monitors with my HDPI laptop (using thunderbolt 3 and daisy chaining the monitors with DP1.2)

I am trying to get the 3 monitors to display nicely with sizing. So far I've managed to get the laptop and 2nd monitor working correctly with the following command:

xrandr --output eDP-1 --auto --output DP-1-8 --auto --panning 3840x2400+3840+0 --scale 2x2 --right-of eDP-1

however I can't seem to get the 3rd monitor to display anything useful, attempting with this command xrandr --output eDP-1 --auto --output DP-1-8 --auto --panning 3840x2400+3840+0 --scale 2x2 --right-of eDP-1 --output DP-1-1-8 --auto --panning 3840x2400+3840+0 --right-of DP-1-8
 has resulted in the 3rd monitor tracking part of the second screen very zoomed in. I think I myust have the scale/panning off.

Can anyone help me get this set up corerctly?

see display setup below:

$ xrandr
Screen 0: minimum 320 x 200, current 7680 x 2400, maximum 8192 x 8192
eDP-1 connected primary 3840x2160+0+0 (normal left inverted right x axis y axis) 346mm x 194mm
   3840x2160     60.00*+
   2048x1536     60.00  
   1920x1440     60.00  
   1856x1392     60.01  
   1792x1344     60.01  
   1600x1200     60.00  
   1400x1050     59.98  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   800x600       60.00    60.32    56.25  
   700x525       59.98  
   640x512       60.02  
   640x480       60.00    59.94  
   512x384       60.00  
   400x300       60.32    56.34  
   320x240       60.05  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-1-8 connected 3840x2400+3840+0 (normal left inverted right x axis y axis) 518mm x 324mm panning 3840x2400+3840+0
   1920x1200     59.95*+
   1920x1080     60.00    50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DP-1-1-8 connected 3840x2400+3840+0 (normal left inverted right x axis y axis) 518mm x 324mm panning 3840x2400+3840+0
   1920x1200     59.95*+
   1920x1080     60.00    50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1600x1200     60.00  
   1280x1024     75.02    60.02  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DP-1-1-1 disconnected (normal left inverted right x axis y axis)
DP-1-1 disconnected (normal left inverted right x axis y axis)

przemo_li · Answer

xrandr --output eDP-1 --auto --output DP-1-8 --auto --panning 3840x2400+3840+0 --scale 2x2 --right-of eDP-1 --output DP-1-1-8 --auto --panning 3840x2400+ 3840 +0 --right-of DP-1-8

Is that value correct?
Your first screen will start at x = 0, second at x = 3840, and third at x = 3840 basically displaying same content as 2nd one.

Try:

xrandr --output eDP-1 --auto --output DP-1-8 --auto --panning 3840x2400+3840+0 --scale 2x2 --right-of eDP-1 --output DP-1-1-8 --auto --panning 3840x2400+ 7680 +0 --right-of DP-1-8

Then 3rd one will start just after 2nd one ends.

rudimeier · Answer

I'm not very familiar with xrandr that's why I usually would start with a simple fixed setup in /etc/X11/xorg.conf, like this for your case:

Section "Monitor"
  Identifier "ONE"
  Option "PreferredMode"  "3840x2160"
  Option "Position" "0 0"
  Option "Primary" "true"
EndSection

Section "Monitor"
  Identifier "TWO"
  Option "PreferredMode"  "1920x1200"
  Option "Position" "3840 0"
  Option "RightOf" "ONE"
  Option "Primary" "true"
EndSection

Section "Monitor"
  Identifier "THREE"
  Option "PreferredMode"  "1920x1200"
  Option "Position" "5760 0"
  Option "RightOf" "TWO"
  Option "Primary" "true"
EndSection

Section "Device"
  Identifier  "intel-id"
  Driver "intel"
  Option "monitor-eDP-1" "ONE"
  Option "monitor-DP-1-8" "TWO"
  Option "monitor-DP-1-1-8" "THREE"
EndSection

Restart X server, and if ok, try to add the other panning and scale options etc.

At the and you may try to translate the xorg.conf back into a xrand command line. I know actually it would be better to do it the other way around but this way is easier for me.

xrandr three monitors

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