Created attachment 610633 [details]
Xorg.0.log

On the same system where I experienced bug 899501, I've updated the system to a
later Factory build and can now no longer activate my external display at all.

Though xrandr reports:
Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
eDP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x
175mm
   1920x1080     60.01*+
   1400x1050     59.98  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32    56.25  
   640x480       59.94  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
DP4 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 546mm x
352mm
   1920x1200     59.95*+
   1920x1080     59.99  
   1600x1200     60.00  
   1680x1050     59.95  
   1280x1024     60.02  
   1440x900      59.89  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       60.00  
DP5 disconnected (normal left inverted right x axis y axis)


The output on DP4 is black, and the monitor does not detect a signal.