Archive for May 6th, 2015

Rebooting a Dell U2711 Monitor

It turns out my fancy Dell U2711 landscape monitor doesn’t work well with Displayport video. I normally leave it in power-save mode, with the power LED slowly fading orange, but about once a week it won’t start up when I turn on the PC. It seems the only solution is a hard power cycle, so I plugged it into a remotely switched outlet to eliminate having to pull its plug.

Now that I know what to watch for, it’s easy to work around: if the power LED doesn’t turn blue when the PC power goes on, immediately turn off the PC power and power-cycle the U2711. If I let the PC continue in Xubuntu, the U2713 portrait monitor becomes the primary display and X helpfully rearranges the video configuration around the disabled U2711 until I manually un-wedge things. If I shut down the PC while it’s still displaying the BIOS intro screen, then click-click the remote power switch, the U2711 will be good for another week or so.

Every month or so, the U2711 won’t light up after going into power-save mode, even though the PC is still running just fine. I set Lightlocker (which replaces the classic screensaver on Xubuntu) to blank the screen after 10 minutes and turn off the display power after 11 minutes. When the U2711 doesn’t light up, some delicate xrandr surgery through the U2713 will bring the U2711 back to life.

The starting situation looks like this:

xrandr
Screen 0: minimum 8 x 8, current 1440 x 2560, maximum 16384 x 16384
DP-0 disconnected primary (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected (normal left inverted right x axis y axis)
   2560x1440      60.0 +
   1920x1200      59.9  
   1920x1080      60.0     59.9     50.0     24.0     60.1     60.0     50.0  
   1680x1050      60.0  
   1600x1200      60.0  
   1280x1024      75.0     60.0  
   1280x800       59.8  
   1280x720       60.0     59.9     50.0  
   1152x864       75.0  
   1024x768       75.0     60.0  
   800x600        75.0     60.3  
   720x576        50.0     50.1  
   720x480        59.9     60.1  
   640x480        75.0     59.9     59.9  
DP-3 connected 1440x2560+0+0 left (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440      60.0*+
   1920x1200      59.9  
   1920x1080      60.0     59.9     50.0     24.0     60.1     60.0     50.0  
   1680x1050      60.0  
   1600x1200      60.0  
   1280x1024      75.0     60.0  
   1280x800       59.8  
   1280x720       60.0     59.9     50.0  
   1152x864       75.0  
   1024x768       75.0     60.0  
   800x600        75.0     60.3  
   720x576        50.0     50.1  
   720x480        59.9     60.1  
   640x480        75.0     59.9     59.9

Note that there’s no asterisk on DP-2’s 2650x1440 entry, which means it’s not active. In fact, it’s jammed in power-save mode and nothing other than a hard power cycle will wake it up.

The U2713 portrait monitor wakes up just fine, so X piles all the program windows into an untidy heap on that display, but, with enough Alt-Tab action, I can eventually resurface the console window and start typing:

xrandr --output DP-2 --off
xrandr --output DP-2 --auto
xrandr --output DP-3 --right-of DP-2

The DP-2 and DP-3 outputs correspond to what xrandr reported above.

Then I must rearrange all the windows on both monitors again, but that’s much easier than the hocus-pocus required to recover after rebooting the PC with the U2711 shut down.

The normal (or recovered) video situation looks like this:

xrandr
Screen 0: minimum 8 x 8, current 4000 x 2560, maximum 16384 x 16384
DP-0 disconnected primary (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440      60.0*+
   1920x1200      59.9  
   1920x1080      60.0     59.9     50.0     24.0     60.1     60.0     50.0  
   1680x1050      60.0  
   1600x1200      60.0  
   1280x1024      75.0     60.0  
   1280x800       59.8  
   1280x720       60.0     59.9     50.0  
   1152x864       75.0  
   1024x768       75.0     60.0  
   800x600        75.0     60.3  
   720x576        50.0     50.1  
   720x480        59.9     60.1  
   640x480        75.0     59.9     59.9  
DP-3 connected 1440x2560+2560+0 left (normal left inverted right x axis y axis) 597mm x 336mm
   2560x1440      60.0*+
   1920x1200      59.9  
   1920x1080      60.0     59.9     50.0     24.0     60.1     60.0     50.0  
   1680x1050      60.0  
   1600x1200      60.0  
   1280x1024      75.0     60.0  
   1280x800       59.8  
   1280x720       60.0     59.9     50.0  
   1152x864       75.0  
   1024x768       75.0     60.0  
   800x600        75.0     60.3  
   720x576        50.0     50.1  
   720x480        59.9     60.1  
   640x480        75.0     59.9     59.9

Note that DP-2 now sports an asterisk.

The width of Screen 0 covers the U2711 in landscape and the U2713 in portrait: 4000 = 2560+1440. The height comes from the U2713 in portrait mode: 2560.

That this should not be necessary goes without saying. The U2711 run with firmware revision A09, which was supposed to fix the problem, but Dell basically walked away from it.

I’m pretty much forced to use Displayport video for both monitors, as a low-profile nVidia card with two dual-link DVI-D outputs doesn’t seem to exist. The Dell Optiplex 980 disables the system board video when it finds a PCI-E video card, so there’s no way to run the U2713 from the system board Displayport and the U2711 from a dual-link DVI PCI-E video card.

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