How do I resolve "xrandr: cannot find crtc for output"?

Question

Whenever I come to work I type

xrandr --auto
xrandr --output VGA1 --right-of LVDS1

This gets my second display working, however now I get

xrandr: cannot find crtc for output VGA1

For reference here is the output of xrandr,

Screen 0: minimum 320 x 200, current 3286 x 1080, maximum 8192 x 8192
LVDS1 connected 1366x768+1920+0 (normal left inverted right x axis y axis) 277mm x 156mm
   1366x768       60.0*+
   1360x768       59.8     60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 connected (normal left inverted right x axis y axis)
   1680x1050      59.9 +
   1600x1200      60.0  
   1680x945       60.0  
   1400x1050      74.9     60.0  
   1600x900       60.0  
   1280x1024      75.0     60.0  
   1440x900       75.0     59.9  
   1280x960       60.0  
   1366x768       60.0  
   1360x768       60.0  
   1280x800       74.9     59.8  
   1152x864       75.0  
   1280x768       74.9     59.9  
   1280x720       60.0  
   1024x768       75.1     70.1     60.0  
   1024x576       60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   848x480        60.0  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
DP2 disconnected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
DP3 disconnected (normal left inverted right x axis y axis)
  1920x1080 (0x1df)  148.5MHz
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock   67.5KHz
        v: height 1080 start 1084 end 1089 total 1125           clock   60.0Hz

Answer 1

This occurs becaues you have another screen already active, in this case DP2. DP2 here is a monitor running off of a DisplayPort. The laptop is a Lenovo x230 and it was booted with an Ultrabase 3 docking station.

You can resolve this issue by simply turning off the screen using,

xrandr --output DP2 --off

Now, in XFCE or similar workstation you should see your desktop area shrink. Then you can continue running your xrandr commands as you normally would,

xrandr --auto
xrandr ...

Answer 2

So does that mean that you can only have two screens active at the same time? Do you have to set one external screen to --off before turning another one on?

I've been battling a bit with my own setup (Dell Latitude, docking station, an external VGA screen and another external HDMI screen): so far, no luck.

This command works as expected:

xrandr --output HDMI-3 --auto --left-of LVDS-1 --output LVDS-1 --auto --primary --output VGA-1 --off

That command also works as expected:

xrandr --output HDMI-3 --off --left-of LVDS-1 --output LVDS-1 --auto --primary --output VGA-1 --auto --right-of LVDS-1 

But the following combination (what I'd whish) doesn't work:

xrandr --output HDMI-3 --auto --left-of LVDS-1 --output LVDS-1 --auto --primary --output VGA-1 --auto --right-of LVDS-1 
xrandr: cannot find crtc for output VGA-1

Answer 3

I know this is an old post, but my problem ended up being the cable. It wasn't fast enough to support the resolution I was setting. A better cable fixed it, or a lower resolution.