ubuntu-x-swat team mailing list archive

[Ketil Malde <ketil@xxxxxxxxx>]

Public bug reported:

In most cases, 'xrandr --auto' does the Right Thing configuring the
avilable displays.  However, after I have used the VGA output of my
laptop and return to use the HDMI output from my docking station, I get
this message:

    % xrandr --auto
    xrandr: cannot find crtc for output HDMI3

The setup look like this:

    % xrandr
    Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
    LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 277mm x 156mm
       1366x768       59.6*+
       1360x768       59.8     60.0
       1024x768       60.0
       800x600        60.3     56.2
       640x480        59.9
    VGA1 disconnected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
    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 connected (normal left inverted right x axis y axis)
       1680x1050      59.9 +
       1280x1024      75.0     60.0
       1152x864       75.0
       1024x768       75.1     60.0
       800x600        75.0     60.3
       640x480        75.0     60.0
       720x400        70.1
    DP2 disconnected (normal left inverted right x axis y axis)
    DP3 disconnected (normal left inverted right x axis y axis)

Note that VGA1 is disconnected, but configured with 1024x768.
Deconfiguring it works:

    % xrandr --output VGA1 --off
    % xrandr --auto

This isn't entirely obvious to figure out, and I think --auto should do
this (i.e. turn off unused displays to free a crtc) automatically.  If
this is unacceptable for some reason, I suggest the error message should
be changed to be more informative, e.g. something like:

    % xrandr --auto
    xrandr: cannot find crtc for output HDMI3.  VGA1 is currently configured but disconnected, to free its crtc, use 'xrandr --output VGA1 --off'.  To share a crtc, configure HDMI3 with the same mode as a configured display.

(This is on a Lenovo X220, with Oneiric, but I believe many systems have
fewer crtcs than display connections)

** Affects: x11-xserver-utils (Ubuntu)
     Importance: Undecided
         Status: New

** Description changed:

+ In most cases, 'xrandr --auto' does the Right Thing configuring the
+ avilable displays.  However, after I have used the VGA output of my
+ laptop and return to use the HDMI output from my docking station, I get
+ this message:
  
- In most cases, 'xrandr --auto' does the Right Thing configuring the avilable displays.  However, after I have used the VGA output of my laptop and return to use the HDMI output from my docking station, I get this message:
- 
-     % xrandr --auto
-     xrandr: cannot find crtc for output HDMI3
+     % xrandr --auto
+     xrandr: cannot find crtc for output HDMI3
  
  The setup look like this:
  
-     % xrandr   
-     Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
-     LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 277mm x 156mm
-        1366x768       59.6*+
-        1360x768       59.8     60.0  
-        1024x768       60.0  
-        800x600        60.3     56.2  
-        640x480        59.9  
-     VGA1 disconnected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
-     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 connected (normal left inverted right x axis y axis)
-        1680x1050      59.9 +
-        1280x1024      75.0     60.0  
-        1152x864       75.0  
-        1024x768       75.1     60.0  
-        800x600        75.0     60.3  
-        640x480        75.0     60.0  
-        720x400        70.1  
-     DP2 disconnected (normal left inverted right x axis y axis)
-     DP3 disconnected (normal left inverted right x axis y axis)
+     % xrandr
+     Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
+     LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 277mm x 156mm
+        1366x768       59.6*+
+        1360x768       59.8     60.0
+        1024x768       60.0
+        800x600        60.3     56.2
+        640x480        59.9
+     VGA1 disconnected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
+     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 connected (normal left inverted right x axis y axis)
+        1680x1050      59.9 +
+        1280x1024      75.0     60.0
+        1152x864       75.0
+        1024x768       75.1     60.0
+        800x600        75.0     60.3
+        640x480        75.0     60.0
+        720x400        70.1
+     DP2 disconnected (normal left inverted right x axis y axis)
+     DP3 disconnected (normal left inverted right x axis y axis)
  
  Note that VGA1 is disconnected, but configured with 1024x768.
  Deconfiguring it works:
  
-     % xrandr --output VGA1 --off
-     % xrandr --auto
+     % xrandr --output VGA1 --off
+     % xrandr --auto
  
  This isn't entirely obvious to figure out, and I think --auto should do
  this (i.e. turn off unused displays to free a crtc) automatically.  If
  this is unacceptable for some reason, I suggest the error message should
  be changed to be more informative, e.g. something like:
  
-     % xrandr --auto
-     xrandr: cannot find crtc for output HDMI3.  VGA1 is currently configured but disconnected, to free its crtc, use 'xrandr --output VGA1 --off'.  To share a crtc, configure HDMI3 with the same mode as a configured display.
+     % xrandr --auto
+     xrandr: cannot find crtc for output HDMI3.  VGA1 is currently configured but disconnected, to free its crtc, use 'xrandr --output VGA1 --off'.  To share a crtc, configure HDMI3 with the same mode as a configured display.
  
- (This is on a Lenovo X220, but I believe many systems have fewer crtcs
- than display connections)
+ (This is on a Lenovo X220, with Oneiric, but I believe many systems have
+ fewer crtcs than display connections)

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https://bugs.launchpad.net/bugs/907679

Title:
  xrandr --auto should turn off disconnected displays to free crtcs

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