xrandr weirdness: cannot find crtc

[Gilad Arnold]

Dear all,

This looks like a driver related issue, apologies if it isn't.

I'm running xf86-video-ati 6.12.2 on a Thinkpad T40. After startup the
X server is configuration looks as follows:

$ xrandr
Screen 0: minimum 320 x 200, current 1400 x 1050, maximum 1920 x 1200
VGA-0 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 546mm x 352mm
   1920x1200      60.0 +   60.0  
   1600x1200      75.0     70.0     65.0     60.0     60.0  
   1680x1050      60.0  
   1600x1000      60.0  
   1400x1050      74.8     60.0* 
   1280x1024      85.0     75.0     60.0  
   1280x960       85.0     60.0     60.0  
   1152x864       75.0  
   1024x768       85.0     75.1     75.0     70.1     60.0  
   832x624        74.6  
   800x600        85.1     72.2     75.0     60.3     56.2  
   640x480        85.0     75.0     72.8     75.0     60.0     59.9  
   720x400        85.0     70.1  
   640x400        85.1  
   640x350        85.1  
DVI-0 connected 1400x1050+0+0 (normal left inverted right x axis y axis) 546mm x 352mm
   1920x1200      60.0 +
   1600x1200      60.0     60.0  
   1680x1050      60.0  
   1600x1000      60.0  
   1400x1050      74.8     60.0* 
   1280x1024      85.0     75.0     60.0  
   1280x960       85.0     60.0     60.0  
   1152x864       75.0  
   1024x768       85.0     75.1     75.0     70.1     60.0  
   832x624        74.6  
   800x600        85.1     72.2     75.0     60.3     56.2  
   640x480        85.0     75.0     72.8     75.0     60.0     59.9  
   720x400        85.0     70.1  
   640x400        85.1  
   640x350        85.1  
LVDS connected 1400x1050+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1400x1050      50.0*+
   1280x1024      59.9     60.0  
   1280x960       60.0     59.9  
   1280x854       59.9  
   1280x800       59.8  
   1280x720       59.9  
   1152x768       59.8  
   1024x768       60.0     59.9  
   800x600        60.3     59.9     56.2  
   640x480        59.9     59.4  
S-video disconnected (normal left inverted right x axis y axis)


Running xrandr with --verbose reveals that VGA-0 and DVI-0 share crtc
1 (clones) while LVDS uses crtc 0. Now I try to change mode on DVI-0 but
the command fails with an error message:

$ xrandr --output DVI-0 --mode 1680x1050
xrandr: cannot find crtc for output DVI-0

Same happens with different modes (including --auto) and with VGA-0. To
work around the problem I have to turn off one of the two, then change
mode on the other (it has to be two separate commands, otherwise the
same error occurs):

$ xrandr --output VGA-0 --off
$ xrandr --output DVI-0 --mode 1680x1050

Any idea what's causing this? I recall this used to work with earlier
versions of the driver.

Thanks!

Gilad