xrandr weirdness: cannot find crtc
Submitted by Gilad Arnold
Assigned to Keith Packard @keithp
Description
I'm running xf86-video-ati 6.12.2 on a Thinkpad T40/42. After startup, x11 is configured 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. The two monitors (in fact, two inputs of the same monitor) have the exact same modelines, including refresh rate (verified with verbose output).
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
Posting to the xf86-video-ati mailing list, it is believed that this is a problem with xrandr incorrectly trying to set the modes. Thanks for your help!
Version: 7.4 (2008.09)