Comment 23 for bug 160871

Revision history for this message
In , Bryce Harrington (bryce) wrote :

Several Ubuntu users are reporting this issue:

https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-ati/+bug/160871

With an ATI 7500, the lcd screen shows 1400x1050, but xrandr offers no other resolutions, although several are supported.

http://launchpadlibrarian.net/12221450/xorg.conf
http://launchpadlibrarian.net/12221452/Xorg.0.log

(II) RADEON(0): Printing DDC gathered Modelines:
(II) RADEON(0): Modeline "1400x1050"x0.0 108.00 1400 1448 1560 1688 1050 1051 1054 1068 -hsync -vsync (64.0 kHz)
(II) RADEON(0): DDC Type: 4, Detected Monitor Type: 2
(II) RADEON(0): EDID data from the display on connector: Proprietary/LVDS ----------------------
(II) RADEON(0): Manufacturer: HTC Model: 17b0 Serial#: 420189172
...
(II) RADEON(0): First detailed timing not preferred mode in violation of standard!(II) RADEON(0): redX: 0.590 redY: 0.340 greenX: 0.320 greenY: 0.560

Looks like it's using DDC instead of EDID, and DDC is only returning the one resolution.

Adding Option "NoDDC" to xorg.conf fixes the issue.