Bug#645983: 2560x1440 60Hz not working (Dell U2711)
I connect a Dell U2711 to the docking station using the display port
interface (DP2 in xrandr, see below) and a diplayport cable. Then, the
maximum resolution of 2560x1440 at 60.0 Hz does not work, the screen
is black. The lower resolutions (e.g. 1920x1200) work.
As suggested in http://rndhero.org/cms/index.php?id=10 a workaround
consists of manually setting the refresh rate to 35 Hz.
[ 52045.402] (II) intel(0): Integrated Graphics Chipset: Intel(R) GM45
[ 52045.402] (--) intel(0): Chipset: "GM45"
DP2 connected 2560x1440+0+0 (normal left inverted right x axis y axis)
597mm x 336mm
2560x1440 60.0 +
1280x1024 75.0 60.0
1024x768 75.1 60.0
800x600 75.0 60.3
640x480 75.0 60.0