i915 and 1440p display w/ corrupt EDID

Mathias Burén
2014-09-24T17:08:26Z

Hi all,

I've a 1440p display with a non-sufficient/corrupt EDID. I'm running
3.17.0-997-lowlatency #201409192205 from
http://kernel.ubuntu.com/~kernel-ppa/mainline/drm-intel-next/ and this
intel driver on Ubuntu 12.04 LTS, on a Thinkpad T420:

"Module intel: vendor="X.Org Foundation"
[ 9.541] compiled for 1.14.5, module version = 2.99.904
SNA compiled: xserver-xorg-video-intel-lts-saucy
2:2.99.904-0ubuntu2.1~precise1 (Timo Aaltonen <tjaalton@ubuntu.com>)"

When I connect the display to the laptop via the docking station, the
laptop detects that there is a display connected, but there are no
modes available. I can add a mode like this:

xrandr --newmode "2560x1440_60.0" 311.83 2560 2744 3024 3488 1440 1441
1444 1490 -HSync +Vsync
xrandr --addmode HDMI3 2560x1440_60.0

But I get an error when trying to use it: "xrandr: Configure crtc 1 failed".

Does anyone have any tips on how to get the monitor working?

Regards
Mathias