[Intel-gfx] Trouble with dell latitude E6420

[Giacomo Comes]

I have a dell latitude E6420 with Sandybridge Mobile (GT2).
Since I got it (about one year ago), it has been a nightmare to run linux on it.
At the beginning I installed openSUSE 11.4 (kernel 2.6.37.6) and the laptop
would freeze almost immediately. After that I waited for newer kernels in order to
see if things would improve. They did improve indeed and finally with kernel 3.0
I was able to run linux (openSUSE 11.4) without laptop freeze or screen issue.
Unfortunately, the only kernel that works with my laptop is 3.0. Newer kernel
(3.1, 3.2, 3.3 and 3.4) do not work.
This is what happen if I run kernel 2.6.39, 3.1, 3.2, 3.3 and 3.4:
The laptop boot and does the boot process fine. At the end of the boot process X
starts and here the problem appears (about 50% of the times):
the screen goes black on the left side (about 2/3 of the whole screen) with white
stripes to the right side (the remaining 1/3).
The laptop is not dead: I can remotely login or I can perform a clean shutdown
if I press the power button, but the screen is totally dead.
Another strange issue is that after a bad boot (with the black screen) at the
next reboot the screen will start to flicker. The flickering will last some time
and it will become less intense as the time goes until it will disappear completely.
The funny thing is that the intensity of flicker depends on how long I keep the
black screen. If, after the boot process, the black screen appears and I reboot
the laptop immediately, then the flicked is moderate and it disappear after
1 or 2 minutes. If I keep the black screen for 1 minute or more, then after the
reboot the flicker is very intense and it takes much more to fade.

Right now I run openSUSE 12.1 on the laptop, but I had to perform the following
trick: because openSUSE 12.1 ships with kernel 3.1, in order to make openSUSE run on my
laptop I have the options:
1) downgrade to kernel 3.0 (I use 3.0.7)
2) recompile the openSUSE kernel 3.1 replacing the directory drivers/gpu/drm/i915
with the content of the same directory from kernel 3.0 source tree.

I choose the second option as I can run the latest openSUSE kernel with patches
and fixes.

I have searched google to see if other users have my same problem and
I have found few references to a problem similar to mine:

http://lists.freedesktop.org/archives/intel-gfx/2011-March/009822.html
http://www.gossamer-threads.com/lists/linux/kernel/1474140
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/794474

But in none there is a mention on how to fix the problem.

Is there any chance to improve the intel kernel driver to make it work
for my laptop as it was in kernel 3.0?

I can provide any information/testing as needed.

Giacomo