[Intel-gfx] [Regression] 3.18 black screen after boot (bisected)

[Heinz Diehl]

Hi,

since kernel 3.18 I'm no longer able to run X on my machine. While
3.17.6 is fine, 3.18 leaves me with a black screen when starting
X. Booting into runlevel 1/3 is fine.

I did a "git bisect", and the offending commit is this one:

[root at kiera linux-git]# git bisect bad
83f45fc360c8e16a330474860ebda872d1384c8c is the first bad commit
commit 83f45fc360c8e16a330474860ebda872d1384c8c
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Wed Aug 6 09:10:18 2014 +0200

    drm: Don't grab an fb reference for the idr

[....]

I double-checked, and 3.18 is fine with this commit reverted.

My machine is an Asus U45JC laptop, and the CPU is an Intel i450M
(Ironlake). Please contact me if I can help in any way (I'm subscribed
to lkml, but not to other X or kernel related lists).

Thanks,
 Heinz.