From mboxrd@z Thu Jan  1 00:00:00 1970
From: Heinz Diehl <htd+ml@fritha.org>
Subject: [Regression] 3.18 black screen after boot (bisected)
Date: Sun, 14 Dec 2014 12:58:31 +0100
Message-ID: <20141214115831.GA1634@fritha.org>
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To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-kernel@vger.kernel.org, airlied@linux.ie, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
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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@kiera linux-git]# git bisect bad
83f45fc360c8e16a330474860ebda872d1384c8c is the first bad commit
commit 83f45fc360c8e16a330474860ebda872d1384c8c
Author: Daniel Vetter <daniel.vetter@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.