Created attachment 73239 [details]
dmesg_all

System Environment:
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Arch:       x86_64
Platform:   Haswell
Kernel:     (drm-intel-fixes) 0f3b6849dd55943d915f4b461d7db5e8308d4083

Bug detailed description:
-------------------------
It happens on haswell with -fixes kernel. It also happens on -queued kernel.
I can't catch a good commit.

dmesg:
<6>[    3.963129] [drm] Initialized drm 1.1.0 20060810
<6>[    3.966972] [drm] Memory usable by graphics device = 2048M
<6>[    3.966976] fb: conflicting fb hw usage inteldrmfb vs VESA VGA - removing generic driver
<3>[    3.982474] [drm:i915_write32] *ERROR* Unknown unclaimed register before writing to c5100
<6>[    3.982510] [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
<6>[    3.982511] [drm] Driver supports precise vblank timestamp query.
<6>[    4.233857] [drm] GMBUS [i915 gmbus dpd] timed out, falling back to bit banging on pin 6
<6>[    4.260260] fbcon: inteldrmfb (fb0) is primary device
<6>[    4.469661] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
<6>[    4.478856] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0
<6>[    5.710454] [drm] Enabling RC6 states: RC6 on, RC6p off, RC6pp off


Reproduce steps:
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1. dmesg -r | egrep "<[1-6]>" |grep drm