Bug#689268: Intel HD 4000 (Ivy Bridge) graphics freeze

[Ingo <ingo.steiner@gmx.net>]

Interesting to see the differences between the 2 kernels. Compared to
my messages I found following lines in dmesg have disappeared with 3.5:

mtrr: type mismatch for e0000000,10000000 old: write-back new:
write-combining

[drm] MTRR allocation failed.  Graphics performance may suffer.
[drm:intel_dsm_platform_mux_info] *ERROR* MUX INFO call failed

i915 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
i915 0000:00:02.0: restoring config space at offset 0xf (was 0x100,
writing 0x10b)
i915 0000:00:02.0: restoring config space at offset 0x1 (was 0x900007,
writing 0x900407)
i915 0000:00:02.0: setting latency timer to 64

while enabling RC6 states has been added:

[drm] Enabling RC6 states: RC6 on, RC6p on, RC6pp off


Probably a hint to the root cause?

I also compared the BIOS settings:

Javier has these options/settings:
Integrated Graphics Share Memory   [64MB]
DVMT Memory                       [256MB]

I only have:
IGD DVMT Memory			[256MB]

(which I called previously "agp-aperture" - ancient name when PC's had
a dedicated AGP-Port). This is the setting which I did change from
"max" -> "256MB" and got my system stable - which still holds right now.

However the "mtrr" setups (/proc/mtrr) are still identical with both
kernels. Seems the "write-combining area" has become obsolete - or
still not implemented in i915?

Ingo