4.4-rc, intel dri i915, regular hangs and corruptions

[Norbert Preining <preining@logic.at>]

Dear all,

since 4.4-rc (at least rc2 it was the first I tested), the Intel DRI
is in very broken state. 

Hardware: Sony VAIO Pro
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
	Subsystem: Sony Corporation Device 90b6
	Flags: bus master, fast devsel, latency 0, IRQ 40
	Memory at f5c00000 (64-bit, non-prefetchable) [size=4M]
	Memory at e0000000 (64-bit, prefetchable) [size=256M]
	I/O ports at f000 [size=64]
	Expansion ROM at <unassigned> [disabled]
	Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
	Capabilities: [d0] Power Management version 2
	Capabilities: [a4] PCI Advanced Features
	Kernel driver in use: i915

Symptoms:

* font corruption
  sometime sets of glyphs, or practically all glyphs disappear
  related probably to bug 
  https://bugs.freedesktop.org/show_bug.cgi?id=55500
  I have sent some info there already, without response

  Currently my font displays some kind of strange symbols instead of
  an m ... looks a bit like a Kanji.

* drm/i915 hang:
  GPU HANG: ecode 7:0:0x86d2bff9, in cinnamon [9300], reason: Ring hung, action: reset
  opened a new bug as advised
  https://bugs.freedesktop.org/show_bug.cgi?id=93279
  several other hangs like that, reported only one

* intelfb is dead
  switching to the console often leaves a black console

Most of the time this happens after a suspend to ram and wake up, but
not always.

Let me know if there is anything else one might want to know

Thanks

Norbert

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PREINING, Norbert                               http://www.preining.info
JAIST, Japan                                 TeX Live & Debian Developer
GPG: 0x860CDC13   fp: F7D8 A928 26E3 16A1 9FA0  ACF0 6CAC A448 860C DC13
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