Bug#692225: [3.2->3.6.4 regression] screen starts to flicker after suspend-to-disk

[Jonathan Nieder <jrnieder@gmail.com>]

# [1]
forwarded 692225 https://bugs.freedesktop.org/56118
quit

Sebastian Ramacher wrote:

> I've recently upgrade from 3.2 to 3.6. Since the upgrade after resuming from
> supsend-to-disk the screen starts to flicker and the kernel log contains the
> following traceback:
>
> [ 4730.108047] ------------[ cut here ]------------
> [ 4730.108073] WARNING: at /build/buildd-linux_3.6.4-1~experimental.1-amd64-QnAy6j/linux-3.6.4/drivers/gpu/drm/i915/intel_display.c:1225 intel_crtc_disable+0x52/0x86 [i915]()
> [ 4730.108074] Hardware name: 7458WTH
> [ 4730.108076] pipe B assertion failure (expected off, current on)

Oh, here's a better link: [1].  This is said to be fixed by

  fa55583797d1 drm/i915: fixup the plane->pipe fixup code

A naive backport of that depends on

  24929352481f drm/i915: read out the modeset hw state at load and
               resume time

which in turn depends on the series

  *: implement get_hw_state
  *: convert to encoder->disable/enable

Jonathan