[PATCH/RFC] i915: fix screen flickering

[Jan Niehusmann]

On Wed, Apr 29, 2015 at 12:23:43AM +0200, Thomas Gummerer wrote:
> I forgot to mention, the bug only occurs after suspending the system and
> waking it up again.  In that case, moving the mouse pointer around on
> the build in laptop screen triggers the flickering, while the external
> monitor works just fine.

My Lenovo X201s shows the same symptoms with v4.1.0-rc1, and your patch
seems to help.

Another detail: The flickering only happens when both outputs are
active, using xrandr to disable one output makes the other one working
fine, again.

> Might be unrelated, but I only managed to trigger the bug when the
> system is suspended after the synergy server has started.

I don't have synergy installed, so this can't be a strict requirement
for triggering the bug.

Jan