[Intel-gfx] drm-intel-fixes queue

[Chris Wilson]

A few changes since the first posting. I've dropped the two controversial
pipe/plane enabling patches and we wait QA testing to confirm that the
remaining patches are indeed sufficient to fix the bug. New to this
posting are a few more bug fixes and the pipelined fence fix. The latter
does need testing whilst it is behaving itself on my gen3 boxes, the
manifestation of associated bugs is highly timing dependent and so maybe
on another machine they will attack in droves. Whilst the pipelined fence
fixes are not critical for stability, I did introduce a stall between
concurrent fenced batches to fix the tiling corruption which will have
regressed performance.

I've decided not to include Ben's rc6 Ironlake fixes, but to queue those
for -next. 3 more months of testing will do no harm for a feature that
has been nothing but 15 months of misery.

Thanks for the comments so far everybody, now lets have some more!
-Chris