drm/i915: Implement workaround for broken CS tlb on i830/845

Now that Chris Wilson demonstrated that the key for stability on early
gen 2 is to simple _never_ exchange the physical backi

drm/i915: Implement workaround for broken CS tlb on i830/845

Now that Chris Wilson demonstrated that the key for stability on early
gen 2 is to simple _never_ exchange the physical backing storage of
batch buffers I've tried a stab at a kernel solution. Doesn't look too
nefarious imho, now that I don't try to be too clever for my own good
any more.

v2: After discussing the various techniques, we've decided to always blit
batches on the suspect devices, but allow userspace to opt out of the
kernel workaround assume full responsibility for providing coherent
batches. The principal reason is that avoiding the blit does improve
performance in a few key microbenchmarks and also in cairo-trace
replays.

Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet:
- Drop the hunk which uses HAS_BROKEN_CS_TLB to implement the ring
wrap w/a. Suggested by Chris Wilson.
- Also add the ACTHD check from Chris Wilson for the error state
dumping, so that we still catch batches when userspace opts out of
the w/a.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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Merge tag 'v3.7-rc2' into drm-intel-next-queued

Linux 3.7-rc2

Backmerge to solve two ugly conflicts:
- uapi. We've already added new ioctl definitions for -next. Do I need to sa

Merge tag 'v3.7-rc2' into drm-intel-next-queued

Linux 3.7-rc2

Backmerge to solve two ugly conflicts:
- uapi. We've already added new ioctl definitions for -next. Do I need to say more?
- wc support gtt ptes. We've had to revert this for snb+ for 3.7 and
also fix a few other things in the code. Now we know how to make it
work on snb+, but to avoid losing the other fixes do the backmerge
first before re-enabling wc gtt ptes on snb+.

And a few other minor things, among them git getting confused in
intel_dp.c and seemingly causing a conflict out of nothing ...

Conflicts:
drivers/gpu/drm/i915/i915_reg.h
drivers/gpu/drm/i915/intel_display.c
drivers/gpu/drm/i915/intel_dp.c
drivers/gpu/drm/i915/intel_modes.c
include/drm/i915_drm.h

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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UAPI: (Scripted) Disintegrate include/drm

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>

UAPI: (Scripted) Disintegrate include/drm

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>

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