drm/i915: Revert async unpin and nonblocking atomic commit

drm/i915: Revert async unpin and nonblocking atomic commit

This reverts the following patches:

d55dbd06bb5e1399aba9ab5227465339d1bbefff drm/i915: Allow nonblocking update of pageflips.
15c86bdb760185e871c7a0f559978328aa500971 drm/i915: Check for unpin correctness.
95c2ccdc82d520f59ae3b6fdc097b63c9b7082bb Reapply "drm/i915: Avoid stalling on pending flips for legacy cursor updates"
a6747b7304a9d66758a196d885dab8bbfa5e7d1f drm/i915: Make unpin async.
03f476e1fcb42fca88fc50b94b0d3adbdbe887f0 drm/i915: Prepare connectors for nonblocking checks.
2099deffef4404f949ba1b68d2b17e0608190bc2 drm/i915: Pass atomic states to fbc update functions.
ee7171af72c39c18b7d7571419a4ac6ca30aea66 drm/i915: Remove reset_counter from intel_crtc.
2ee004f7c59b2e642f0bb2834f847d756f2dd7b7 drm/i915: Remove queue_flip pointer.
b8d2afae557dbb9b9c7bc6f6ec4f5278f3c4c34e drm/i915: Remove use_mmio_flip kernel parameter.
8dd634d922615ec3a9af7976029110ec037f8b50 drm/i915: Remove cs based page flip support.
143f73b3bf48c089b40f58462dd7f7c199fd4f0f drm/i915: Rework intel_crtc_page_flip to be almost atomic, v3.
84fc494b64e8c591be446a966b7447a9db519c88 drm/i915: Add the exclusive fence to plane_state.
6885843ae164e11f6c802209d06921e678a3f3f3 drm/i915: Convert flip_work to a list.
aa420ddd8eeaa5df579894a412289e4d07c2fee9 drm/i915: Allow mmio updates on all platforms, v2.
afee4d8707ab1f21b7668de995be3a5961e83582 Revert "drm/i915: Avoid stalling on pending flips for legacy cursor updates"

"drm/i915: Allow nonblocking update of pageflips" should have been
split up, misses a proper commit message and seems to cause issues in
the legacy page_flip path as demonstrated by kms_flip.

"drm/i915: Make unpin async" doesn't handle the unthrottled cursor
updates correctly, leading to an apparent pin count leak. This is
caught by the WARN_ON in i915_gem_object_do_pin which screams if we
have more than DRM_I915_GEM_OBJECT_MAX_PIN_COUNT pins.

Unfortuantely we can't just revert these two because this patch series
came with a built-in bisect breakage in the form of temporarily
removing the unthrottled cursor update hack for legacy cursor ioctl.
Therefore there's no other option than to revert the entire pile :(

There's one tiny conflict in intel_drv.h due to other patches, nothing
serious.

Normally I'd wait a bit longer with doing a maintainer revert, but
since the minimal set of patches we need to revert (due to the bisect
breakage) is so big, time is running out fast. And very soon
(especially after a few attempts at fixing issues) it'll be really
hard to revert things cleanly.

Lessons learned:
- Not a good idea to rush the review (done by someone fairly new to
  the area) and not make sure domain experts had a chance to read it.

- Patches should be properly split up. I only looked at the two
  patches that should be reverted in detail, but both look like the
  mix up different things in one patch.

- Patches really should have proper commit messages. Especially when
  doing more than one thing, and especially when touching critical and
  tricky core code.

- Building a patch series and r-b stamping it when it has a built-in
  bisect breakage is not a good idea.

- I also think we need to stop building up technical debt by
  postponing atomic igt testcases even longer. I think it's clear that
  there's enough corner cases in this beast that we really need to
  have the testcases _before_ the next step lands.

(cherry picked from commit 5a21b6650a239ebc020912968a44047701104159
from drm-intel-next-queeud)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>