drm/i915: Revert async unpin and nonblocking atomic commit

drm/i915: Revert async unpin and nonblocking atomic commit

This reverts the following patches:

b94086eaf9ec56f1459be32d5b1d0c11024d3601 drm/i915: Allow nonblocking update of pageflips.
b9a723c5d58c82e5b1f7a2ce6280656d2da1c174 drm/i915: Check for unpin correctness.
7cdff61a405e061a51e375872217df19f5bf5a34 Reapply "drm/i915: Avoid stalling on pending flips for legacy cursor updates"
d38ba3a5be488f234ed49da6d1d5901f1dfbe889 drm/i915: Make unpin async.
0b7e93ab9644b8d166b8b2e6f6238dc395d64560 drm/i915: Prepare connectors for nonblocking checks.
30b4d0304cdd058eeedf736df4b87c4bebe00660 drm/i915: Pass atomic states to fbc update functions.
b581e619a49421c16f446fe297e92a6ce1729964 drm/i915: Remove reset_counter from intel_crtc.
de5ef10d9416b12ad70f288b1611a5fb4ea6eda6 drm/i915: Remove queue_flip pointer.
9a6c24d127a10d31718f2df4e1188596c520b138 drm/i915: Remove use_mmio_flip kernel parameter.
be743331f68a645972473d2624f98d7b68f8cce0 drm/i915: Remove cs based page flip support.
452b79e932b0bb9c46c95bb624f88d7be6f1bb75 drm/i915: Rework intel_crtc_page_flip to be almost atomic, v3.
1e7106f7cd7a9b7dba260f9decd84ce8e716ddb6 drm/i915: Add the exclusive fence to plane_state.
39c241d91785de8511b3be154521cd90b730862d drm/i915: Convert flip_work to a list.
3ae29ff192f2ee774bc0dd1476d1c52e51562807 drm/i915: Allow mmio updates on all platforms, v2.
bdae77f4aa642da4eecced38150c4994dcea1e95 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>