[PATCH 00/10] drm/intel/display: Changes required to make vblank evasion PREEMPT_RT safe.

[Maarten Lankhorst <dev@lankhorst.se>]

CONFIG_PREEMPT_RT requires code to be as deterministic as possible,
and codes with interrupts disabled cannot use spinlocks.

In order to handle this correctly, we ensure any locking requirements
are handled before disabling interrupts, and only start locking again
after interrupts are re-enabled and timing sensitive path completed.

This also has the benefit of making the vblank evasion code more
deterministic; without locking there's much less jitter.

Previously, we scheduled vblank work on completion.
This is now handled by scheduling the vblank in advance, only arming
it upon completion without locks.

Maarten Lankhorst (9):
  drm/vblank_work: Add methods to schedule vblank_work in 2 stages
  drm/vblank: Add a 2-stage version of drm_crtc_arm_vblank_event
  drm/intel/display: Make intel_crtc_arm_vblank_event static
  drm/intel/display: Convert vblank event handling to 2-stage arming
  drm/i915/display: Move vblank put until after critical section
  drm/i915/display: Remove locking from intel_vblank_evade critical
    section
  drm/i915/display: Handle vlv dsi workaround in scanline_in_safe_range
    too
  drm/i915/display: Make get_vblank_counter use intel_de_read_fw()
  drm/i915/display: Do not take uncore lock in i915_get_vblank_counter

Mike Galbraith (1):
  drm/i915: Use preempt_disable/enable_rt() where recommended

 drivers/gpu/drm/drm_vblank.c                  |  64 +++++++++-
 drivers/gpu/drm/drm_vblank_work.c             | 110 +++++++++++++----
 drivers/gpu/drm/i915/display/intel_crtc.c     |  86 ++++++-------
 drivers/gpu/drm/i915/display/intel_crtc.h     |   1 -
 drivers/gpu/drm/i915/display/intel_cursor.c   |   8 +-
 drivers/gpu/drm/i915/display/intel_de.h       |   8 ++
 drivers/gpu/drm/i915/display/intel_vblank.c   | 115 ++++++++++--------
 drivers/gpu/drm/i915/display/intel_vblank.h   |   1 +
 drivers/gpu/drm/i915/intel_uncore.h           |  26 ++--
 .../drm/xe/compat-i915-headers/intel_uncore.h |   7 ++
 include/drm/drm_vblank.h                      |  14 ++-
 include/drm/drm_vblank_work.h                 |  12 ++
 12 files changed, 324 insertions(+), 128 deletions(-)

-- 
2.53.0