drm/i915: Split update_plane() into update_noarm() + update_arm()

The amount of plane registers we have to write has been steadily
increasing, putting more pressure on the vblank evasion mechanism
and forcing us to increase its time budget. Let's try to take some
of the pressure off by splitting plane updates into two parts:
1) write all non-self arming plane registers, ie. the registers
   where the write actually does nothing until a separate arming
   register is also written which will cause the hardware to latch
   the new register values at the next start of vblank
2) write all self arming plane registers, ie. registers which always
   just latch at the next start of vblank, and registers which also
   arm other registers to do so

Here we just provide the mechanism, but don't actually implement
the split on any platform yet. so everything stays now in the _arm()
hooks. Subsequently we can move a whole bunch of stuff into the
_noarm() part, especially in more modern platforms where the number
of registers we have to write is also the greatest. On older
platforms this is less beneficial probably, but no real reason
to deviate from a common behaviour.

And let's sprinkle some TODOs around the areas that will need
adapting.

Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018115030.3547-5-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.h b/drivers/gpu/drm/i915/display/intel_atomic_plane.h
index 62e5a2a77fd4..7907f601598e 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic_plane.h
+++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.h
@@ -30,20 +30,25 @@ void intel_plane_copy_uapi_to_hw_state(struct intel_plane_state *plane_state,
 				       struct intel_crtc *crtc);
 void intel_plane_copy_hw_state(struct intel_plane_state *plane_state,
 			       const struct intel_plane_state *from_plane_state);
-void intel_update_plane(struct intel_plane *plane,
-			const struct intel_crtc_state *crtc_state,
-			const struct intel_plane_state *plane_state);
-void intel_disable_plane(struct intel_plane *plane,
-			 const struct intel_crtc_state *crtc_state);
+void intel_plane_update_noarm(struct intel_plane *plane,
+			      const struct intel_crtc_state *crtc_state,
+			      const struct intel_plane_state *plane_state);
+void intel_plane_update_arm(struct intel_plane *plane,
+			    const struct intel_crtc_state *crtc_state,
+			    const struct intel_plane_state *plane_state);
+void intel_plane_disable_arm(struct intel_plane *plane,
+			     const struct intel_crtc_state *crtc_state);
 struct intel_plane *intel_plane_alloc(void);
 void intel_plane_free(struct intel_plane *plane);
 struct drm_plane_state *intel_plane_duplicate_state(struct drm_plane *plane);
 void intel_plane_destroy_state(struct drm_plane *plane,
 			       struct drm_plane_state *state);
-void skl_update_planes_on_crtc(struct intel_atomic_state *state,
-			       struct intel_crtc *crtc);
-void i9xx_update_planes_on_crtc(struct intel_atomic_state *state,
-				struct intel_crtc *crtc);
+void intel_update_planes_on_crtc(struct intel_atomic_state *state,
+				 struct intel_crtc *crtc);
+void skl_arm_planes_on_crtc(struct intel_atomic_state *state,
+			    struct intel_crtc *crtc);
+void i9xx_arm_planes_on_crtc(struct intel_atomic_state *state,
+			     struct intel_crtc *crtc);
 int intel_plane_atomic_check_with_state(const struct intel_crtc_state *old_crtc_state,
 					struct intel_crtc_state *crtc_state,
 					const struct intel_plane_state *old_plane_state,