[PATCH v2] drm/i915/display: Handle struct drm_plane_state.ignore_damage_clips

[Thomas Zimmermann <tzimmermann@suse.de>]

Calling drm_atomic_helper_check_plane_damage() in plane_atomic_check()
before copying the damage information guarantees that ignore_damage_clips
from struct drm_plane_state has the correct value. Although i915 does not
directly modify or use the flag, DRM's damage iterator will soon rely on
it.

Git commit 35ed38d58257 ("drm: Allow drivers to indicate the damage
helpers to ignore damage clips") introduced ignore_damage_clips to
selectively ignore damage clipping for certain framebuffer changes. The
mode-setting pipeline can disabled damage clippings for an atomic commit
by setting ignore_damage_clips in struct drm_plane_state. The atomic
commit will then do a full display update.

Future directions: there's currently a multitude of options that affect
damage clipping; with different places seeing different state. In order
to unify this, drm_atomic_helper_check_plane_state() will soon evaluate
all options in a single place and set ignore_damage_clips accordingly. All
later stages of the mode-setting pipeline will only look at this field.

v2:
- move _check_plane_damage() before reading damage first time (Sashiko)
- expand commit description

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
---
Taken with updates from the series at

  https://lore.kernel.org/dri-devel/20260610152505.260172-1-tzimmermann@suse.de/
---
 drivers/gpu/drm/i915/display/intel_plane.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_plane.c b/drivers/gpu/drm/i915/display/intel_plane.c
index a440f92ff00c..7d312c88a1db 100644
--- a/drivers/gpu/drm/i915/display/intel_plane.c
+++ b/drivers/gpu/drm/i915/display/intel_plane.c
@@ -873,6 +873,14 @@ static int plane_atomic_check(struct intel_atomic_state *state,
 		old_primary_crtc_plane_state = old_plane_state;
 	}
 
+	/*
+	 * Prepare plane-damage state before using it; do this on all
+	 * display versions to keep the underlying DRM plane state in
+	 * good shape.
+	 */
+	drm_atomic_helper_check_plane_damage(&new_plane_state->base,
+					     &new_uapi_plane_state->uapi);
+
 	intel_plane_copy_uapi_plane_damage(new_plane_state,
 					   old_primary_crtc_plane_state,
 					   new_primary_crtc_plane_state);

base-commit: fcaba3bc017906059b910ece3f83185e93010581
-- 
2.54.0