drm: Add helper iterator functions for plane fb_damage_clips blob

With fb_damage_clips blob property in drm_plane_state, this patch adds
helper iterator to traverse the damage clips that lie inside plane src.
Iterator will return full plane src as damage in case need full plane
update or damage is not specified.

v2:
- Plane src clipping correction
- Handle no plane update case in iter_next

Signed-off-by: Deepak Rawat <drawat@vmware.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

2 files changed, 57 insertions, 1 deletions

diff --git a/include/drm/drm_damage_helper.h b/include/drm/drm_damage_helper.h
index 59584cbf3d40..b9a0d05fb093 100644
--- a/include/drm/drm_damage_helper.h
+++ b/include/drm/drm_damage_helper.h
@@ -34,8 +34,62 @@
 
 #include <drm/drm_atomic_helper.h>
 
+/**
+ * drm_atomic_for_each_plane_damage - Iterator macro for plane damage.
+ * @iter: The iterator to advance.
+ * @rect: Return a rectangle in fb coordinate clipped to plane src.
+ *
+ * Note that if the first call to iterator macro return false then no need to do
+ * plane update. Iterator will return full plane src when damage is not passed
+ * by user-space.
+ */
+#define drm_atomic_for_each_plane_damage(iter, rect) \
+	while (drm_atomic_helper_damage_iter_next(iter, rect))
+
+/**
+ * struct drm_atomic_helper_damage_iter - Closure structure for damage iterator.
+ *
+ * This structure tracks state needed to walk the list of plane damage clips.
+ */
+struct drm_atomic_helper_damage_iter {
+	/* private: Plane src in whole number. */
+	struct drm_rect plane_src;
+	/* private: Rectangles in plane damage blob. */
+	const struct drm_rect *clips;
+	/* private: Number of rectangles in plane damage blob. */
+	uint32_t num_clips;
+	/* private: Current clip iterator is advancing on. */
+	uint32_t curr_clip;
+	/* private: Whether need full plane update. */
+	bool full_update;
+};
+
 void drm_plane_enable_fb_damage_clips(struct drm_plane *plane);
 void drm_atomic_helper_check_plane_damage(struct drm_atomic_state *state,
 					  struct drm_plane_state *plane_state);
+void
+drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
+				   const struct drm_plane_state *old_state,
+				   const struct drm_plane_state *new_state);
+bool
+drm_atomic_helper_damage_iter_next(struct drm_atomic_helper_damage_iter *iter,
+				   struct drm_rect *rect);
+
+/**
+ * drm_helper_get_plane_damage_clips - Returns damage clips in &drm_rect.
+ * @state: Plane state.
+ *
+ * Returns plane damage rectangles in internal &drm_rect. Currently &drm_rect
+ * can be obtained by simply typecasting &drm_mode_rect. This is because both
+ * are signed 32 and during drm_atomic_check_only() it is verified that damage
+ * clips are inside fb.
+ *
+ * Return: Clips in plane fb_damage_clips blob property.
+ */
+static inline struct drm_rect *
+drm_helper_get_plane_damage_clips(const struct drm_plane_state *state)
+{
+	return (struct drm_rect *)drm_plane_get_damage_clips(state);
+}
 
 #endif
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 87153ecb5f1f..6078c700d9ba 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -830,7 +830,9 @@ drm_plane_get_damage_clips_count(const struct drm_plane_state *state)
  * drm_plane_get_damage_clips - Returns damage clips.
  * @state: Plane state.
  *
- * Note that this function returns uapi type &drm_mode_rect.
+ * Note that this function returns uapi type &drm_mode_rect. Drivers might
+ * instead be interested in internal &drm_rect which can be obtained by calling
+ * drm_helper_get_plane_damage_clips().
  *
  * Return: Damage clips in plane fb_damage_clips blob property.
  */