[RFC 2/3] drm: Add helper iterator functions to iterate over plane damage.

[Deepak Rawat <drawat@vmware.com>]

With damage property in drm_plane_state, this patch adds helper iterator
to traverse the damage clips. Iterator will return the damage rectangles
in framebuffer, plane or crtc coordinates as need by driver
implementation.

Signed-off-by: Deepak Rawat <drawat@vmware.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 122 ++++++++++++++++++++++++++++++++++++
 include/drm/drm_atomic_helper.h     |  39 ++++++++++++
 2 files changed, 161 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 55b44e3..355b514 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3865,3 +3865,125 @@ void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj
 	memcpy(state, obj->state, sizeof(*state));
 }
 EXPORT_SYMBOL(__drm_atomic_helper_private_obj_duplicate_state);
+
+/**
+ * drm_atomic_helper_damage_iter_init - initialize the damage iterator
+ * @iter: The iterator to initialize.
+ * @type: Coordinate type caller is interested in.
+ * @state: plane_state from which to iterate the damage clips.
+ * @hdisplay: Width of crtc on which plane is scanned out.
+ * @vdisplay: Height of crtc on which plane is scanned out.
+ *
+ * Initialize an iterator that is used to translate and clip a set of damage
+ * rectangles in framebuffer coordinates to plane and crtc coordinates. The type
+ * argument specify which type of coordinate to iterate in.
+ *
+ * Returns: 0 on success and negative error code on error. If an error code is
+ * returned then it means the plane state should not update.
+ */
+int
+drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
+				   enum drm_atomic_helper_damage_clip_type type,
+				   const struct drm_plane_state *state,
+				   uint32_t hdisplay, uint32_t vdisplay)
+{
+	if (!state || !state->crtc || !state->fb)
+		return -EINVAL;
+
+	memset(iter, 0, sizeof(*iter));
+	iter->clips = (struct drm_rect *)state->damage_clips->data;
+	iter->num_clips = state->num_clips;
+	iter->type = type;
+
+	/*
+	 * Full update in case of scaling or rotation. In future support for
+	 * scaling/rotating damage clips can be added
+	 */
+	if (state->crtc_w != (state->src_w >> 16) ||
+	    state->crtc_h != state->src_h >> 16 || state->rotation != 0) {
+		iter->curr_clip = iter->num_clips;
+		return 0;
+	}
+
+	iter->fb_src.x1 = 0;
+	iter->fb_src.y1 = 0;
+	iter->fb_src.x2 = state->fb->width;
+	iter->fb_src.y2 = state->fb->height;
+
+	iter->plane_src.x1 = state->src_x >> 16;
+	iter->plane_src.y1 = state->src_y >> 16;
+	iter->plane_src.x2 = iter->plane_src.x1 + (state->src_w >> 16);
+	iter->plane_src.y2 = iter->plane_src.y1 + (state->src_h >> 16);
+	iter->translate_plane_x = -iter->plane_src.x1;
+	iter->translate_plane_y = -iter->plane_src.y1;
+
+	/* Clip plane src rect to fb dimensions */
+	drm_rect_intersect(&iter->plane_src, &iter->fb_src);
+
+	iter->crtc_src.x1 = 0;
+	iter->crtc_src.y1 = 0;
+	iter->crtc_src.x2 = hdisplay;
+	iter->crtc_src.y2 = vdisplay;
+	iter->translate_crtc_x = -(iter->plane_src.x1 - state->crtc_x);
+	iter->translate_crtc_x = -(iter->plane_src.y1 - state->crtc_y);
+
+	/* Clip crtc src rect to plane dimensions */
+	drm_rect_translate(&iter->crtc_src, -iter->translate_crtc_x,
+			   -iter->translate_crtc_x);
+	drm_rect_intersect(&iter->crtc_src, &iter->plane_src);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_helper_damage_iter_init);
+
+/**
+ * drm_atomic_helper_damage_iter_next - advance the damage iterator
+ * @iter: The iterator to advance.
+ * @rect: Return a rectangle in coordinate specified during iterator init.
+ *
+ * Returns:  true if the output is valid, false if we've reached the end of the
+ * rectangle list. If the first call return false, means need full update.
+ */
+bool
+drm_atomic_helper_damage_iter_next(struct drm_atomic_helper_damage_iter *iter,
+				   struct drm_rect *rect)
+{
+	const struct drm_rect *curr_clip;
+
+next_clip:
+	if (iter->curr_clip >= iter->num_clips)
+		return false;
+
+	curr_clip = &iter->clips[iter->curr_clip];
+	iter->curr_clip++;
+
+	rect->x1 = curr_clip->x1;
+	rect->x2 = curr_clip->x2;
+	rect->y1 = curr_clip->y1;
+	rect->y2 = curr_clip->y2;
+
+	/* Clip damage rect within fb limit */
+	if (!drm_rect_intersect(rect, &iter->fb_src))
+		goto next_clip;
+	else if (iter->type & DRM_ATOMIC_HELPER_DAMAGE_CLIP_TYPE_FB)
+		return true;
+
+	/* Clip damage rect within plane limit */
+	if (!drm_rect_intersect(rect, &iter->plane_src))
+		goto next_clip;
+	else if (iter->type & DRM_ATOMIC_HELPER_DAMAGE_CLIP_TYPE_PLANE) {
+		drm_rect_translate(rect, iter->translate_plane_x,
+				   iter->translate_plane_y);
+		return true;
+	}
+
+	/* Clip damage rect within crtc limit */
+	if (!drm_rect_intersect(rect, &iter->crtc_src))
+		goto next_clip;
+
+	drm_rect_translate(rect, iter->translate_crtc_x,
+			   iter->translate_crtc_y);
+
+	return true;
+}
+EXPORT_SYMBOL(drm_atomic_helper_damage_iter_next);
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 26aaba5..ebd4b66 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -36,6 +36,37 @@ struct drm_atomic_state;
 struct drm_private_obj;
 struct drm_private_state;
 
+/**
+ * enum drm_atomic_helper_damage_clip_type - type of clips to iterator over
+ *
+ * While using drm_atomic_helper_damage_iter the type of clip coordinates caller
+ * is interested in.
+ */
+enum drm_atomic_helper_damage_clip_type {
+	DRM_ATOMIC_HELPER_DAMAGE_CLIP_TYPE_FB       = 0x0,
+	DRM_ATOMIC_HELPER_DAMAGE_CLIP_TYPE_PLANE    = 0x1,
+	DRM_ATOMIC_HELPER_DAMAGE_CLIP_TYPE_CRTC     = 0x2,
+};
+
+/**
+ * struct drm_atomic_helper_damage_iter - damage clip iterator
+ *
+ * This iterator tracks state needed to walk the list of damage clips.
+ */
+struct drm_atomic_helper_damage_iter {
+	enum drm_atomic_helper_damage_clip_type type;
+	const struct drm_rect *clips;
+	uint32_t num_clips;
+	uint32_t curr_clip;
+	struct drm_rect fb_src;
+	int translate_plane_x;
+	int translate_plane_y;
+	struct drm_rect plane_src;
+	int translate_crtc_x;
+	int translate_crtc_y;
+	struct drm_rect crtc_src;
+};
+
 int drm_atomic_helper_check_modeset(struct drm_device *dev,
 				struct drm_atomic_state *state);
 int drm_atomic_helper_check_plane_state(struct drm_plane_state *plane_state,
@@ -185,6 +216,14 @@ int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
 				       struct drm_modeset_acquire_ctx *ctx);
 void __drm_atomic_helper_private_obj_duplicate_state(struct drm_private_obj *obj,
 						     struct drm_private_state *state);
+int
+drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
+				   enum drm_atomic_helper_damage_clip_type type,
+				   const struct drm_plane_state *state,
+				   uint32_t hdisplay, uint32_t vdisplay);
+bool
+drm_atomic_helper_damage_iter_next(struct drm_atomic_helper_damage_iter *iter,
+				   struct drm_rect *rect);
 
 /**
  * drm_atomic_crtc_for_each_plane - iterate over planes currently attached to CRTC
-- 
2.7.4