drm/ssd130x: Iterate over damage clips instead of using a merged rect

The drm_atomic_helper_damage_merged() helper merges all the damage clips
into one rectangle. If there are multiple damage clips that aren't close
to each other, the resulting rectangle could be quite big.

Instead of using that function helper, iterate over all the damage clips
and update them one by one.
Suggested-by: Jocelyn Falempe <jfalempe@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220930152944.2584356-1-javierm@redhat.com

drivers/gpu/drm/solomon/ssd130x.c

@@ -578,21 +578,24 @@ static void ssd130x_primary_plane_helper_atomic_update(struct drm_plane *plane,
 	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
 	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_atomic_helper_damage_iter iter;
 	struct drm_device *drm = plane->dev;
-	struct drm_rect src_clip, dst_clip;
+	struct drm_rect dst_clip;
+	struct drm_rect damage;
 	int idx;
 
-	if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &src_clip))
+	if (!drm_dev_enter(drm, &idx))
 		return;
 
-	dst_clip = plane_state->dst;
-	if (!drm_rect_intersect(&dst_clip, &src_clip))
-		return;
+	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+	drm_atomic_for_each_plane_damage(&iter, &damage) {
+		dst_clip = plane_state->dst;
 
-	if (!drm_dev_enter(drm, &idx))
-		return;
+		if (!drm_rect_intersect(&dst_clip, &damage))
+			continue;
 
-	ssd130x_fb_blit_rect(plane_state->fb, &shadow_plane_state->data[0], &dst_clip);
+		ssd130x_fb_blit_rect(plane_state->fb, &shadow_plane_state->data[0], &dst_clip);
+	}
 
 	drm_dev_exit(idx);
 }