linux-kernel - [PATCH v2] drm/ssd130x: Iterate over damage clips instead of using a merged rect

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Date:   Fri, 30 Sep 2022 17:29:44 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Zimmermann <tzimmermann@...e.de>,
        Jocelyn Falempe <jfalempe@...hat.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH v2] 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@...hat.com>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
---

Changes in v2:
- Move the dst_clip assignment inside the drm_atomic_for_each_plane_damage()
  loop (Thomas Zimmermann).
- Pass dst_clip instead of damage area as argument to ssd130x_fb_blit_rect()
  function (Thomas Zimmermann)

 drivers/gpu/drm/solomon/ssd130x.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index bc41a5ae810a..f456b233d2e7 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/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);
 }
-- 
2.37.3