[PATCH 6/6] video: Only dcache flush damaged lines

[Alexander Graf]

Now that we have a damage area tells us which parts of the frame buffer
actually need updating, let's only dcache flush those on video_sync()
calls. With this optimization in place, frame buffer updates - especially
on large screen such as 4k displays - speed up significantly.

Signed-off-by: Alexander Graf <agraf at csgraf.de>
Reported-by: Da Xue <da at libre.computer>
---
 drivers/video/video-uclass.c | 49 ++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 9ac1974670..5661beea38 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -222,6 +222,39 @@ int video_damage(struct udevice *vid, int x, int y, int width, int height)
 }
 #endif
 
+#if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
+static void video_flush_dcache(struct udevice *vid)
+{
+	struct video_priv *priv = dev_get_uclass_priv(vid);
+
+	if (!priv->flush_dcache)
+		return;
+
+#ifdef CONFIG_VIDEO_DAMAGE
+	if (priv->damage.endx && priv->damage.endy) {
+		int lstart = priv->damage.x * VNBYTES(priv->bpix);
+		int lend = priv->damage.endx * VNBYTES(priv->bpix);
+		int y;
+
+		for (y = priv->damage.y; y < priv->damage.endy; y++) {
+			ulong fb = (ulong)priv->fb;
+			ulong start = fb + (y * priv->line_length) + lstart;
+			ulong end = start + lend;
+
+			start = ALIGN_DOWN(start, CONFIG_SYS_CACHELINE_SIZE);
+			end = ALIGN(end, CONFIG_SYS_CACHELINE_SIZE);
+
+			flush_dcache_range(start, end);
+		}
+	}
+#else
+	flush_dcache_range((ulong)priv->fb,
+			   ALIGN((ulong)priv->fb + priv->fb_size,
+				 CONFIG_SYS_CACHELINE_SIZE));
+#endif
+}
+#endif
+
 /* Flush video activity to the caches */
 int video_sync(struct udevice *vid, bool force)
 {
@@ -240,13 +273,7 @@ int video_sync(struct udevice *vid, bool force)
 	 * out whether it exists? For now, ARM is safe.
 	 */
 #if defined(CONFIG_ARM) && !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
-	struct video_priv *priv = dev_get_uclass_priv(vid);
-
-	if (priv->flush_dcache) {
-		flush_dcache_range((ulong)priv->fb,
-				   ALIGN((ulong)priv->fb + priv->fb_size,
-					 CONFIG_SYS_CACHELINE_SIZE));
-	}
+	video_flush_dcache(vid);
 #elif defined(CONFIG_VIDEO_SANDBOX_SDL)
 	struct video_priv *priv = dev_get_uclass_priv(vid);
 	static ulong last_sync;
@@ -256,6 +283,14 @@ int video_sync(struct udevice *vid, bool force)
 		last_sync = get_timer(0);
 	}
 #endif
+
+#ifdef CONFIG_VIDEO_DAMAGE
+	struct video_priv *priv = dev_get_uclass_priv(vid);
+
+	priv->damage.endx = 0;
+	priv->damage.endy = 0;
+#endif
+
 	return 0;
 }
 
-- 
2.32.1 (Apple Git-133)