[PATCH v2 6/7] 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 <ag...@csgraf.de>
Reported-by: Da Xue <da@libre.computer>

---

v1 -> v2:

  - Fix dcache range; we were flushing too much before
  - Remove ifdefs
---
 drivers/video/video-uclass.c | 51 ++++++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 66df4c97ef..95126b9bdb 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -223,9 +223,45 @@ int video_damage(struct udevice *vid, int x, int y, int 
width, int height)
        return 0;
 }
 
+#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;
+
+       if (!CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
+               flush_dcache_range((ulong)priv->fb,
+                                  ALIGN((ulong)priv->fb + priv->fb_size,
+                                        CONFIG_SYS_CACHELINE_SIZE));
+
+               return;
+       }
+
+       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 - lstart;
+
+                       start = ALIGN_DOWN(start, CONFIG_SYS_CACHELINE_SIZE);
+                       end = ALIGN(end, CONFIG_SYS_CACHELINE_SIZE);
+
+                       flush_dcache_range(start, end);
+               }
+       }
+}
+#endif
+
 /* Flush video activity to the caches */
 int video_sync(struct udevice *vid, bool force)
 {
+       struct video_priv *priv = dev_get_uclass_priv(vid);
        struct video_ops *ops = video_get_ops(vid);
        int ret;
 
@@ -241,15 +277,8 @@ 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;
 
        if (force || get_timer(last_sync) > 100) {
@@ -257,6 +286,12 @@ int video_sync(struct udevice *vid, bool force)
                last_sync = get_timer(0);
        }
 #endif
+
+       if (CONFIG_IS_ENABLED(VIDEO_DAMAGE)) {
+               priv->damage.endx = 0;
+               priv->damage.endy = 0;
+       }
+
        return 0;
 }
 
-- 
2.32.1 (Apple Git-133)