diff mbox series

[Concept,08/24] video: Optimise video_flush_copy() for full-line damage

Message ID 20260103011908.149445-9-sjg@u-boot.org
State New
Headers
Series Malloc debugging and test/py improvements |

Commit Message

Simon Glass Jan. 3, 2026, 1:18 a.m. UTC 
  From: Simon Glass <simon.glass@canonical.com>

When copying partial framebuffer regions line by line, there is overhead
from multiple memcpy() calls.

Optimise video_flush_copy() to detect when entire lines are being copied
(damage spans full width) and perform a single memcpy() for the whole
region instead of looping line by line.

Also invert the early-exit check to reduce nesting.

Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
---

 drivers/video/video-uclass.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c
index 3e02c48d399..698fe0e4caf 100644
--- a/drivers/video/video-uclass.c
+++ b/drivers/video/video-uclass.c
@@ -507,16 +507,25 @@  static void video_flush_copy(struct udevice *vid)
 	if (!priv->copy_fb)
 		return;
 
-	if (damage->x1 && damage->y1) {
-		int lstart = damage->x0 * VNBYTES(priv->bpix);
-		int lend = damage->x1 * VNBYTES(priv->bpix);
+	if (!damage->x1 || !damage->y1)
+		return;
+
+	int lstart = damage->x0 * VNBYTES(priv->bpix);
+	int llen = damage->x1 * VNBYTES(priv->bpix) - lstart;
+
+	/* Copy entire region at once if full lines are damaged */
+	if (!lstart && llen == priv->line_length) {
+		ulong offset = damage->y0 * priv->line_length;
+		ulong len = (damage->y1 - damage->y0) * priv->line_length;
+
+		memcpy(priv->copy_fb + offset, priv->fb + offset, len);
+	} else {
 		int y;
 
 		for (y = damage->y0; y < damage->y1; y++) {
-			ulong offset = (y * priv->line_length) + lstart;
-			ulong len = lend - lstart;
+			ulong offset = y * priv->line_length + lstart;
 
-			memcpy(priv->copy_fb + offset, priv->fb + offset, len);
+			memcpy(priv->copy_fb + offset, priv->fb + offset, llen);
 		}
 	}
 }