Thread (4 messages) 4 messages, 2 authors, 1d ago
WARM1d

[PATCH] staging: sm750fb: fix mono image source stride mismatch in lynxfb_ops_imageblit()

From: Muhammad Bilal <hidden>
Date: 2026-07-18 04:57:10
Also in: linux-staging, lkml
Subsystem: staging - silicon motion sm750 frame buffer driver, staging subsystem, the rest · Maintainers: Sudip Mukherjee, Teddy Wang, Greg Kroah-Hartman, Linus Torvalds

sm750_hw_imageblit() advances its monochrome source pointer by
src_delta per scanline, and computes the correct rounded-up stride
internally as:

	bytes_per_scan = (width + start_bit + 7) / 8;

Its only caller, lynxfb_ops_imageblit(), instead passes src_delta as
image->width >> 3. For widths not a multiple of 8 this under-counts
the stride, so the source pointer falls further behind the real
per-scanline layout on every line, corrupting the rendered image.

Use DIV_ROUND_UP() so the stride passed in matches what
sm750_hw_imageblit() already assumes.

Signed-off-by: Muhammad Bilal <redacted>
---
 drivers/staging/sm750fb/sm750.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/staging/sm750fb/sm750.c b/drivers/staging/sm750fb/sm750.c
index 89c811e0806c..69e803f4f175 100644
--- a/drivers/staging/sm750fb/sm750.c
+++ b/drivers/staging/sm750fb/sm750.c
@@ -261,7 +261,7 @@ static void lynxfb_ops_imageblit(struct fb_info *info,
 	spin_lock(&sm750_dev->slock);
 
 	sm750_dev->accel.de_imageblit(&sm750_dev->accel,
-				      image->data, image->width >> 3, 0,
+				      image->data, DIV_ROUND_UP(image->width, 8), 0,
 				      base, pitch, bpp,
 				      image->dx, image->dy,
 				      image->width, image->height,
-- 
2.55.0
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help