Hi Linmao,
thanks for your patch!
Am 27.08.2026 um 21:39 schrieb Linmao Li:
The SuperBlitter operations derive an integer byte count per pixel. The
accelerated fill path handles only one-, two- and four-byte pixels.
However, the operations are currently installed for every external
framebuffer in SuperVidel RAM, including planar 1/2/4/8-bpp and 24-bpp
truecolor modes accepted by the external video parser.
For 1/2/4-bpp modes, the byte count becomes zero, so accelerated copies do
nothing and fills fall through to 32-bit stores. Planar 8-bpp uses an
incompatible memory layout. For 24-bpp modes, fills also use 32-bit stores
despite advancing addresses by three bytes per pixel. These cases can
corrupt the framebuffer beyond the requested rectangle.
I believe 24 bpp mode can be rescued using something like this (entirely
untested):
--- a/drivers/video/fbdev/atafb.c
+++ b/drivers/video/fbdev/atafb.c
@@ -2463,6 +2463,11 @@ static void svblit_fillrect(struct fb_info *info,
case 2:
memset16((u16 *)line, pix, rect->width);
break;
+ case 3:
+ memset(line, pix, ((rect->width * bytespp) % 4));
+ line += ((rect->width * bytespp) % 4);
+ memset32((u32 *)line, pix, (rect->width * bytespp) / 4);
+ break;
default:
memset32((u32 *)line, pix, rect->width);
break;
Can't test this on hardware, and would need Miro to confirm it works as
intended.
Enable the SuperBlitter operations only for the layouts they implement:
8-bpp packed pixels and 16/32-bpp truecolor. Keep the existing software
operations for all other external formats.
Fixes: d463633d63e6 ("fbdev: atafb: Add support for SuperVidel's SuperBlitter")
Signed-off-by: Linmao Li <[email protected]>
---
drivers/video/fbdev/atafb.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c
index 5bca34c45cef3..c3011b61a94b9 100644
--- a/drivers/video/fbdev/atafb.c
+++ b/drivers/video/fbdev/atafb.c
@@ -3360,7 +3360,11 @@ static int __init atafb_probe(struct platform_device
*pdev)
memset (screen_base, 0, external_len);
/* framebuffer in SV RAM: enable the SuperBlitter */
- if (external_addr >= 0xa0000000) {
+ if (external_addr >= 0xa0000000 &&
+ ((external_pmode == FB_TYPE_PACKED_PIXELS &&
+ external_depth == 8) ||
+ (external_pmode == -1 &&
+ (external_depth == 16 || external_depth == 32)))) {
svblit_regs = ioremap(SVBLIT_REGS_PHYS, 0x100);
if (svblit_regs) {
svblit_fw = svblit_rd(SVBLIT_VERSION) & 0x1ff;
Otherwise, LGTM.
@Geert: can you remember if pixel format or bit depth of an external
framebuffer can be changed at runtime using fbset??
Reviewed-by: Michael Schmitz <[email protected]>
