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fbdev: atafb: Restrict SuperBlitter to supported formats

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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.

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: d463633d63 ("fbdev: atafb: Add support for SuperVidel's SuperBlitter")
Signed-off-by: Linmao Li <lilinmao@kylinos.cn>
Tested-by: Miro Kropáček <miro.kropacek@gmail.com>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Linmao Li 2026-08-27 17:39:48 +08:00 committed by Helge Deller
parent 3fb13d29cf
commit 3934185ba6
1 changed files with 5 additions and 1 deletions
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6
drivers/video/fbdev/atafb.c
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@ -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;