Disable ywrap if not supported by fbcon scrolling code

PATCH In review Knut Petersen 2 participants 2 messages Dec 13, 2005

Subsystems (2)

Framebuffer layer Console

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Knut Petersen

author

2005-12-13 13:29 UTC #0 lore raw

PATCH 1/1 Disable ywrap if not supported by fbcon scrolling code

updatescrollmode() must not select ywrap scrolling if divides(vc->vc_font.height, yres) is not true as this is not supported by the actual ywrap scrolling code.

The bug is triggered with e.g. mode 800x600, vxres 1024, vyres 8192, bpp 8, font dimensions 8x16, 8Mb video ram and FBINFO_HWACCEL_YWRAP set. If those conditions are met, scrolling is broken and garbage is permanently displayed at the bottom of the screen.

No regression, no possible side effects.

Definitely needed by cyblafb and probably needed by amifb.

Signed-off-by Knut Petersen <[email protected]>

drivers/video/console/fbcon.c +0 -0

diff -uprN -X linux/Documentation/dontdiff -x '*.bak' -x '*.ctx' linuxorig/drivers/video/console/fbcon.c linux/drivers/video/console/fbcon.c
@@ -1968,7 +1968,8 @@ static __inline__ void updatescrollmode(

		divides(ypan, vc->vc_font.height) && vyres > yres;
	int good_wrap = (cap & FBINFO_HWACCEL_YWRAP) &&
		divides(ywrap, vc->vc_font.height) &&
-		divides(vc->vc_font.height, vyres);
+		divides(vc->vc_font.height, vyres) &&
+		divides(vc->vc_font.height, yres);
	int reading_fast = cap & FBINFO_READS_FAST;
	int fast_copyarea = (cap & FBINFO_HWACCEL_COPYAREA) &&
		!(cap & FBINFO_HWACCEL_DISABLED);

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Antonino A. Daplas

Acked-by Antonino Daplas on v1 1/1

2005-12-13 15:44 UTC #1 lore raw

Quoted 10 lines · Knut Petersen

updatescrollmode() must not select ywrap scrolling if divides(vc->vc_font.height, yres) is not true as this is not supported by the actual ywrap scrolling code.
The bug is triggered with e.g. mode 800x600, vxres 1024, vyres 8192, bpp 8, font dimensions 8x16, 8Mb video ram and FBINFO_HWACCEL_YWRAP set. If those conditions are met, scrolling is broken and garbage is permanently displayed at the bottom of the screen.

Quoted 5 lines

No regression, no possible side effects.
Definitely needed by cyblafb and probably needed by amifb.
Signed-off-by Knut Petersen <[email protected]>

Acked-by Antonino Daplas <[email protected]>