[PATCH] fbdev: Fix incorrect unaligned access in little-endian machines

The drawing function cfbfillrect does not work correctly when access is not
unsigned-long aligned.  It manifests as extra lines of pixels that are not
complete drawn.  Reversing the shift operator solves the problem, so I would
presume that this bug would manifest only on little endian machines.  The
function cfbcopyarea may also have this bug.

Aligned access should present no problems.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/fb.h b/include/linux/fb.h
index dab3a4decb44..a973be2cfe61 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -835,6 +835,18 @@ struct fb_info {
 
 #endif
 
+#if defined (__BIG_ENDIAN)
+#define FB_LEFT_POS(bpp)          (32 - bpp)
+#define FB_SHIFT_HIGH(val, bits)  ((val) >> (bits))
+#define FB_SHIFT_LOW(val, bits)   ((val) << (bits))
+#define FB_BIT_NR(b)              (7 - (b))
+#else
+#define FB_LEFT_POS(bpp)          (0)
+#define FB_SHIFT_HIGH(val, bits)  ((val) << (bits))
+#define FB_SHIFT_LOW(val, bits)   ((val) >> (bits))
+#define FB_BIT_NR(b)              (b)
+#endif
+
     /*
      *  `Generic' versions of the frame buffer device operations
      */