[PATCH 7/7] fbcon: Fix big-endian bogosity in slow_imageblit()

[PATCH 7/7] fbcon: Fix big-endian bogosity in slow_imageblit()

[Antonino A. Daplas]

The monochrome->color expansion routine that handles bitmaps which have
(widths % 8) != 0 (slow_imageblit) produces corrupt characters in big-endian.
This is caused by a bogus bit test in slow_imageblit().

Fix.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Acked-by: Herbert Poetzl <herbert@13thfloor.at>
---

This patch may deserve to go to the stable tree.  The code has already
been well tested in little-endian machines.  It's only in big-endian
where there is uncertainty and Herbert confirmed that this is the
correct way to go.

It should not introduce regressions.

Tony

 drivers/video/cfbimgblt.c |    2 +-
 include/linux/fb.h        |    2 --
 2 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/video/cfbimgblt.c b/drivers/video/cfbimgblt.c
index 910e233..8ba6152 100644
--- a/drivers/video/cfbimgblt.c
+++ b/drivers/video/cfbimgblt.c
@@ -169,7 +169,7 @@ static inline void slow_imageblit(const 
 
 		while (j--) {
 			l--;
-			color = (*s & 1 << (FB_BIT_NR(l))) ? fgcolor : bgcolor;
+			color = (*s & (1 << l)) ? fgcolor : bgcolor;
 			val |= FB_SHIFT_HIGH(color, shift);
 			
 			/* Did the bitshift spill bits to the next long? */
diff --git a/include/linux/fb.h b/include/linux/fb.h
index d03fadf..315d897 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -839,12 +839,10 @@ struct fb_info {
 #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
 
     /*



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Re: [stable] [PATCH 7/7] fbcon: Fix big-endian bogosity in slow_imageblit()

[Greg KH]

On Mon, Mar 27, 2006 at 09:11:44PM +0800, Antonino A. Daplas wrote:
> The monochrome->color expansion routine that handles bitmaps which have
> (widths % 8) != 0 (slow_imageblit) produces corrupt characters in big-endian.
> This is caused by a bogus bit test in slow_imageblit().

queued to -stable, thanks.

greg k-h



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