From: Franck Bui-Huu <[email protected]>
It seems that this piece of code has already been fixed twice...
The first fix has been made by the following commit:
81d3e147ec9ffc6ef04b5f05afa4bef22487b32b
by introducing FB_BIT_NR() macro to fix a 'potential' endianess
bug. It appears that change was broken for big endian platforms,
but I suspect it was for little-endian ones too.
Then a second fix has been made to fix the previous change for
big-endian platform, see commit:
a536093a2f07007aa572e922752b7491b9ea8ff2
This commit actually reverted the first fix and thus makes the
big-endian case works but leaves the little-endian case broken.
Therefore it seems that the very first state was broken only
on little-endian platform...
This patch is the third and hopefully the last attempt to fix
this bug correctly. It restores the first fix _and_ swaps the
little-endian and bit-endian implementations of FB_BIT_NR().
Now, it should work for both endianness but has been tested on
little-endian machine only.
Signed-off-by: Franck Bui-Huu <[email protected]>
---
Same patch with change log updated.
drivers/video/cfbimgblt.c | 4 ++--
include/linux/fb.h | 2 ++
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/video/cfbimgblt.c b/drivers/video/cfbimgblt.c
index 51d3538..8f47bf4 100644
--- a/drivers/video/cfbimgblt.c
+++ b/drivers/video/cfbimgblt.c
@@ -168,7 +168,7 @@ static inline void slow_imageblit(const
while (j--) {
l--;
- color = (*s & (1 << l)) ? fgcolor : bgcolor;
+ color = (*s & (1 << FB_BIT_NR(l))) ? fgcolor : bgcolor;
val |= FB_SHIFT_HIGH(color, shift);
/* Did the bitshift spill bits to the next long? */
@@ -258,7 +258,7 @@ static inline void fast_imageblit(const
s += spitch;
}
}
-
+
void cfb_imageblit(struct fb_info *p, const struct fb_image *image)
{
u32 fgcolor, bgcolor, start_index, bitstart, pitch_index = 0;
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 3e69241..6ca18b8 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -854,10 +854,12 @@ struct fb_info {
#endif
#if defined (__BIG_ENDIAN)
+#define FB_BIT_NR(b) (b)
#define FB_LEFT_POS(bpp) (32 - bpp)
#define FB_SHIFT_HIGH(val, bits) ((val) >> (bits))
#define FB_SHIFT_LOW(val, bits) ((val) << (bits))
#else
+#define FB_BIT_NR(b) (7 - (b))
#define FB_LEFT_POS(bpp) (0)
#define FB_SHIFT_HIGH(val, bits) ((val) << (bits))
#define FB_SHIFT_LOW(val, bits) ((val) >> (bits))
--
1.4.3.4
-
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