fbdev: Support for byte-reversed framebuffer formats

Allow generic frame-buffer code to correctly write texts and blit images for
1, 2 and 4 bit per pixel frame-buffer organizations when pixels in bytes are
organized to in opposite order than bytes in long type.

Overhead should be reasonable.  If option is not selected, than compiler
should eliminate completely all overhead.

The feature is disabled at compile time if CONFIG_FB_CFB_REV_PIXELS_IN_BYTE is
not set.

[adaplas]
Convert helper functions to macros if feature is not enabled.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fb.h b/include/linux/fb.h
index cec54106aa87..b39395caa460 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -180,6 +180,7 @@ struct fb_bitfield {
 };
 
 #define FB_NONSTD_HAM           1       /* Hold-And-Modify (HAM)        */
+#define FB_NONSTD_REV_PIX_IN_B  2       /* order of pixels in each byte is reversed */
 
 #define FB_ACTIVATE_NOW         0       /* set values immediately (or vbl)*/
 #define FB_ACTIVATE_NXTOPEN     1       /* activate on next open        */