fbdev: fix color component field length documentation

The documentation about the meaning of the color component bitfield
lengths in pseudocolor modes is inconsistent.  Fix it, so that it
indicates the correct interpretation everywhere, i.e.  that 1 << length is
the number of palette entries.

Signed-off-by: Michal Januszewski <spock@gentoo.org>
Acked-by: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <syrjala@sci.fi>
Acked-by: Geert Uytterhoeven <geert.uytterhoeven@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/fb.h b/include/linux/fb.h
index f563c501393..330c4b1bfca 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -173,8 +173,12 @@ struct fb_fix_screeninfo {
 /* Interpretation of offset for color fields: All offsets are from the right,
  * inside a "pixel" value, which is exactly 'bits_per_pixel' wide (means: you
  * can use the offset as right argument to <<). A pixel afterwards is a bit
- * stream and is written to video memory as that unmodified. This implies
- * big-endian byte order if bits_per_pixel is greater than 8.
+ * stream and is written to video memory as that unmodified.
+ *
+ * For pseudocolor: offset and length should be the same for all color
+ * components. Offset specifies the position of the least significant bit
+ * of the pallette index in a pixel value. Length indicates the number
+ * of available palette entries (i.e. # of entries = 1 << length).
  */
 struct fb_bitfield {
         __u32 offset;                   /* beginning of bitfield        */