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-rw-r--r--drivers/video/skeletonfb.c8
-rw-r--r--drivers/video/vfb.c11
-rw-r--r--include/linux/fb.h8
3 files changed, 18 insertions, 9 deletions
diff --git a/drivers/video/skeletonfb.c b/drivers/video/skeletonfb.c
index a439159..89158bc 100644
--- a/drivers/video/skeletonfb.c
+++ b/drivers/video/skeletonfb.c
@@ -308,9 +308,11 @@ static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
* color depth = SUM(var->{color}.length)
*
* Pseudocolor:
- * var->{color}.offset is 0
- * var->{color}.length contains width of DAC or the number of unique
- * colors available (color depth)
+ * var->{color}.offset is 0 unless the palette index takes less than
+ * bits_per_pixel bits and is stored in the upper
+ * bits of the pixel value
+ * var->{color}.length is set so that 1 << length is the number of
+ * available palette entries
* pseudo_palette is not used
* RAMDAC[X] is programmed to (red, green, blue)
* color depth = var->{color}.length
diff --git a/drivers/video/vfb.c b/drivers/video/vfb.c
index cc919ae..050d432 100644
--- a/drivers/video/vfb.c
+++ b/drivers/video/vfb.c
@@ -318,13 +318,16 @@ static int vfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
* {hardwarespecific} contains width of RAMDAC
* cmap[X] is programmed to (X << red.offset) | (X << green.offset) | (X << blue.offset)
* RAMDAC[X] is programmed to (red, green, blue)
- *
+ *
* Pseudocolor:
- * uses offset = 0 && length = RAMDAC register width.
- * var->{color}.offset is 0
- * var->{color}.length contains widht of DAC
+ * var->{color}.offset is 0 unless the palette index takes less than
+ * bits_per_pixel bits and is stored in the upper
+ * bits of the pixel value
+ * var->{color}.length is set so that 1 << length is the number of available
+ * palette entries
* cmap is not used
* RAMDAC[X] is programmed to (red, green, blue)
+ *
* Truecolor:
* does not use DAC. Usually 3 are present.
* var->{color}.offset contains start of bitfield
diff --git a/include/linux/fb.h b/include/linux/fb.h
index f563c50..330c4b1 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 */
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