mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-29 15:43:59 +08:00
de7c6d15e3
Implement support for the E-Ink Metronome controller. It provides an mmapable interface to the controller using defio support. It was tested with a gumstix pxa255 with Vizplex media using Xfbdev and various X clients such as xeyes, xpdf, xloadimage. This patch also fixes the following bug: Defio would cause a hang on write access to the framebuffer as the page fault would be called ad-infinitum. It fixes fb_defio by setting the mapping to be used by page_mkclean. Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com> Cc: "Antonino A. Daplas" <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
54 lines
1.9 KiB
Plaintext
54 lines
1.9 KiB
Plaintext
Understanding fbdev's cmap
|
|
--------------------------
|
|
|
|
These notes explain how X's dix layer uses fbdev's cmap structures.
|
|
|
|
*. example of relevant structures in fbdev as used for a 3-bit grayscale cmap
|
|
struct fb_var_screeninfo {
|
|
.bits_per_pixel = 8,
|
|
.grayscale = 1,
|
|
.red = { 4, 3, 0 },
|
|
.green = { 0, 0, 0 },
|
|
.blue = { 0, 0, 0 },
|
|
}
|
|
struct fb_fix_screeninfo {
|
|
.visual = FB_VISUAL_STATIC_PSEUDOCOLOR,
|
|
}
|
|
for (i = 0; i < 8; i++)
|
|
info->cmap.red[i] = (((2*i)+1)*(0xFFFF))/16;
|
|
memcpy(info->cmap.green, info->cmap.red, sizeof(u16)*8);
|
|
memcpy(info->cmap.blue, info->cmap.red, sizeof(u16)*8);
|
|
|
|
*. X11 apps do something like the following when trying to use grayscale.
|
|
for (i=0; i < 8; i++) {
|
|
char colorspec[64];
|
|
memset(colorspec,0,64);
|
|
sprintf(colorspec, "rgb:%x/%x/%x", i*36,i*36,i*36);
|
|
if (!XParseColor(outputDisplay, testColormap, colorspec, &wantedColor))
|
|
printf("Can't get color %s\n",colorspec);
|
|
XAllocColor(outputDisplay, testColormap, &wantedColor);
|
|
grays[i] = wantedColor;
|
|
}
|
|
There's also named equivalents like gray1..x provided you have an rgb.txt.
|
|
|
|
Somewhere in X's callchain, this results in a call to X code that handles the
|
|
colormap. For example, Xfbdev hits the following:
|
|
|
|
xc-011010/programs/Xserver/dix/colormap.c:
|
|
|
|
FindBestPixel(pentFirst, size, prgb, channel)
|
|
|
|
dr = (long) pent->co.local.red - prgb->red;
|
|
dg = (long) pent->co.local.green - prgb->green;
|
|
db = (long) pent->co.local.blue - prgb->blue;
|
|
sq = dr * dr;
|
|
UnsignedToBigNum (sq, &sum);
|
|
BigNumAdd (&sum, &temp, &sum);
|
|
|
|
co.local.red are entries that were brought in through FBIOGETCMAP which come
|
|
directly from the info->cmap.red that was listed above. The prgb is the rgb
|
|
that the app wants to match to. The above code is doing what looks like a least
|
|
squares matching function. That's why the cmap entries can't be set to the left
|
|
hand side boundaries of a color range.
|
|
|