1 =============================
2 Frame Buffer device internals
3 =============================
4
5 This is a first start for some documentation a
6 internals.
7
8 Authors:
9
10 - Geert Uytterhoeven <geert@linux-m68k.org>, 21
11 - James Simmons <jsimmons@user.sf.net>, Nov 26
12
13 ----------------------------------------------
14
15 Structures used by the frame buffer device API
16 ==============================================
17
18 The following structures play a role in the ga
19 are defined in <linux/fb.h>.
20
21 1. Outside the kernel (user space)
22
23 - struct fb_fix_screeninfo
24
25 Device independent unchangeable informatio
26 a specific video mode. This can be obtaine
27 ioctl.
28
29 - struct fb_var_screeninfo
30
31 Device independent changeable information
32 specific video mode. This can be obtained
33 ioctl, and updated with the FBIOPUT_VSCREE
34 the screen only, you can use the FBIOPAN_D
35
36 - struct fb_cmap
37
38 Device independent colormap information. Y
39 using the FBIOGETCMAP and FBIOPUTCMAP ioct
40
41
42 2. Inside the kernel
43
44 - struct fb_info
45
46 Generic information, API and low level inf
47 buffer device instance (slot number, board
48
49 - struct `par`
50
51 Device dependent information that uniquely
52 particular piece of hardware.
53
54
55 Visuals used by the frame buffer device API
56 ===========================================
57
58
59 Monochrome (FB_VISUAL_MONO01 and FB_VISUAL_MON
60 ----------------------------------------------
61 Each pixel is either black or white.
62
63
64 Pseudo color (FB_VISUAL_PSEUDOCOLOR and FB_VIS
65 ----------------------------------------------
66 The whole pixel value is fed through a program
67 color (including red, green, and blue intensit
68 value, and that color is displayed.
69
70
71 True color (FB_VISUAL_TRUECOLOR)
72 --------------------------------
73 The pixel value is broken up into red, green,
74
75
76 Direct color (FB_VISUAL_DIRECTCOLOR)
77 ------------------------------------
78 The pixel value is broken up into red, green,
79 are looked up in separate red, green, and blue
80
81
82 Grayscale displays
83 ------------------
84 Grayscale and static grayscale are special var
85 pseudo color, where the red, green and blue co
86 each other.
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