xref: /openbmc/linux/Documentation/fb/vt8623fb.rst (revision 0898782247ae533d1f4e47a06bc5d4870931b284)
1*ab42b818SMauro Carvalho Chehab===============================================================
2*ab42b818SMauro Carvalho Chehabvt8623fb - fbdev driver for graphics core in VIA VT8623 chipset
3*ab42b818SMauro Carvalho Chehab===============================================================
4*ab42b818SMauro Carvalho Chehab
5*ab42b818SMauro Carvalho Chehab
6*ab42b818SMauro Carvalho ChehabSupported Hardware
7*ab42b818SMauro Carvalho Chehab==================
8*ab42b818SMauro Carvalho Chehab
9*ab42b818SMauro Carvalho ChehabVIA VT8623 [CLE266] chipset and	its graphics core
10*ab42b818SMauro Carvalho Chehab(known as CastleRock or Unichrome)
11*ab42b818SMauro Carvalho Chehab
12*ab42b818SMauro Carvalho ChehabI tested vt8623fb on VIA EPIA ML-6000
13*ab42b818SMauro Carvalho Chehab
14*ab42b818SMauro Carvalho Chehab
15*ab42b818SMauro Carvalho ChehabSupported Features
16*ab42b818SMauro Carvalho Chehab==================
17*ab42b818SMauro Carvalho Chehab
18*ab42b818SMauro Carvalho Chehab	*  4 bpp pseudocolor modes (with 18bit palette, two variants)
19*ab42b818SMauro Carvalho Chehab	*  8 bpp pseudocolor mode (with 18bit palette)
20*ab42b818SMauro Carvalho Chehab	* 16 bpp truecolor mode (RGB 565)
21*ab42b818SMauro Carvalho Chehab	* 32 bpp truecolor mode (RGB 888)
22*ab42b818SMauro Carvalho Chehab	* text mode (activated by bpp = 0)
23*ab42b818SMauro Carvalho Chehab	* doublescan mode variant (not available in text mode)
24*ab42b818SMauro Carvalho Chehab	* panning in both directions
25*ab42b818SMauro Carvalho Chehab	* suspend/resume support
26*ab42b818SMauro Carvalho Chehab	* DPMS support
27*ab42b818SMauro Carvalho Chehab
28*ab42b818SMauro Carvalho ChehabText mode is supported even in higher resolutions, but there is limitation to
29*ab42b818SMauro Carvalho Chehablower pixclocks (maximum about 100 MHz). This limitation is not enforced by
30*ab42b818SMauro Carvalho Chehabdriver. Text mode supports 8bit wide fonts only (hardware limitation) and
31*ab42b818SMauro Carvalho Chehab16bit tall fonts (driver limitation).
32*ab42b818SMauro Carvalho Chehab
33*ab42b818SMauro Carvalho ChehabThere are two 4 bpp modes. First mode (selected if nonstd == 0) is mode with
34*ab42b818SMauro Carvalho Chehabpacked pixels, high nibble first. Second mode (selected if nonstd == 1) is mode
35*ab42b818SMauro Carvalho Chehabwith interleaved planes (1 byte interleave), MSB first. Both modes support
36*ab42b818SMauro Carvalho Chehab8bit wide fonts only (driver limitation).
37*ab42b818SMauro Carvalho Chehab
38*ab42b818SMauro Carvalho ChehabSuspend/resume works on systems that initialize video card during resume and
39*ab42b818SMauro Carvalho Chehabif device is active (for example used by fbcon).
40*ab42b818SMauro Carvalho Chehab
41*ab42b818SMauro Carvalho Chehab
42*ab42b818SMauro Carvalho ChehabMissing Features
43*ab42b818SMauro Carvalho Chehab================
44*ab42b818SMauro Carvalho Chehab(alias TODO list)
45*ab42b818SMauro Carvalho Chehab
46*ab42b818SMauro Carvalho Chehab	* secondary (not initialized by BIOS) device support
47*ab42b818SMauro Carvalho Chehab	* MMIO support
48*ab42b818SMauro Carvalho Chehab	* interlaced mode variant
49*ab42b818SMauro Carvalho Chehab	* support for fontwidths != 8 in 4 bpp modes
50*ab42b818SMauro Carvalho Chehab	* support for fontheight != 16 in text mode
51*ab42b818SMauro Carvalho Chehab	* hardware cursor
52*ab42b818SMauro Carvalho Chehab	* video overlay support
53*ab42b818SMauro Carvalho Chehab	* vsync synchronization
54*ab42b818SMauro Carvalho Chehab	* acceleration support (8514-like 2D, busmaster transfers)
55*ab42b818SMauro Carvalho Chehab
56*ab42b818SMauro Carvalho Chehab
57*ab42b818SMauro Carvalho ChehabKnown bugs
58*ab42b818SMauro Carvalho Chehab==========
59*ab42b818SMauro Carvalho Chehab
60*ab42b818SMauro Carvalho Chehab	* cursor disable in text mode doesn't work
61*ab42b818SMauro Carvalho Chehab
62*ab42b818SMauro Carvalho Chehab
63*ab42b818SMauro Carvalho Chehab--
64*ab42b818SMauro Carvalho ChehabOndrej Zajicek <santiago@crfreenet.org>
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