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diff --git a/Documentation/fb/vt8623fb.rst b/Documentation/fb/vt8623fb.rst new file mode 100644 index 000000000..ba1730937 --- /dev/null +++ b/Documentation/fb/vt8623fb.rst @@ -0,0 +1,64 @@ +=============================================================== +vt8623fb - fbdev driver for graphics core in VIA VT8623 chipset +=============================================================== + + +Supported Hardware +================== + +VIA VT8623 [CLE266] chipset and its graphics core +(known as CastleRock or Unichrome) + +I tested vt8623fb on VIA EPIA ML-6000 + + +Supported Features +================== + + * 4 bpp pseudocolor modes (with 18bit palette, two variants) + * 8 bpp pseudocolor mode (with 18bit palette) + * 16 bpp truecolor mode (RGB 565) + * 32 bpp truecolor mode (RGB 888) + * text mode (activated by bpp = 0) + * doublescan mode variant (not available in text mode) + * panning in both directions + * suspend/resume support + * DPMS support + +Text mode is supported even in higher resolutions, but there is limitation to +lower pixclocks (maximum about 100 MHz). This limitation is not enforced by +driver. Text mode supports 8bit wide fonts only (hardware limitation) and +16bit tall fonts (driver limitation). + +There are two 4 bpp modes. First mode (selected if nonstd == 0) is mode with +packed pixels, high nibble first. Second mode (selected if nonstd == 1) is mode +with interleaved planes (1 byte interleave), MSB first. Both modes support +8bit wide fonts only (driver limitation). + +Suspend/resume works on systems that initialize video card during resume and +if device is active (for example used by fbcon). + + +Missing Features +================ +(alias TODO list) + + * secondary (not initialized by BIOS) device support + * MMIO support + * interlaced mode variant + * support for fontwidths != 8 in 4 bpp modes + * support for fontheight != 16 in text mode + * hardware cursor + * video overlay support + * vsync synchronization + * acceleration support (8514-like 2D, busmaster transfers) + + +Known bugs +========== + + * cursor disable in text mode doesn't work + + +-- +Ondrej Zajicek <santiago@crfreenet.org> |