vt8623fb: new framebuffer driver for VIA VT8623

This patch adds fbdev driver for graphics core in VIA VT8623

[adaplas@gmail.com: build fixes]
Signed-off-by: Ondrej Zajicek <santiago@crfreenet.org>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/Documentation/fb/vt8623fb.txt b/Documentation/fb/vt8623fb.txt
new file mode 100644
index 000000000000..f654576c56b7
--- /dev/null
+++ b/Documentation/fb/vt8623fb.txt
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+
+        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>