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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
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Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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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>