android_kernel_xiaomi_sm8350/Documentation/fb/s3fb.txt
Ondrej Zajicek a268422de8 [PATCH] fbdev driver for S3 Trio/Virge
Add a driver for S3 Trio / S3 Virge.  Driver is tested with most versions
of S3 Trio and with S3 Virge/DX, on i386.

(akpm: We kind-of have support for this hardware already, but...

virgefb.c
  - amiga/zorro specific,
  - broken (according to Kconfig),
  - uses obsolete/nonexistent interface (struct display_switch)
  - recent Adrian Bunk's patch removes this driver

S3triofb.c
  - ppc/openfirmware specific
  - minimal functionality
  - broken (according to Kconfig),
  - uses obsolete/nonexistent interface (struct display_switch)
)

Signed-off-by: Ondrej Zajicek <santiago@crfreenet.org>
Cc: James Simmons <jsimmons@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:41 -08:00

79 lines
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s3fb - fbdev driver for S3 Trio/Virge chips
===========================================
Supported Hardware
==================
S3 Trio32
S3 Trio64 (and variants V+, UV+, V2/DX, V2/GX)
S3 Virge (and variants VX, DX, GX and GX2+)
S3 Plato/PX (completely untested)
S3 Aurora64V+ (completely untested)
- only PCI bus supported
- only BIOS initialized VGA devices supported
- probably not working on big endian
I tested s3fb on Trio64 (plain, V+ and V2/DX) and Virge (plain, VX, DX),
all on i386.
Supported Features
==================
* 4 bpp pseudocolor modes (with 18bit palette, two variants)
* 8 bpp pseudocolor mode (with 18bit palette)
* 16 bpp truecolor modes (RGB 555 and RGB 565)
* 24 bpp truecolor mode (RGB 888) on (only on Virge VX)
* 32 bpp truecolor mode (RGB 888) on (not on Virge VX)
* text mode (activated by bpp = 0)
* interlaced mode variant (not available in text mode)
* 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 between 50-60 MHz, depending on specific hardware).
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
* big endian support
* Zorro bus support
* MMIO support
* 24 bpp mode support on more cards
* support for fontwidths != 8 in 4 bpp modes
* support for fontheight != 16 in text mode
* composite and external sync (is anyone able to test this?)
* hardware cursor
* video overlay support
* vsync synchronization
* feature connector support
* acceleration support (8514-like 2D, Virge 3D, busmaster transfers)
* better values for some magic registers (performance issues)
Known bugs
==========
* cursor disable in text mode doesn't work
--
Ondrej Zajicek <santiago@crfreenet.org>