








			   Information for SiS Users

		      Xavier Ducoin (xavier@rd.lectra.fr)

				27 February 1998



1.  Introduction

This driver was primarily written for the SiS86c201.  It also works on the 202
and the 205 chips.  Support for other SiS products is not available in XFree86
release 3.3.2.	Drivers for the 5597/8 are currently under development and
should be available in the next release.

The driver supports many advanced features.  These include:

   o Linear Addressing

   o 8/15/16/24 bits per pixel

   o Fully programmable clocks are supported

   o H/W cursor support

   o BitBLT acceleration of many operations

   o XAA support (XFree86 Acceleration Architecture)


2.  Supported chips

      SiS 86c201
	    (External hardware clock)

      SiS 86c202, SiS 86c205
	    (Internal clock synthesizer)

Color expansion is not supported by the engine in 16M-color graphic mode.


3.  XF86Config Options

The following options are of particular interest for the SiS driver. Each of
them must be specified in the `svga' driver section of the XF86Config file,
within the Screen subsections of the depths to which they are applicable (you
can enable options for all depths by specifying them in the Device section).

      Option "noaccel"
	    By default the XAA (XFree86 Acceleration Architecture) is used.
	    This option will disable the use of the XAA and will enable the old
	    BitBlt acceleration operations. (see below).


 Information for SiS Users





 Information for SiS Users



      Option "hw_clocks"
	    On chips 86c202 and later, the default is to use the programmable
	    clock for all clocks. It is possible to use the fixed clocks sup-
	    ported by the chip instead of using this option (manufacturer
	    dependent).

      Option "sw_cursor", "hw_cursor"
	    The default is for using the hardware cursor.

      Option "no_linear"
	    By default linear addressing is used on all chips.	However this
	    might be broken in some implementations. It is possible to turn the
	    linear addressing off with this option.  Note that H/W acceleration
	    and 16/24bpp are only supported with linear addressing.

      Option "no_bitblt"
	    This option will disable the use of all the BitBLT engine.	It is
	    useful for problems related to acceleration problems.  In general
	    this will result in a reduced performance.

      Option "no_imageblt"
	    It is useful for problems related to image writing, and possible
	    stipple acceleration problems. In general this will result in a
	    reduced performance.


4.  Modelines

When constructing a modeline for use with the Sis driver you'll need to con-
sider several points:

   o H/W Acceleration.	The H/W cursor, and fill operations currently allocate
     memory of the video ram for there own use.  If this is not available these
     functions will automatically be disabled.

   o Dot Clock


5.  Troubleshooting

With intensive generation there is a snow phenomenon on the screen.  Can't
remove it even if I used the fifo low/high water mark dumped from W95.

With intensive generation in 1024x768 65 Mhz sometimes some points (rubbish,
fuzz... hard to explain) appear in memory, like memory violations or memory
corruption.  It looks like an electronic refresh not well done or VClk too near
the MClk.  I use the default Mclk set by BIOS.	It is hard to reproduce this
problem (It can take one hour, two or more).  I can't reproduce this problem in
1024x768 75 MHz or 1280x1024 110 MHz or 1152x900 95 MHz.

     Generated from XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/SiS.sgml,v 3.3.2.1 1998/02/27 02:45:24 dawes Exp $











 Information for SiS Users





































































				   CONTENTS



1. Introduction  ............................................................ 1

2. Supported chips  ......................................................... 1

3. XF86Config Options  ...................................................... 1

4. Modelines  ............................................................... 2

5. Troubleshooting  ......................................................... 2











































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