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<!-- Title information -->
<title>Information for SiS Users
<author>Juanjo Santamarta (<email>santamarta@ctv.es</email>)
<date>5 March 2000

<ident>
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/SiS.sgml,v 3.7 2000/03/06 22:59:24 dawes Exp $
</ident>

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<sect> Introduction <p>

This driver was primarily written for the SiS6326 and SiS530 by Alan Hourihane.
It also works on 5597/5598 chips, and probably on older SiS862X5 family.

The driver supports :
<itemize>
  <item>Linear Addressing
  <item>8/15/16/24 bits per pixel
  <item>Fully programmable clocks are supported
  <item>H/W acceleration and cursor support
  <item>XAA support (XFree86 Acceleration Architecture)
</itemize>

<!-- this is incorrect
<sect> Supported chips <p>

<quote>
SiS 530, SiS 86c2x5, SiS 5597/5598, SiS 6326
</quote>

This driver needs linear framebuffer support in the card. Because this 
SiS 86C201 and 86C202 based cards don't work with this driver.

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

<sect> XF86Config Options <p>

The following options are of particular interest for the SiS
driver. Each of them must be specified in the Device section of the
XF86Config file for this card.

<descrip>
<tag>Option "SetMclk"</tag>
        This option lets you to modify the memory clocking of your card.
    (only for 5597 and 6326) Modifying the memory timings can destroy the 
	device, but usually the only ill effects of overclocking is to 
	have some noise an drawing errors, but BE CAREFUL. Usually a little 
	increment can improve the drawing speed, and allows also higher dotclocks. 
	The server reports default memclock on starting messages, so take it
	as a base. Units are in KHZ.
<tag>Option "DacSpeed"</tag>
        This option lets you to modify the maximum allowed dotclock).	
<tag>Option "sw_cursor", "hw_cursor"</tag>
	The default is for using the hardware cursor.
<!-- Which of these chips is even supported? -->
<tag>Option "Turboqueue"</tag>
	5597/8 and 6326 have the option to extend the engine command queue on
	VRAM. With extended queue length, the driver only checks queue status 
	on some color-expansion commands. This gives some performance improvement, 
	but is possible to lose some commands, corrupting screen output. As the 
	size of extended command queue is 16-32K, the probability is very low, but
	exists. The performance gain observed is around 8-10%. Currently, using
	this option will occasionally freeze the acceleration engine, causing 
	weird image display.
<tag>Option "FastVram"</tag>
        Enables 1 cycle memory access. Try it. Increased memory bandwidth reduces
	the possibility of glitches and noise on high resolution modes. 

<tag>Option "PciRetry"</tag>

<tag>Option "NoAccel"</tag>
        Disables various hardware accelerations.

<tag>VideoRAM size</tag> The SiS chips can only directly address 4096K
        bytes of video RAM.  Some video cards using these chips are
        shipped with additional video RAM.  The videoRAM must be
        explicitly limited to 4096 for those cards.  Attempting to use
        the additional RAM leads to a variety of scrambled screen
        artifacts.

</descrip>


<sect> Modelines <p>

When constructing a modeline for use with the Sis
driver you'll need to consider several points:
<itemize>
  <item>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. Also, Turboqueue allocate 32k of Vram. 
  <item>Dot Clock. SiS documents the following video modes to work with 
        6326. The max dot clock allowable for your 6326 based board depends 
	also on the memory installed on it. Option FastVram can be needed 
	for high dot clocks to work. Of course, the memory installed must
	allow 1 cycle R/W. 
	<p>
        SiS recommended video modes for 6326: 
	<descrip>
         <tag>640x480 :</tag>4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
         <tag>800x600 :</tag>4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
         <tag>1024x768 :</tag>4, 8, 15, 16, 24 bpp at 85Hz Non-interlaced
         <tag>1280x1024 :</tag>4, 8, 15, 16, 24 bpp at 75Hz Non-interlaced
         <tag>1600x1200 :</tag>4, 8  bpp at 65Hz Non-interlaced
	</descrip>
</itemize>

<sect> Troubleshooting <p>

<!-- don't have XF86Setup for 4.0
The generic VGA driver don't work with 6326, so XF86Setup can't be used
for this card. Please use xf86config instead.
-->

Some video modes with high dot-clocks don't work at all, resulting on black 
screen. Lowering dotclock in that case could solve the problem. 

Document based on 3.3 version written by Xavier Ducoin.

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