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<!-- Title information -->
<title> Information for SiS Users
<author> Xavier Ducoin (<it>xavier@rd.lectra.fr</it>)
<date> 27 February 1998
<title>Information for SiS Users
<author>Juanjo Santamarta (<email>santamarta@ctv.es</email>)
<date>5 March 2000
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/SiS.sgml,v 3.7 2000/03/06 22:59:24 dawes Exp $
<!-- Table of contents -->
<sect> Introduction <p>
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.
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 many advanced features. These include:
The driver supports :
<item>Linear Addressing
<item>8/15/16/24 bits per pixel
<item>Fully programmable clocks are supported
<item>H/W cursor support
<item>BitBLT acceleration of many operations
<item>H/W acceleration and cursor support
<item>XAA support (XFree86 Acceleration Architecture)
<!-- this is incorrect
<sect> Supported chips <p>
<tag>SiS 86c201</tag>
(External hardware clock)
<tag>SiS 86c202, SiS 86c205</tag>
(Internal clock synthesizer)
SiS 530, SiS 86c2x5, SiS 5597/5598, SiS 6326
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 `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
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.
<tag>Option &dquot;noaccel&dquot;</tag>
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).
<tag>Option &dquot;hw_clocks&dquot;</tag>
On chips 86c202 and later, the default is to use the programmable
clock for all clocks. It is possible to use the fixed clocks
supported by the chip instead of using this option (manufacturer
<tag>Option &dquot;sw_cursor&dquot, &dquot;hw_cursor&dquot;</tag>
<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.
<tag>Option &dquot;no_linear&dquot;</tag>
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.
<tag>Option &dquot;no_bitblt&dquot;</tag>
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.
<tag>Option &dquot;no_imageblt&dquot;</tag>
It is useful for problems related to image writing, and possible
stipple acceleration problems. In general this will result in a reduced
<!-- 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
......@@ -83,35 +99,33 @@ driver you'll need to consider several points:
<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
<item>Dot Clock
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.
SiS recommended video modes for 6326:
<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
<sect> Troubleshooting <p>
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.
<!-- 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.
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.
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/SiS.sgml,v 1998/02/27 02:45:24 dawes Exp $
$Xorg: SiS.sgml,v 1.3 2000/08/17 19:51:05 cpqbld Exp $
Document based on 3.3 version written by Xavier Ducoin.
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