Ubuntu Manpage: s3 - S3 video driver

Provided by: xserver-xorg-video-s3-lts-wily_0.6.5-0ubuntu5build1~trusty1_amd64

NAME

       s3 - S3 video driver

SYNOPSIS

       Section "Device"
         Identifier "devname"
         Driver "s3"
         ...
         [Option "optionname" ["optionvalue"]]
       EndSection

SUPPORTED HARDWARE

       The s3 driver supports PCI video cards based on the following S3 chips:

       Trio32      86C732

       Trio64      86C764

       Trio64V+    86C765

       Aurora64V+  86CM65

       Trio64UV+   86C767

       Trio64V2/DX 86C775

       Trio64V2/GX 86C785

       Vision964   86C964

       Vision968   86C968

       Also driver supports the following RAMDACs:

       IBM 524, IBM 524A, IBM 526, IBM 526DB

       TI ViewPoint 3025

DESCRIPTION

       s3  is  an  Xorg  driver  for  S3  based video cards. The driver provides full accelerated
       support for the following colour depths: 8, 15, 16 and  24.  The  overlay  video  (Xv)  is
       supported  in  depths  16  and 24 for the Trio64V+, Trio64UV+, Trio64V2/DX and Trio64V2/GX
       chips.

CONFIGURATION DETAILS

Please refer to xorg.conf(5) for general configuration details. This section only covers
configuration details specific to this driver. All options names are case and white space
insensitive when parsed by the server, for example, "trio 32/64" and "Trio32/64" are
equivalent.

Chip overriding
The driver auto-detects the chipset and RAMDAC, but the following Chipset names may
optionally be specified in the configuration file "Device" section, and will override the
auto-detection:

"964-0", "964-1" 86C964 (rev.0 and rev.1)

"968" 86C968

"Trio32/64" 86C732/86C764

"Aurora64V+" 86CM65

"Trio64UV+" 86C767

"Trio64V2/DX/GX" 86C775/86C785

The 86C765 (Trio64V+) is Chipset "Trio32/64" with ChipRev greater or equal 0x40.

An overriding of RAMDAC auto-detection currently is not implemented.

Colour depth
For every supported colour depth the X server automatically selects an appropriate number
of bits per pixel (bpp) for framebuffer. The depth 8 is represented by 8 bpp framebuffer
(1 byte/pixel), the depths 15 and 16 (respectively 5.5.5 and 5.6.5 pixel formats) are
represented by the 16 bpp framebuffer (2 bytes/pixel). Whenever the depth 24 is
configured, the X server by default uses the 32 bpp framebuffer (4 bytes/pixel), and the
hardware is adjusted accordingly to the X.8.8.8 pixel format, where X is the ignored upper
byte.

As the second option for the depth 24, the X server can be configured to use 24 bpp
framebuffer with the 8.8.8 pixel format (3 bytes/pixel), which is supported by Trio64V+,
Trio64UV+, Trio64V2/DX and Trio64V2/GX. If the video board has limited video RAM the 24
bpp framebuffer has an advantage over 32 bpp framebuffer as it requires less memory to
store screen, and, therefore, more space will be available for a video frame (see "Overlay
video" section). The 24 bpp framebuffer can be selected by X server's option -fbbpp 24 or
by specifying DefaultFbBpp option in xorg.conf(5):

Section "Screen"
DefaultFbBpp 24
DefaultDepth 24
...
EndSection

However, the 24 bpp framebuffer mode has the hardware limitations: (i) the 2D acceleration
doesn't work with this mode (use the "shadowFB" option to speed up drawing routines in
this case); (ii) 24 bpp framebuffer cannot be used with either interlaced or doublescan
graphics modes.

Overlay video
If your video board has limited RAM it would be useful to estimate how large video frame
might be placed in offscreen video memory. Suppose that the video board has 2 MB of RAM,
and X server is configured to display 800x600 with the depth 24. By default the 32 bpp
framebuffer will be chosen for this depth, so 800 x 600 x 4 = 1875 kB will be reserved for
screen, and 2 MB - 1875 kB = 173 kB will remain for the offscreen area. This is sufficient
space, for example, for the VCD NTSC 352x240 frame. If you need to upscale video with a
bigger frame, but it doesn't fit the offscreen area, the only way to do this is to lower
either the resolution or framebuffer's depth or both before the viewing, otherwise, you
will get the allocation error and will not see the video. For example, with 24 bpp
framebuffer and the same resolution 800x600 the offscreen area will be about 640 kB - it's
enough for the 640x480 frame. 800x600 with the 16 bpp framebuffer gives about 1110 kB of
offscreen area - this allows to upscale up to 768x576 movies. Note, that all movie
resolutions in examples above are provided as a reference; the movies can have the
different aspect ratios and non-standard dimensions. A total pixel amount is the main
consideration not the certain width and height.

Due to hardware limitation the overlay video will not work with the interlaced/doublescan
modes. Downscaling is not implemented in hardware.

Configuration options
The following display Options are supported:

Option "HWCursor" "boolean"
Enable or disable the hardware cursor. Currently, hardware cursor is not
implemented, so the option will be ignored. Default: off (software cursor).

Option "NoAccel" "boolean"
Disable acceleration. Very useful for determining if the driver has problems with
drawing and acceleration routines. This is the first option to try if your server
runs but you see graphic corruption on the screen. Using it decreases performance,
as it uses software emulation for drawing operations the video driver can
accelerate with hardware. Default: off (acceleration is enabled).

Option "ShadowFB" "boolean"
Use shadow framebuffer. Disables hardware acceleration. Use this option when the
hardware acceleration is not available or undesirable. Default: off.

Option "XVideo" "boolean"
Enable or disable Xv support. Default: on.

The following video memory Options are supported:

Option "slow_dram_refresh" "boolean"
Enable three refresh cycles per scanline. Default: off (one refresh cycle).

Option "slow_edodram" "boolean"
Switch to 2-cycle EDO mode. Try this if you encounter pixel corruption. Using this
option will cause a decrease in performance. Default: off (BIOS defaults).

Option "slow_dram" "boolean"
For Trio and Aurora64V+ chips: increase -RAS Precharge Timing to 3.5 MCLK. Try this
option if you encounter pixel errors. Default: off (BIOS defaults).

Option "slow_vram" "boolean"
For Vision964, Vision968 chips: increase -RAS Low Timing to 4.5 MCLK. Default: off
(BIOS defaults).

AUTHORS