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openchrome

NAME

via - video driver for VIA Unichromes

SYNOPSIS

 Section "Device"
   Identifier "string"
   Driver "via"
   ...
 EndSection
 

DESCRIPTION

via is an Xorg driver for VIA chipsets that have an integrated Unichrome graphics engine.

The via driver supports the CLE266, KM/N400, K8M/N800, PM/N800 and CN400 chipsets from VIA, including 2D acceleration and the Xv video overlay extensions. Flat panel, TV, and VGA outputs are supported, depending on the hardware configuration.

3D direct rendering is available using experimental drivers from Mesa (www.mesa3d.org). There is also an XvMC client library for hardware acceleration of MPEG1/MPEG2 decoding (available on the CLE266, PM/N800, K8M/N800, and CN400 chipsets) that uses the Direct Rendering Infrastructure (DRI). The XvMC client library implements a non-standard "VLD" extension to the XvMC standard. The current Direct Rendering Manager (DRM) kernel module is available at dri.sourceforge.net.

The driver supports free modes for Unichrome Pros (K8M/N800, PM/N800, and CN400). For plain Unichromes (CLE266, KM/N400), it currently supports only a limited number of dotclocks, so if you are using X modelines you must make sure that the dotclock is one of those supported. Supported dotclocks on plain Unichromes are currently (in MHz): 25.2, 25.312, 26.591, 31.5, 31.704, 32.663, 33.750, 35.5, 36.0, 39.822, 40.0, 41.164, 46.981, 49.5, 50.0, 56.3, 57.284, 64.995, 65.0, 65.028, 74.480, 75.0, 78.8, 81.613, 94.5, 108.0, 108.28, 122.0, 122.726, 135.0, 148.5, 155.8, 157.5, 161.793, 162.0, 175.5, 189.0, 202.5, 204.8, 218.3, 229.5. On top of this, bandwidth restrictions apply for both Unichromes and Unichrome Pros.

CONFIGURATION DETAILS

Please refer to xorg.conf() for general configuration details. This section only covers configuration details specific to this driver.

The following driver options are supported:

Option "AccelMethod" "string"

The driver supports "XAA" and "EXA" acceleration methods. The default method is XAA, since EXA is still experimental. Contrary to XAA, EXA implements acceleration for screen uploads and downlads (if DRI is enabled) and for the Render/Composite extension.

Option "ActiveDevice" "string"

Specifies the active device combination. Any string containing "CRT", "LCD", "DFP", "TV" should be possible. "CRT" represents anything that is connected to the VGA port, "LCD" and "DFP" are for laptop panels (not TFT screens attached to the VGA port), "TV" is self-explanatory. The default is to use what is detected. The driver is currently unable to use LCD and TV simultaneously, and will favour the LCD.

Option "AGPMem" "integer"

Sets the amount of AGP memory that is allocated at X server startup. The allocated memory will be "integer" kB. This AGP memory is used for the AGP command buffer (if option "EnableAGPDMA" is set to "true"), for DRI textures, and for the EXA scratch area. The driver will allocate at least one system page of AGP memory and, if the AGP command buffer is used, at least 2MB + one system page. If there is no room for the EXA scratch area in AGP space, it will be allocated from VRAM. If there is no room for DRI textures, they will be allocated from the DRI part of VRAM (see the option "MaxDRIMem"). The default amount of AGP is 32768kB. Note that the AGP aperture set in the BIOS must be able to accomodate the amount of AGP memory specified here. Otherwise no AGP memory will be available. It is safe to set a very large AGP aperture in the BIOS.

Option "Center" "boolean"

Enables or disables image centering on DVI displays.

Option "DisableIRQ" "boolean"

Disables the Vblank IRQ. This is a workaround for some mainboards that have problems with IRQs from the Unichrome engine. With IRQs disabled, DRI clients have no way to synchronize drawing to Vblank. ( Enabled by default on the KM400 and K8M800 Chipsets )

Option "DisableVQ" "boolean"

Disables the use of VQ. VQ is enabled by default.

Option "EnableAGPDMA" "boolean"

Enables the AGP DMA functionality in DRM. This requires that DRI is enabled and will force 2D and 3D acceleration to use AGP DMA. The XvMC DRI client will also make use of this on the CLE266 to consume much less CPU. ( This is enabled by default on all chipsets except the K8M890 and P4M900 )

Option "ExaNoComposite" "boolean"

If EXA is enabled (using the option "AccelMethod"), this option enables or disables acceleration of compositing. Since EXA, and in particular its composite acceleration, is still experimental, this is a way to disable a misbehaving composite acceleration.

Option "ExaScratchSize" "integer"

Sets the size of the EXA scratch area to "integer" kB. This area is used by EXA as a last place to look for available space for pixmaps. Too little space will slow compositing down. This option should be set to the size of the largest pixmap used. If you have a screen width of over 1024 pixels and use 24 bpp, set this to 8192. Otherwise you can leave this at the default 4096. The space will be allocated from AGP memory if available, otherwise from VRAM.

Option "HWCursor" "boolean"

Enables or disables the use of hardware cursors. The default is enabled.

Option "LCDDualEdge" "boolean"

Enables or disables the use of dual-edge mode to set the LCD.

Option "MaxDRIMem" "integer"

Sets the maximum amount of VRAM memory allocated for DRI clients to "integer" kB. Normally DRI clients get half the available VRAM size, but in some cases it may make sense to limit this amount. For example, if you are using a composite manager and you want to give as much memory as possible to the EXA pixmap storage area.

Option "MigrationHeuristic" "string"

Sets the heuristic for EXA pixmap migration. This is an EXA core option, and on Xorg xserver versions after 1.1.0 this defaults to "smart". The Openchrome driver performs best with "greedy", so you should really add this option to your configuration file. The third possibility is "always", which might become more useful in the future.

Option "NoAccel" "boolean"

Disables or enables acceleration. Default: acceleration is enabled.

Option "NoAGPFor2D" "boolean"

With this option set, 2D acceleration will not use AGP DMA even if it is enabled.

Option "NoXVDMA" "boolean"

If DRI is enabled, Xv normally uses PCI DMA to transfer video images from system to frame-buffer memory. This is somewhat slower than direct copies due to the limitations of the PCI bus, but on the other hand it decreases CPU usage significantly, particularly on computers with fast processors. Some video players are buggy and will display rendering artifacts when PCI DMA is used. If you experience this, or don't want your PCI bus to be stressed with Xv images, set this option to "true". This option has no effect when DRI is not enabled.

Option "PanelSize" "string"

Specifies the size (width x height) of the LCD panel attached to the system. The sizes 640x480, 800x600, 1024x768, 1280x1024, and 1400x1050 are supported.

Option "Rotate" "string"

Rotates the display either clockwise ("CW") or counterclockwise ("CCW"). Rotation is only supported unaccelerated.

Option "ShadowFB" "boolean"

Uses a shadow frame buffer. This is required when rotating the display, but otherwise defaults to disabled.

Option "SWCursor" "boolean"

Enables or disables the use of a software cursor. The default is disabled.

Option "TVDeflicker" "integer"

Specifies the deflicker setting for TV output. Valid values are "0", "1", and "2". 0) No deflicker, 1) 1:1:1 deflicker, 2) 1:2:1 deflicker.

Option "TVDotCrawl" "boolean"

Enables or disables dotcrawl.

Option "TVOutput" "string"

Specifies which TV output to use. The driver supports "S-Video", "Composite", "SC", "RGB" and "YCbCr" outputs. Note that on some EPIA boards the compositer-video port is shared with audio-out and is selected via a jumper.

Option "TVType" "string"

Specifies TV output format. The driver currently supports "NTSC" and "PAL" timings only.

Option "VBEModes" "boolean"

Uses the VBE BIOS calls to set the display mode. This mimics the behaviour of the vesa video driver but still provides acceleration and other features. This option may be used if your hardware works with the vesa driver but not with the Openchrome driver. It may not work on 64-bit systems. Using "VBEModes" may speed up driver acceleration significantly due to a more aggressive hardware setting, particularly on systems with low memory bandwidth. Your refresh rate may be limited to 60 Hz on some systems.

Option "VBESaveRestore" "boolean"

Uses the VBE BIOS calls to save and restore the display state when the X server is launched. This can be extremely slow on some hardware, and the system may appear to have locked for 10 seconds or so. The default is to use the driver builtin function. This option only works if option "VBEModes" is enabled.

Option "VideoRAM" "integer"

Overrides the VideoRAM autodetection. This should never be needed.

TV ENCODERS

Unichromes tend to be paired with several different TV encoders.

VIA Technologies VT1621

Still untested, as no combination with a Unichrome is known or available. Supports the following normal modes: "640x480" and "800x600". Use "640x480Over" and "800x600Over" for vertical overscan. These modes are made available by the driver; modelines provided in xorg.conf will be ignored.

VIA Technologies VT1622, VT1622A, VT1623

Supports the following modes: "640x480", "800x600", "1024x768", "848x480", "720x480" (NTSC only) and "720x576" (PAL only). Use "640x480Over", "800x600Over", "1024x768Over", "848x480Over", "720x480Over" (NTSC) and "720x576Over" (PAL) for vertical overscan. The modes "720x480Noscale" (NTSC) and "720x576Noscale" (PAL) (available on VT1622 only) provide cleaner TV output (unscaled with only minimal overscan). These modes are made available by the driver; modelines provided in xorg.conf will be ignored.

SEE ALSO

Xorg(), xorg.conf(), xorgconfig(), Xserver(), X()

AUTHORS

Authors include: ...