Table of Contents
openchrome - video driver for VIA Unichromes
Section Device
Identifier string
Driver openchrome
...
EndSection
openchrome is an Xorg driver for VIA chipsets that
have an integrated Unichrome graphics engine.
The openchrome 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.
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.
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.
Xorg(), xorg.conf(), xorgconfig(),
Xserver(), X()
Authors include: ...
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