3 XF86Config Options

Contents of this section

The following options are of particular interest to the Chips and Technologies ct655xx 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 section).

Option "noaccel"

This option will disable the use of any accelerated functions. This is likely to help with some problems related to DRAM timing, high dot clocks, and bugs in accelerated functions, at the cost of performance (which will still be reasonable on VLB/PCI).

Option "no_bitblt" (Chips 65545 and later)

This option will disable the use of the BitBLT engine which the 65545 and above have. If you can use the "noaccel" option to correct a problem, then this option might be better to use. It still allows the use of generic speedups.

Option "no_imageblt" (Chips 65545 and later)

This option will have the effect of disabling the use of BitBLT functions that go from system memory to video memory. It is useful for problems related to image writes, and possible acceleration problems. In general this will result in a reduced performance.

videoram 1024 (or another value)

This option will override the detected amount of video memory, and pretend the given amount of memory is present on the card. Note that many ct655xx chips only allow up to 1Mb of videoram, and the amount should be correctly detected.

Option "nolinear" (Chips 65530 and later)

By default linear addressing is used on all ct655xx 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.

MemBase 0x03b00000 (or a different address)

This sets the physical memory base address of the linear framebuffer. Typically this is probed correctly, but if you believe it to be mis-probed, this option might help.

Option "sw_cursor" (Chips 65545 and later)

This disables use of the hardware cursor provided by the chip. Try this if the cursor seems to have problems.

Option "STN"

The server is unable to differentiate between SS STN and TFT displays. This forces it to identify the display as a SS STN rather than a TFT.

Option "ext_fram_buf" (DSTN machines only)

In case the chipset uses a separate framebuffer (one that is not part of the vram) this option makes all of the vram available to video memory.

Option "use_modeline"

The flat panel timings are related to the panel size and not the size of the mode specified in XF86Config. For this reason the default behaviour of the server is to use the panel timings already installed in the chip. The user can force the panel timings to be recalculated from the modeline with this option. However the panel size will still be probed.

Option "fix_panel_size"

For some machines the LCD panel size is incorrectly probed from the registers. This option forces the LCD panel size to be overridden by the modeline display sizes. This will prevent the use of a mode that is a different size than the panel. Before using this check that the server reports an incorrect panel size. This option can be used in conjunction with the option "use_modeline" to program all the panel timings using the modeline values.

Option "no_stretch"

When the size of the mode used is less than the panel size, the default behaviour of the server is to stretch the mode in an attempt to fill the screen. A "letterbox" effect with no stretching can be achieved using this option.

Option "lcd_center"

When the size of the mode used is less than the panel size, the default behaviour of the server is to align the left hand edge of the display with the left hand edge of the screen. Using this option the mode can be centered in the screen. This option is reported to have problems with some machines at 16/24bpp, the effect of which is that the right-hand edge of the mode will be pushed off the screen.

Option "hw_clocks" (Chips 65540 and later)

On chips 65540 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 by using this option. Typically this will give you some or all of the clocks 25.175, 28.322, 31.000 and 36.000MHz. Note that many flat panels will need a dot clock that is lower than 25.175MHz to synchronise. The programmable clock makes this option obsolete and so it's use isn't recommended.

TextClockFreq 25.175

It is impossible for the server to read the value of the currently used frequency for the text console from the chip with the ct6554x series of chips. Therefore the server uses a default value of 25.175MHz as the text console clock. For some LCDs, in particular DSTN screens, this clock will be wrong. This allows the user to select a different clock for the server to use when returning to the text console.

Option "mmio"

This enables the use of memory-mapped I/O to talk to the BitBLT engine. By default memory-mapped I/O is not enabled on the 6554x series of chips, and is only usable on 6554x's with PCI buses. It also enables additional acceleration using memory-mapped I/O. This option has no effect when not using the BitBLT engine (e.g. when using "no_bitblt"), or for the 65550 which can only use MMIO for access to the BitBLT engine.

Option "suspend_hack"

This option sets the centering and stretching to the bios default values. This can fix suspend/resume problems on some machines. It overrides the options "lcd_center" and "no_stretch".

Option "use_18bit_bus" (Chips 65540/45/46/48)

For 24bpp on TFT screens, the server assumes that a 24bit bus is being used. This can result in a reddish tint to 24bpp mode. This option, selects an 18 bit TFT bus. For other depths this option has no effect.

Chipset "ct65546" (or some other chip)

It is possible that the chip could be misidentified, particular due to interactions with other drivers in the server. It is possible to force the server to identify a particular chip with this option. Some later releases of the ct65545, in particular the ct65545A1 and ct65545B1, are believed to have limitations very similar to those of the 65546. The server is currently configured to use the 65545 bandwidth, etc for these chips. So the user might wish to force the server to identify their chip as a ct65546 and so have a larger maximum bandwidth. Note that this forces the server to exceed the documented limitations of the chip, so take care.

Option "sync_on_green" (Chips 65550/54)

Composite sync on green. Possibly useful if you wish to use an old workstation monitor. The 65550/54 internal RAMDAC's support this mode of operation, but whether a particular machine does depends on the manufacturer.

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