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[Driver options] * [FAQ] * [Changelog] * [Download]

Net2280/SiS315 based USB2VGA dongles and Linux/X.org/XFree86

• Introduction
• Detailed Information
  1. The Linux kernel driver
  2. The X.org/XFree86 driver
  3. The SiS Display Control Panel ("sisctrl")
  4. Driver options and parameters
• Troubleshooting and FAQ
• Changelog
• Download and installation instructions
• How to contact the author

This page provides information on Net2280/SiS315 based USB2VGA dongles of various makes, usually called "USB2VGA" or "USB-to-SVGA dongle"; one of the companies marketing such a device is called "Sitecom", another is "Tritton". "What?!" you ask. Well, your surprised face is understandable. While NVidia and ATI (trademarks blah blah) bet on PCI express and other high-speed techniques, a company named MCT came up with something that might seem a bit anachronistical: A graphics "card" connected via USB.

But anyway, let's not become philosophical. Basically, I here provide a pair of drivers for such devices. The package consists of a Linux kernel driver that takes care of device initialisation and communication from/to the device and including a text console, and a X driver.

To make a long story short: Download it from the download section, install it as described in the installation instructions and simply place Driver "sisusb" in the Device section of /etc/X11/XF86Config or /etc/X11/XF86Config-4 or /etc/X11/xorg.conf. Simple example configuration files are in the download section.

The X driver is optionally accompanied by a display management tool called sisctrl that lets you tune the display without the need to restart the X server. This tool is available on my main page.

Preface: Since 17 Aug 2005, the driver's name is "sisusbvga". Previously it was called "sisusb".

Linux 2.6.12 and 2.6.13 already contain an older version of this driver, so if you don't need a text console there's no need for any further installation efforts (except, of course, that it must be compiled into the kernel, preferably as a module). Only users of older versions of Linux 2.6 need to install this driver separately. Update: Although 2.6.12 does contain the driver, it does not compile due to a missing Makefile. Argh.... 2.6.13 is ok.

This kernel driver takes care of device initialisation and communication with userland applications such as the X server. It is distributed in source form only and it is supposed to run on every platform Linux runs on. However, since the device only works on a USB 2.0 compliant host controller, the number of platforms is limited. Support for big-endian machines (like ARM and PPC) is implemented but as of this writing entirely untested.

The driver is - surprisingly - called sisusbvga. It utilizes the USB subsystem of the Linux kernel. It requires the EHCI driver, because, as said, the hardware device only works with USB 2.0 controllers.

I strongly recommend installing hotplug and udev in case you haven't done that yet. There are packages for these two tools in every somewhat current Linux distribution I know of. No special set up is required for the sisusb kernel driver.

In case you don't use hotplug and udev, as a prerequisity, device nodes must be created. Log in as root, and enter this in the console:

   mknod /dev/sisusbvga0 c 180 133
   mknod /dev/sisusbvga1 c 180 134
   mknod /dev/sisusbvga2 c 180 135
   mknod /dev/sisusbvga3 c 180 136
   mknod /dev/sisusbvga4 c 180 137
   mknod /dev/sisusbvga5 c 180 138
   mknod /dev/sisusbvga6 c 180 139
   mknod /dev/sisusbvga7 c 180 140
   chmod 660 /dev/sisusbvga*

Linux 2.4 is not supported and I have no plans to do that. However, some brave man hacked the driver to work with 2.4, see here.

Text consoles

Since 17 Aug 2005, the driver contains support for text consoles, like the usual VGA text console. This driver will also be in Linux 2.6.14.

By default, this feature is disabled. If you want the sisusbvga driver to take over one or more virtual terminals (ie consoles), you need to give it two parameters, named first and last. Both can be in the range from 1 to usually 16 (or whatever your kernel uses as the maximum number of consoles [MAX_NR_CONSOLES].) first defines the number of the first console to take over, last is the number of the last to take over. Counting starts at 1.

If the driver is compiled as a module, it's most convenient to use the modutils package to hand these parameters over to the driver. On my Debian system, I simply created a file named "sisusbvga" in /etc/modprobe.d/ containing the line

   options sisusbvga first=4 last=5

As soon as hotplug or anybody else modprobes the module, these parameters are handed to the driver. In my example, the driver takes over vt4 and vt5 (where, again, counting starts at 1).

If the driver is compiled into the kernel, you need to specify the parameters through the kernel commend line. lilo uses the append keyword for this in lilo.conf. For example:

   append="sisusbvga.first=4 sisusbvga.last=5"

Important, for users of Linux kernel older than 2.6.14: The driver needs the VGA8x16 font to operate. This must be enabled in your kernel configuration (CONFIG_FONT_8x16=y). However, if you don't compile in the vga text console (CONFIG_VGA_CONSOLE), this font will not be included - and initialisation of the driver will fail. Hence, even if you are running some embedded system without VGA hardware, select to compile the VGA console in order to include the required font. Another alternative was to patch the Kconfig file in drivers/video/console as follows:

Around line 138, change

config FONT_8x16
   bool "VGA 8x16 font" if FONTS
   depends on FRAMEBUFFER_CONSOLE || SGI_NEWPORT_CONSOLE=y
   default y if !SPARC32 && !SPARC64 && !FONTS
   help
      ...


to

config FONT_8x16
   bool "VGA 8x16 font" if FONTS
   default y if !FONTS
   help
      ...


This all works automatically as of kernel 2.6.14.

There is, basically, not much to be said about the sisusb X driver. It's name is "sisusb". Naturally, it has far less features than the "normal" sis driver for PCI/AGP/PCIe cards.

Monitor configuration: The driver does not support DDC. Hence, you need to set up the Monitor section according to your monitor's specifications, ie give proper HorizSync and VertRefresh ranges. See the example XF86Config file in the download section below for an example.

Xv: The SiS chip is basically supposed to support Xv (hardware video acceleration; using an overlay) but it seems that the manufacterers use a customized stripped-down version that does not support Xv. However, Xv support is implemented in the driver, but permanently disabled. If you are crazy enough to play video on the device, please use the XShm/X11 output method of your video player application.

Apart from monitor setup, no further configuration effort other than specifying Driver "sisusb" in the Device section is required for standard operation.

Multiple dongles: However, if you want to connect more than one of these devices to your box, there is something more to do: The driver uses the BusID tag in the Device section for hardware device identification. If you have only one USB2VGA dongle, you don't need to care: You don't need to set the BusID at all then. If you have two or more such devices and want them to be used in a certain order, specify the device node names in the BusID string, such as BusID "USB:/dev/mydevicename" where the parameter following the "USB:" substring is the complete name (including the path) of the device node. Alternatively, you can specify an integer number which will be prepended by "sisusbvga" which is the default device node name (if no udev rule exists).

Using this driver in combination with another video card: The sisusb X driver is not dual-head capable on XFree86 4.3 and X.org 6.7.0. This is due to a bug in these old versions of XFree86/X.org and means that the driver cannot even be used in combination with another driver at the same time. Later versions of XFree86/X.org than the ones named have no such restrictions.

Display modes and color depths: The driver has a number of default built-in modes up to 1280x1024. Although it is possible to add more modes (with higher resolutions) using Modelines and to use all modes at 24bpp color depth, this is not recommended. USB, although surprisingly fast, has its speed limit. I use the driver with 1024x768 at 16bpp and this is usable. Higher resolutions, large virtual screens and/or higher color depths severely decrease performance.

The sisusb X driver supports the interface used by SiSCtrl. Please see here for more information.

For the X driver, the following driver options are to be placed in the Device section of your configuration file (such as /etc/X11/XF86Config or /etc/X11/XF86Config-4; if both these files exist, the X server will use the -4 variant. For X.org, this file is named /etc/X11/xorg.conf).

Options marked with a * are changable during runtime using sisctrl.

For boolean options, true, on and yes have same meaning; the opposite is false, off and no. Which one of these words you use is entirely up to you. My examples use the (IMHO) most intuitive one.

X driver:
1. General options
	DisconnectTimeout	Select what to do if the device is disconnected
	CRT1Gamma*	enable/disable/set gamma correction
	NewGammaBrightness* NewGammaContrast*	define default gamma brightness/contrast
	EnableSiSCtrl	enable/disable SiSCtrl interface
2. Hardware cursor related options
	UseColorHWCursor	enable/disable color hardware cursor support

In this section I will compile some questions (including their answers) which use to come up from people out there using the driver. However, this FAQ is empty yet.

I frequently update this page whenever I have time, so the information is more actual the farther down. And please: Before reporting bugs, always try the most current version of the drivers and read this page.

UPDATE (05/01/18) Initial version of the drivers published.

UPDATE (05/01/19) Update for kernel driver. Some minor internal changes in order to make the driver fit for inclusion in the mainline kernel.

INFO (05/01/20) The kernel driver has been accepted for inclusion in the mainline Linux tree. Today's version will probably show up in 2.6.12.

UPDATE (05/01/21) Update for both drivers. Minor changes (disconnection delay now is actually seconds, screen cleared upon exit, etc). Tried to make both drivers fit for big-endian machines (for example PPC), but could not test any of the code.

UPDATE (05/01/25) X driver: Disable Xv overlay. This definitely doesn't work. Kernel driver: Fix a big-endian bug.

UPDATE (05/01/27) X driver: Make screen changes faster by not updating during every call of the block handler but only every third.

UPDATE (05/01/27) X driver: Added 1280x1024 and 1152x864 as default (built-in) modes. Make HWCursor uploading faster in double scan modes. Remove unneeded stuff.

UPDATE (05/03/30) Kernel driver: In the meantime, the driver has been integrated into the mainline kernel - it is in the 2.6.12 release candidates and will be in later versions. / Added another USB device ID (Thanks to J.W.H.).

(05/03/30) X driver: I know that the header files are accidently missing from the X driver source. I will fix this soon. At the moment, a new version is in the works that will take another few days to be finished. Please be patient.

UPDATE (05/04/05) X driver: Rewrote SiSCtrl interface. The X driver now has the same SISCTRL extension as the SiS X driver, please see the change log for the SiS driver for more information. / Fixed my scripts to include the header files in the source archive.

UPDATE (05/04/19) Kernel driver: Added another device ID, this time for "Sitecom CN-105" (Thanks to H.D.).

UPDATE (05/06/21) X driver: Work-around a signal 11 (segfault) that occured upon "X -configure".

UPDATE (05/07/09) X driver: Sync some stuff with current sis driver and current SiSCtrl.

UPDATE (05/08/17) X driver: Make X driver work with text consoles. Kernel driver: Add support for text consoles. Addendum: I removed the kernel driver because I found a serious bug... it will be updated asap.

UPDATE (05/08/23) Kernel driver: Added support for text consoles. This will require some further testing before I can commit this to the kernel folks.

UPDATE (05/08/25) Kernel driver: Fix a "scheduling while atomic" error if taking over console no 1 during boot. This is somewhat problematic but it works... Addendum: Fixed a race condition during disconnection (Revision 2).

UPDATE (05/08/29) Kernel driver: Added complete kernel patch for 2.6.13 in the download section.

UPDATE (05/09/16) X driver: The option "GammaBrightness" is now deprecated, it's replacement is "NewGammaBrightness" which uses a new better calculation algorithm. Also, option "NewGammaContrast" allows adjusting the display contrast. For more info, see here. Fixed SISCTRL extension.

Before downloading these free drivers, please consider this:

I have spent far over 4000 hours in developing all these drivers, including the SiS/XGI drivers available on this site, since 2001, not counting the numberless hours I spent answering mails and forum postings. Neither SiS, nor XGI nor any other involved company ever supported me in any way. I am - as opposed to nearly all other X.org or Linux kernel developers - not paid by anyone for doing what I did.

If you or your company wants to support development of these drivers, please feel free to sponsor. For companies, I consider a one-time financial contribution in the amount of EUR 100 / US-$ 120 within a reasonable scale. For private usage, there are no minumum exspectations from my side. Please transfer your contribution to

• either my bank account at BANK AUSTRIA CREDITANSTALT AG, account holder: Thomas Winischhofer, IBAN AT181200000706360542 (account number 706360542, SWIFT/BIC code BKAUATWW, Bankleitzahl 12000), or
• my PayPal (https://www.paypal.com) account: e-mail: thomas@winischhofer.net, type "Service", currency: EC countries EUR, outside of EC US-$. If decide to use PayPal, please transfer the amount you would like to contribute plus EUR 2,-- / US-$ 2 (which PayPal will keep as fee).

Thank you.

For newbies: What you probably want is a binary (=precompiled) X.org/XFree86 driver. The "source" of the driver is only required if your system does not work with one of the binary ones (or, of course, if you want to compile X.org/XFree86 for yourself; but then again, if you intend to do this, you're certainly no newbie...)

In this section you find the download link for the source code of the sisusb X driver. You only need this if the binaries above - for what reason ever - don't work for you or if you don't trust them (yes, I have heard that). Please read the installation instructions below for information on what to do with this. This source is for all versions of XFree86 since 4.3 and X.org as of 6.8.0. It might compile with X.org 6.7.0, but won't work with older versions of XFree86.

• X driver source (2005/09/16)

Installation:

• Note 1: The following instructions assume that you have installed binary XFree86/X.org packages and only want to (re)compile sisusb-related code and not the whole XFree86/X.org environment.
• Note 2: You need the whole XFree86 or X.org source tree to build the sisusb XFree86/X.org driver.
• Extract my source archive to a temporary directory, ie. anywhere but the XFree86/X.org source tree. Ignore an eventual "ignoring trailing garbage" message during extraction.
• In case this is the first time you install the driver, create a directory named "sisusb" under xc/programs/Xserver/hw/xfree86/drivers/
• Copy all .c and .h files from the temporary directory where you extracted the downloaded driver archive to to that newly created one in the XFree86/X.org source tree (xc/programs/Xserver/hw/xfree86/drivers/sisusb/).
• Copy the Imakefile matching your version of XFree86/X.org to that directory as well and rename it to "Imakefile".
• At the first installation, open xc/config/cf/linux.cf in a text editor, search for "XF86OSCardDrivers" and add "sisusb" to the list (which should originally consist of "v4l" and "fbdev"). The line should then read #define XF86OSCardDrivers fbdev v4l sisusb
• If you use the XFree86/X.org source from XFree.org/X.org: cd into the "xc" directory of the XFree86/X.org source tree and run "make World". At first, this will create Makefiles, convert font files and do some other stuff. Then it will start compiling. If you only want to compile the sisusb X driver and not the whole XFree86/X.org environment, you can cancel the build process as soon as there is a "Makefile" in the sisusb driver directory (where you copied the files one step before).
• Debian source: cd into the directory where the Debian source code is located (where you see a "debian" and a "build-tree" directory) and run "debian/rules build". At first, this will create Makefiles, convert font files and do some other stuff. Then it will start compiling. If you only want to compile the sisusb X driver and not the whole X environment, you can cancel the build process as soon as there is a "Makefile" in the sisusb driver directory (xc/programs/Xserver/hw/xfree86/drivers/sisusb/).
• cd into the sisusb directory (xc/programs/Xserver/hw/xfree86/drivers/sisusb/), run "make clean" and then "make".
• Copy the newly generated sisusb_drv.o to /usr/X11R6/lib/modules/drivers/
• To install the sisusb manpage, gzip the file sisusb._man, rename the gzipped file to sisusb.4.gz and copy this file to /usr/X11R6/man/man4/. (This path and filename may vary depending on your distribution.)

Please see here for more information.

• example XF86Config-4 (for simple, default configuration; please read!)

In case the internet and google can't help you, please observe the following guidelines before contacting me in person:

• Try the most recent drivers.
• Read this page from top to bottom.
• Attach the syslog from when the device was connected (and eventually, when disconnected).
• Attach the entire XFree86/X.org log (not just the screen output) and tell me in detail what your problem is; "it does not work" is not sufficient.

Finally, please don't take me as arrogant but I am tired of explaining the same matter for the Nth time just because folks can't read. Therefore, I will ignore emails that do not follow the guidelines above - with one exception: I really appreciate e-mails telling me that the driver works, too (which also gives me some sort of overview on how many people actually use it).

To contact me, send your mail to thomas@winischhoferXXX.net (but leave that "XXX" out of the address, this is just for fooling spam robots).