Adding USB SVGA

From OLPC

Revision as of 02:26, 26 October 2011 by Martinlanghoff (Talk | contribs)
(diff) ← Older revision | Current revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Using recent Operating Systems, it is easy to make a USB2VGA adapter work with your XO. Using USB2VGA adapters has some limitations (see below for details).

Contents

Selecting the right USB-SVGA adapter

Short version: The devices tested and known to work are

While in general, this feature works with USB-SVGA adapters based on the SIS Net2280/SiS315 chipset, which uses the 'sisusbvga'(kernel) and 'sisusb'(xorg) drivers, only those two models have been reported to work. Other devices from Startech.com are available, with similar model names, but you should not expect them to work.

For more details, see the author's page here. Some devices reported to work according to the NSLU2 wiki

Using lsusb, we have seen these identifiers on devices that work:

 Bus 004 Device 005: ID 0711:0900 Magic Control Technology Corp. SVGA Adapter

On XO OS 10.1.3 and newer

Just plug the USB2VGA device to the XO, and start it up (or restart it if it is on). The desktop will only appear on the external display. The LCD of the XO will not be operational.

On XO OS 10.1.1 and 10.1.2

You will need to install some required modules from the main repositories

yum install xorg-x11-drv-sisusb

And the RPM containing the required auto-configuration scripts

wget http://dev.laptop.org/~martin/public_rpms/f11/olpc-utils-1.0.31-1.fc11.i586.rpm
rpm -Uvh olpc-utils-1.0.31-1.fc11.i586.rpm

Connect the USB SVGA adapter, and restart your XO.

On XO OS 8.2.1 and earlier

The process is more complex as you will have to compile kernel and xorg modules. See Adding_USB_SVGA/Fedora_9_and_earlier

Limitations and quirks

  • No mirroring, external display only. When you are using the USB VGA device, we disable the internal LCD screen. This is for two reasons
    • Performance is bad when trying to drive the 2 screen simultaneously. This is in part because the internal display is very differentrom a conventional screen.
    • On XO-1, the OS releases based on Fedora 11 (the 10.1.x series) cannot run both the internal video card and a SiS USB device.
  • Sometimes changes are not shown on screen immediately. Move the pointer to get the external display updated. There is a bug in the SiSUSBVGA driver that "forgets" to update the screen. We are investigating.
  • When using the USB SVGA device, power saving mode is disabled so you battery will drain faster.
  • Performance is slower.
  • Some activities (for example Pippy) do not work or display correctly on the "smaller" screen.
  • There may be a visible difference in color temperature
  • Earlier than 10.1.3 the kernel module may be missing in some OS/XO model combinations -- compile the kernel and modprobe sisusbvga.

Pictures

Here are some pictures of the OLPC working with the USB-SVGA adapter.

Other Resources

Personal tools
  • Log in
  • Login with OpenID
About OLPC
About the laptop
About the tablet
Projects
OLPC wiki
Toolbox