Thursday, September 29, 2011

DisplayLink and vgaswitcheroo.

DisplayLink: Just something I wanted to share. The problem with current 'modern' laptops can be, that they don't provide a VGA port, which is often required to connect beamers (the reason why I needed one of those adapters). One way to to solve this, is to use some DisplayLink adapter, which allows to connect display via USB.

But it is hard to find real DisplayLink adapters, it took me two random and one informed transaction to get a supported adapter:LogiLink USB to DVI/VGA/HDMI Multi-Display Adapter (UA0077).

This adapter has quite good support in Fedora after installing the xorg-x11-driver-displaylink package.
$ sudo yum install xorg-x11-driver-displaylink
$ sudo modprobe sisusbvga
Use dmesg to find out about the assigned framebuffer-device (fb). Now the driver is available and the appropriate kernel module loaded but you still need to dump the following file into /etc/X11/xorg.conf.d/
# /etc/X11/xorg.conf.d/displaylink.conf
Section "Device"
        Option       "fbdev"     "/dev/fb2"    # use the device given in dmesg
	Identifier   "DLCard"
	Driver       "displaylink"

vgaswitcheroo: Well, I didn't find out much more on the vgaswitcheroo side. I didn't find a way to determin if a monitor is connected to the discrete card, when this card is turned of (it seems that on some setups the integrated card get's "infos" about monitors connected to the discrete card, but not on mine). But I wont continue to poll for a monitor on the discrete card, so I'll just provide some trayicon (or how i's called in the shell slang), which enables the user to switch between the cards.

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