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Kendor
Asked: 2011-01-23 08:01:25 +0800 CST

Looking for USB VGA Adapter that works for sure?

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I can't seem to get a straight answer on this. I would like to add a 3rd display onto my laptop + external monitor setup. While my current setup (Thinkpad X201) has an open VGA port (am using the laptop's display + displayport with external monitor) it appears that I can't drive 3 monitors natively.

I would like to explore what my alternatives are to get another display into the mix. I've found lots of references to displaylink but nothing absolutely confirmed to work.

10.10

1 Answers

  1. A user reports it working on Ubuntu 9.04 after compiling some packages: http://mulchman.org/blog/?tag=displaylink

    edit: apt-cache search displaylink returns xserver-xorg-video-displaylink - X driver for DisplayLink devices...it wouldn't be included if it didn't work. It might not support ALL resolutions, but I think it more than satisfies will it work.

    edit: I would try pasting this section into you xorg configuration:

    Section "Device"
    Identifier "DisplayLinkDevice"
    driver "displaylink"
    Option "fbdev" "/dev/fb1"
    EndSection

    Section "Monitor"
    Identifier "DisplayLinkMonitor"
    EndSection

    Section "Screen"
    Identifier "DisplayLinkScreen"
    Device "DisplayLinkDevice"
    Monitor "DisplayLinkMonitor"
    SubSection "Display"
    Depth 16
    Modes "1280x1024"
    EndSubSection
    EndSection

    Even with the windows drivers not all resolutions are supported across all chipsets.

    another point worth noting is that in some configurations it has been noted that the DVI dongle doesn't function appropriately

    okay maybe i found it: http://lists.freedesktop.org/archives/libdlo/2010-November/000807.html


    The most interesting thing is that I found out why I can use the
    displaylink driver together with nvidia but not the fbdev driver.

    This is just an explicit check (xf86Bus.c, xf86PostProbe()) whether both
    framebuffer and pci devices have been claimed, if so the server refuses
    to start.
    The displaylink driver just clears the corresponding fbSlotClaimed flag,
    no more magic required. But, there is another (similar) check in
    xf86ClaimFbSlot() (xf86fbBus.c) that, when claiming a frambuffer slot,
    makes sure no PCI slot has been allocated, I guess thats the reason why
    the displaylink driven device must be registered first (as primary screen).

    On another thread the green screen problem is attributed to using DirectFB

    discussion here: http://web.archiveorange.com/archive/v/BNQl8iH957oQe619QVek
    they indicate that it worked, if slowly. but the box in question was a 266MHz monster so...

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