DisplayLink USB adapter - can only seem to use it with mplayer

[don999]

Hi all,

Just fiddling with a displaylink usb adapter, and knoppix 7.2 detects it fine, and comes up with a green display on the monitor (which is good). However, I can't seem to get it to work as an extra monitor under xorg. If I specify it all by itself in an xorg.conf file, I can get xorg to come up on that monitor. Trying to add it as another screen with any other video card in xorg.conf seems to ignore it completely.

Section "Monitor"
    Identifier   "DisplayLinkMonitor"
EndSection

Section "Device"
    Identifier "DisplayLinkDevice"
    Driver        "fbdev"
    BusID         "USB"
    Option        "fbdev" "/dev/fb2"
EndSection


Section "Screen"
      Identifier "Screen0"
    Device "DisplayLinkDevice"
    Monitor "DisplayLinkMonitor"
    DefaultDepth 16
EndSection

Oh well, I guess I'll have to be content with playing videos on it with mplayer like so:

mplayer somefile.mp4  -vo fbdev:/dev/fb2 
mplayer somefile.mp4  -vo fbdev:/dev/fb2 -zoom -x 1024 -y 768
mplayer somefile.mp4  -vo fbdev2:/dev/fb2

[klaus2008]

Trying to add it as another screen with any other video card in xorg.conf seems to ignore it completely.

Some people (e. g. https://wiki.archlinux.org/index.php/DisplayLink ) write

The DisplayLink device is normally only usable if it is set as screen0 and the internal display as screen1.

Did you try this?

[don999]

Some people (e. g. https://wiki.archlinux.org/index.php/DisplayLink ) write Did you try this?

Hi Klaus

(is this the *real* Klaus Knopper?)

Yes I tried it just about every way I could think of and still got wacky results. I think I'm going to go a bit insane if I don't take a break. The only way to get it to work is to specify it as the only device. Interesting how fbdev seems to ignore the BusID totally.

I even got this error at some point:
Cannot start in framebuffer mode. Please specify busIDs for all framebuffer devices


I could get fbdev to run with /dev/fb1 (my geforce 7300 pci-e), with /dev/fb0 (geforce mx420 pci) and /dev/fb2 (displaylink) but only with a single device. Trying to specify multiple fbdev devices with multiple xorg fbdev device sections seems to get ignored.

I'm actually typing this with X running on the displaylink and it runs awesome, with youtube running smoothly with the adobe flash plugin to iceweasel. I just wish I could get it run with my other video cards and not mutually exclusive.

I know that at some point in the future, all of this will work smoothly together, but it's so frustrating to see all of the pieces available, but unable to put them all together and integrated at once. Sooooo close... But I'm patient...

Don

[don999]

some more things to fiddle with /dev/fb devices. I thought I'd try to get an SDL application running in an fbcon like dosbox.

From a vt text console (CTRL+ALT+F2) type

export SDL_VIDEODRIVER=fbcon
export SDL_FBDEV=/dev/fb0
export DOSBOX_SDL_USESCANCODES=false              (i needed this or i couldn't type properly in dosbox)
dosbox

with any luck dosbox should open on your /dev/fb0 device. Typing "exit" drops you out of dosbox.
I can get back to my x session with CTRL+ALT+F5 but can't seem to get the input focus back to whatever console screen the dosbox is on. but CTRL+C on the text console (CTRL+ALT+F2) screen kills dosbox.

for me: geforce 7300 is /dev/fb0 geforce mx420 is /dev/fb1 and displaylink usb is /dev/fb2

weirdly export SDL_FBDEV=/dev/fb2 to run it on the displaylink makes the dosbox display corrupted (but I'm running with X on the displaylink so maybe that's why)

still kind of fun to see it work.

Don

[don999]

Interestingly, you can start up a second X session by typing this into an LXTerminal from my normal x session:

sudo xinit -- :1 -sharevts -novtswitch vt8 -config /home/knoppix/WORKING_UDLFB_XORG.CONF

(I know that running X as root isn't a good idea but I just wanted to see if it would work)

and an X window opens up on the displaylink and I can mouse over to it and type commands in the xterm.

so if I put the focus on the xterm on the displaylink and type "dosbox" and enter, dosbox runs on the displaylink. Pretty cool.

Now to figure out how to run this as an ordinary user because without sudo it complains that it doesn't have permission to open vt8 or the /var/log/Xorg1.log logfile.

Section "ServerLayout"
    Identifier     "X.org Configured"
      Option           "Xinerama" "on"
        Option           "Clone"      "off"
    Screen      0  "Screen0" 0 0

    InputDevice    "Mouse0" "CorePointer"
    InputDevice    "Keyboard0" "CoreKeyboard"
        Option            "AllowEmptyInput" "off"
EndSection

Section "Files"
    ModulePath   "/usr/lib/xorg/modules"
    FontPath     "/usr/share/fonts/X11/misc"
    FontPath     "/usr/share/fonts/X11/cyrillic"
    FontPath     "/usr/share/fonts/X11/100dpi/:unscaled"
    FontPath     "/usr/share/fonts/X11/75dpi/:unscaled"
    FontPath     "/usr/share/fonts/X11/Type1"
    FontPath     "/usr/share/fonts/X11/100dpi"
    FontPath     "/usr/share/fonts/X11/75dpi"
    FontPath     "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType"
    FontPath     "built-ins"
EndSection

Section "Module"
    Load  "dbe"
    Load  "dri"
    Load  "dri2"
    Load  "extmod"
    Load  "glx"
    Load  "record"
EndSection

Section "InputDevice"
    Identifier  "Keyboard0"
    Driver      "kbd"
EndSection

Section "InputDevice"
    Identifier  "Mouse0"
    Driver      "mouse"
    Option        "Protocol" "auto"
    Option        "Device" "/dev/input/mice"
    Option        "ZAxisMapping" "4 5 6 7"
EndSection

Section "Monitor"
    Identifier   "DisplayLinkMonitor"
EndSection

Section "Device"
    Identifier "DisplayLinkDevice"
    Driver        "fbdev"
    BusID         "USB"
    Option        "fbdev" "/dev/fb2"
EndSection


Section "Screen"
      Identifier "Screen0"
    Device "DisplayLinkDevice"
    Monitor "DisplayLinkMonitor"
    DefaultDepth 16
EndSection

Section "DRI"
    Mode    0666
EndSection