DisplayLink
DisplayLink devices on Linux still only have experimental support. While some people have had success in using them, it is generally not an easy process and not guaranteed to work. The steps on this page describe the generally most successful methods of using external monitors with DisplayLink.
Also be warned that even over USB 3.0, a DisplayLink monitor may exhibit noticeably more lag than e.g. a DisplayPort monitor, especially when large portions of the screen are being redrawn.
Installation
USB 2.0 DL-1x5, DL-1x0 Devices
The kernel DRM driver for DisplayLink is udl, a rewrite of the original udlfb driver. It allows configuring DisplayLink monitors using Xrandr.
This should work without any configuration changes on linux 4.14.9-1 and later. If you are using an earlier version of that package or have CONFIG_FB_UDL=m set in your kernel config, you need to blacklist the old kernel module, udlfb, which may attempt to load itself first.
USB 3.0 DL-6xxx, DL-5xxx, DL-41xx, DL-3xxx Devices
- Install evdiAUR or evdi-gitAUR for the in development kernel module.
- Install the displaylinkAUR driver. For Xorg it allows configuring DisplayLink monitors using Xrandr in the same manner as the
udldriver; for Wayland no configuration is necessary. - Enable
displaylink.service. - For Xorg use the "modesetting" driver with AccelMethod "none" and MatchDriver "evdi".
Create a file with the following content:
/etc/X11/xorg.conf.d/20-evdi.conf
Section "OutputClass" Identifier "DisplayLink" MatchDriver "evdi" Driver "modesetting" Option "AccelMethod" "none" EndSection
A reboot may be required for the setting to be effective.
Setting up X Displays
After that, run:
$ xrandr --listproviders
Providers: number : 2 Provider 0: id: 0x49 cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 2 outputs: 8 associated providers: 0 name:Intel Provider 1: id: 0x13c cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 0 name:modesetting
In the above output, we can see that provider 0 is the system's regular graphics provider (Intel), and provider 1 (modesetting) is the DisplayLink provider. To use the DisplayLink device, connect provider 1 to provider 0:
$ xrandr --setprovideroutputsource 1 0
and xrandr will add a DVI output you can use as normal with xrandr. This is still experimental but supports hotplugging and when works, it is by far the simplest setup. If it works then everything below is unnecessary.
Configuration
These instructions assume that you already have an up and running X server and are simply adding a monitor to your existing setup.
Load the framebuffer device
Before your system will recognize your DisplayLink device, the udl kernel module must be loaded. To do this, run
# modprobe udl
If your DisplayLink device is connected, it should show some visual indication of this. Although a green screen is the standard indicator of this, other variations have been spotted and are perfectly normal. Most importantly, the output of dmesg should show something like the following, indicating a new DisplayLink device was found:
usb 2-1.1: new high-speed USB device number 7 using ehci-pci usb 2-1.1: New USB device found, idVendor=17e9, idProduct=03e0 usb 2-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 usb 2-1.1: Product: Lenovo LT1421 wide usb 2-1.1: Manufacturer: DisplayLink usb 2-1.1: SerialNumber: 6V9BBRM1 [drm] vendor descriptor length:17 data:17 5f 01 00 15 05 00 01 03 00 04 udl 2-1.1:1.0: fb1: udldrmfb frame buffer device [drm] Initialized udl 0.0.1 20120220 on minor 1
Furthermore, /dev should contain a new fb device, likely /dev/fb1 if you already had a framebuffer for your primary display.
To automatically load udl at boot, create the file udl.conf in /etc/modules-load.d/ with the following contents:
/etc/modules-load.d/udl.conf
udl
For more information on loading kernel modules, see Kernel modules#Automatic module loading with systemd.
Configuring X Server
Use xrandr or your Desktop Environment's display setup UI to configure your USB monitors running either the udl or displaylink driver.
xrandr
Once the driver is loaded, the DisplayLink monitor is listed as an output provider:
$ xrandr --listproviders
Providers: number : 2 Provider 0: id: 0x43 cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 2 outputs: 2 associated providers: 1 name:Intel Provider 1: id: 0xcb cap: 0x2, Sink Output crtcs: 1 outputs: 1 associated providers: 1 name:modesetting
In the above example, provider 1 is the DisplayLink device, and provider 0 is the default display. Running xrandr --current gives a list of available screens:
$ xrandr --current
Screen 0: minimum 320 x 200, current 1600 x 900, maximum 8192 x 8192
LVDS1 connected 1600x900+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
1600x900 60.0*+ 40.0
1440x900 59.9
1360x768 59.8 60.0
1152x864 60.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
VGA1 disconnected (normal left inverted right x axis y axis)
DVI-1-0 connected (normal left inverted right x axis y axis)
1366x768 60.0 +
1368x768_59.90 59.9
1368x768_59.90 (0xd0) 85.7MHz
h: width 1368 start 1440 end 1584 total 1800 skew 0 clock 47.6KHz
v: height 768 start 769 end 772 total 795 clock 59.9Hz
If the above does not list the DisplayLink screen, then you will need to offload DisplayLink to the main GPU:
xrandr --setprovideroutputsource 1 0
Once the screen is available, refer to Xrandr for info on setting it up. For automating the configuration process, see displaylink.sh.
Enabling DVI output on startup
The DisplayLink provider will not be automatically connected to the main provider in most cases, therefore the DVI output device will not be available. It can be helpful to automatically do this when X starts to facilitate automatic display configuration by the window manager.
Edit your desktop manager's startup configuration and add commands similar to:
$(xrandr --listproviders | grep -q "modesetting") && xrandr --setprovideroutputsource 1 0
For example, the appropriate startup configuration file for SDDM is /usr/share/sddm/scripts/Xsetup.
Avoid placing these commands in ~/.xprofile as this breaks the display configuration of some window managers. Instead these commands should be run prior to any display output or setup.
modesetting
Switching between displaylink and nvidia/nouveau driver
As of displaylink version 1.3.54-1 it is not possible to use displaylink device and NVIDIA/nouveau driver simultaneously on Optimus based laptops. Currently to be able to use displaylink device on Intel GPU, you should create a configuration file (see #Troubleshooting below). However, with that configuration file it is not possible to use primusrun. Bumblebee service is running, but it cannot work. Also, the laptop fans are becoming very noisy and the laptop temperature becomes very high. When you want to switch back to activate NVIDIA driver, comment everything in that file and reboot.
To simplify process of switching, you can install dl-switchAUR and add an additional menu entry to your bootloader using the kernel parameter systemd.unit=displaylink.target, thus activating displaylink workaround.
To check which driver is used for your discrete video card, run lspci -nnk -s xx:xx.x (replace xx:xx.x with your NVIDIA GPU PCI id).
Troubleshooting
Not working configuration
These are tested on Xfce using Display settings (included in XFCE4 package) and external tool - arandr. XFCE4 Display settings are likely to crash, so ARandR might help.
When you connect display link device via USB to your computer, the computer should show monitors in Display settings. There are few troubleshooting steps that you should try:
- Check #Setting up X Displays. If you can find any external monitors recognized, you should try to make them visible by the following commands:
xrandr --setprovideroutputsource 1 0 xrandr --setprovideroutputsource 2 0 xrandr --setprovideroutputsource 3 0 ...
This will make them visible and recognized in Display settings.
- Restart
displaylink.service. - Re-connect the USB cable.
- Check if
udldriver is loaded and monitors are connected.
Screen redraw is broken
If you are using udl as your kernel driver and the monitor appears to work, but is only updating where you move the mouse or when windows change in certain places, then you probably have the wrong modeline for your screen. Getting a proper modeline for your screen with a command like
gtf 1366 768 59.9
where 1366 and 768 are the horizontal and vertical resolutions for your monitor, and 59.9 is the refresh rate from its specs. To use this, create a new mode with xrandr like follows:
xrandr --newmode "1368x768_59.90" 85.72 1368 1440 1584 1800 768 769 772 795 -HSync +Vsync
and add it to Xrandr:
xrandr --addmode DVI-0 1368x768_59.90
Then tell the monitor to use that mode for the DisplayLink monitor, and this should fix the redraw issues. Check the Xrandr page for information on using a different mode.
If this does not solve the problem (or if the correct modeline was already in place because of correct DDC data), it can help to run a compositor.
Ghosting
If you experience ghosting caused by moving the cursor around, it might happen that your compositor configuration is causing the problem. Changing settings may give you a working setup.
DisplayLink refresh rate is extremely slow with gnome 3
If once you set up your DisplayLink your entire desktop becomes slow, try setting a "simpler" background image, such as complete black.
All displays' are capped to 1 FPS when disabling builtin screen
Applying the patch from https://gitlab.freedesktop.org/xorg/xserver/-/issues/1028#note_504826 to xorg-server seems to fix the problem.
Slow redraw/Unresponsiveness in Google Chrome and Webkit2-based Applications
This is to be associated with bugs in hardware acceleration, which can be tested by running glxgears in the displaylink screen resulting in 1fps. There is currently no complete fix available, but turning off Hardware-Acceleration in affected applications can work as a temporary fix.
This can be done in applications without a hardware-acceleration option by prepending the LIBGL_ALWAYS_SOFTWARE=1 environment variable.
Impossible to activate displaylink's screen
In case you are able to see attached monitor via DisplayLink device in your screen settings, but after you turn it on and apply settings, it becomes deactivated, then try blacklist nouveau module and reboot:
/etc/modprobe.d/nouveau.conf
blacklist nouveau options nouveau modeset=0
Suspend problem
Displaylink is not working after suspend. Unplug and then plug again displaylink's usb cable to your computer. Monitor that is connected via DisplayLink will remain black. If you have lock screen, login to the system and then picture will appear at that monitor and you will be able to use displaylink as normal.
DisplayLink is not working when usb hot plugged
To be able to use DisplayLink monitors, its usb cable should be attached to laptop during boot time. Otherwise it can behave like they are available and mouse can be moved there, but its picture is frozen, even with correct configuration (see workaround 1). If it was not attached at boot time, attach it and reboot.
DisplayLink driver does not work with Intel GPUs after recent X upgrades
As this support page says, upgrading the X Window Server to a version newer than 1.18.3 will make the system not compatible with DisplayLink by default. This applies to systems using an integrated Intel GPU, or a combination of integrated Intel GPU and a discrete GPU. Until fixes in X Windows System will be released, there are two workarounds:
Workaround 1: Use older intel driver as a fallback
Use the "intel" driver for the integrated GPU instead of "modesetting", which is now the default.
Create a file with the following content:
/usr/share/X11/xorg.conf.d/20-displaylink.conf
Section "Device" Identifier "Intel Graphics" Driver "intel" EndSection
A reboot is required for the setting to be effective.
You may need the evdi-gitAUR package.
Workaround 2: Temporarily disable PageFlip for modesetting
For users that prefer to keep using "modesetting" driver, disabling page flipping should also help.
Create a file with the following content or extend the PageFlip option to an existing configuration file (e.g. 20-evdidevice.conf):
/usr/share/X11/xorg.conf.d/20-displaylink.conf
Section "Device" Identifier "DisplayLink" Driver "modesetting" Option "PageFlip" "false" EndSection
Displays disconnect at random intervals when using the Dell D6000 docking station
User's have reported that when using the Dell D6000 docking station, their display(s) may disconnect at random intervals during usage. This will require physically reconnecting the dock in order to reinitialise the displays.
This issue appears to be caused by PulseAudio's module-suspend-on-idle module, which automatically suspends sinks/sources on idle.
To disable loading of the module-suspend-on-idle module, comment out the following line in the configuration file in use (~/.config/pulse/default.pa or /etc/pulse/default.pa):
/etc/pulse/default.pa
### Automatically suspend sinks/sources that become idle for too long # load-module module-suspend-on-idle
Only 1 Display is recognized after boot
In case multiple displays are connected to a DisplayLink Docking station, but only 1 is recognized after bootup, a possible fix is to force evdi to search for multiple displays at boot by adding the evdi module to /etc/modules-load.d/evdi.conf and "options evdi initial_device_count=2" to /etc/modprobe.d/dkms.conf
DisplayLink and NVIDIA dGPU on X11 (Optimus+DL)
If a laptop using NVIDIA Optimus is in a more permanent setting (using X11), it is nice to permanently set video outputs to use the dGPU. nvidia-xconfig might produce the following:
/etc/X11/xorg.conf
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0"
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
EndSection
# ...
# Keyboard0
# Mouse0
# ...
Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Unknown"
Option "DPMS"
EndSection
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BusID "PCI:1:0:0"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 24
EndSubSection
EndSection
Even after installing both evdiAUR and displaylinkAUR packages, the DisplayLink connected displays still might not appear. Manually, we can instruct Xorg to use the modesetting plugin with the video interface given by the displaylinkAUR driver.
1. Identify which DRI device
The easiest way to identify which device is to run ls -al /dev/dri/by-path
$ ls -al /dev/dri/by-path
total 0 drwxr-xr-x 2 root root 160 May 11 19:10 . drwxr-xr-x 3 root root 180 May 10 16:03 .. lrwxrwxrwx 1 root root 8 May 10 16:03 pci-0000:00:02.0-card -> ../card0 lrwxrwxrwx 1 root root 13 May 10 16:03 pci-0000:00:02.0-render -> ../renderD128 lrwxrwxrwx 1 root root 8 May 11 19:10 pci-0000:01:00.0-card -> ../card1 lrwxrwxrwx 1 root root 13 May 10 16:03 pci-0000:01:00.0-render -> ../renderD129 lrwxrwxrwx 1 root root 8 May 10 16:03 platform-evdi.0-card -> ../card2 lrwxrwxrwx 1 root root 8 May 10 16:03 platform-evdi.1-card -> ../card3
As you can see, the first evdiAUR device is /dev/dri/card2
2. Add the following to the Xorg config:
/etc/X11/xorg.conf
# Add the following to the ServerLayout section after Screen0
# ...
Screen 1 "Screen1"
# ...
# ... at the end, add:
Section "Device"
Identifier "usbdev"
Driver "modesetting"
Option "kmsdev" "/dev/dri/card2"
EndSection
Section "Screen"
Identifier "Screen1"
Device "usbdev"
EndSection
3. Restart the X server to see changes.
4. The DL displays should appear. Configure using Xrandr as necessary.
See Also
- DisplayLink Open Source: Official DisplayLink open source support forum
- Plugable: Vendor blog chronicling Linux support for DisplayLink.