Linux 5.9 and Display Link

[andy_g]

Thanks for posting those instructions and I might try later but for now I'm just dropping back down to 5.8.X when I'm using DisplayLink as I'm worried, (as per some on that original thread) that this 5.9 patch will break 5.8.X

5.9 seems stable and I haven't hit any issues so far but haven't got hours to debug at the moment so might just stick on 5.8 until things are a bit more complete.

[bnavigator]

Originally Posted by andy_g

(as per some on that original thread) that this 5.9 patch will break 5.8.X

No need to worry in this regard. The voiced concerns in the original thread do have no factual grounds. If you look into the patch you will see all the modifications are wrapped in preprocessor macros to discriminate between kernel versions as it is already the case for API changes in previous kernels.

The way the evdi kernel module works: For every installed kernel version, DKMS compiles and installs a kernel module against the correct kernel headers.

You can switch between installed kernels and its respective kernel modules in your bootloader menu.

[andy_g]

Ok thanks for that follow up clarification - if I get a chance I will have a go.

[Crashdummy]

Hello there,

I hope this is still the valid topic for my question.

I am able to install the displaylink driver quite fine, however the Monitors connected thorugh Displayports refuse to work with this kernel.

I did a clean install of Pop OS 20.10.

|19:07:02|crashdummy@pop-os:[~]> uname -a && lsb_release -a
Linux pop-os 5.9.3-surface #1 SMP Wed Nov 4 03:03:11 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
No LSB modules are available.
Distributor ID:	Pop
Description:	Pop!_OS 20.10
Release:	20.10
Codename:	groovy

|18:59:24|crashdummy@pop-os:[~]> lsmod | grep evdi
evdi                   53248  4
drm_kms_helper        221184  2 evdi,i915
syscopyarea            16384  2 drm_kms_helper,evdi
sysfillrect            16384  2 drm_kms_helper,evdi
sysimgblt              16384  2 drm_kms_helper,evdi
drm                   544768  14 drm_kms_helper,evdi,i915

|18:59:25|crashdummy@pop-os:[~]> sudo dkms status
[sudo] password for crashdummy: 
evdi, 1.7.0, 5.9.3-surface, x86_64: installed
system76, 1.0.9~1597073326~20.10~5b01933, 5.8.0-7625-generic, x86_64: installed
system76, 1.0.9~1597073326~20.10~5b01933, 5.9.1-surface, x86_64: installed
system76, 1.0.9~1597073326~20.10~5b01933, 5.9.3-surface, x86_64: installed
system76_acpi, 1.0.2~1600812457~20.10~0bc966c, 5.8.0-7625-generic, x86_64: installed (original_module exists)
system76_acpi, 1.0.2~1600812457~20.10~0bc966c, 5.9.1-surface, x86_64: installed (original_module exists)
system76_acpi, 1.0.2~1600812457~20.10~0bc966c, 5.9.3-surface, x86_64: installed (original_module exists)
system76-io, 1.0.1~1559663713~20.10~ea5f61a, 5.8.0-7625-generic, x86_64: installed
system76-io, 1.0.1~1559663713~20.10~ea5f61a, 5.9.1-surface, x86_64: installed
system76-io, 1.0.1~1559663713~20.10~ea5f61a, 5.9.3-surface, x86_64: installed

|18:59:36|crashdummy@pop-os:[~]> xrandr --listmonitors
Monitors: 2
 0: +XWAYLAND0 2736/260x1824/170+2560+239  XWAYLAND0
 1: +XWAYLAND1 2560/700x1440/400+0+0  XWAYLAND1

I am using This Dock from i-tec

I did all these steps as instructed.
The only way the monitors can produce some output is by connecting them with HDMI.
As this dock has only one HDMI Port I can't work around this issue for now...

I use This Lenovo USB-C Dock frequently, too.
The Displays here are connect with displayports only, thus no display can be connected at all.

Both dockings were working quite fine till Kernel 5.7 ( haven't tested since then )

Logs have been attached

Update: Restarting the displaylink service appears to get the second monitor to run:

|12:44:33|crashdummy@pop-os:[~]> sudo systemctl restart displaylink-driver
|12:44:33|crashdummy@pop-os:[~]> systemctl status displaylink-driver 
● displaylink-driver.service - DisplayLink Driver Service
     Loaded: loaded (/lib/systemd/system/displaylink-driver.service; static)
     Active: active (running) since Sat 2020-11-28 12:44:26 CET; 37s ago
    Process: 19260 ExecStartPre=/bin/sh -c modprobe evdi || (dkms install $(ls -t /usr/src | grep evdi | head -n1  | sed -e "s:-:/:") && modprobe evdi) (code=exited, status=0/SUCCESS)
   Main PID: 19262 (DisplayLinkMana)
      Tasks: 48 (limit: 8913)
     Memory: 73.9M
     CGroup: /system.slice/displaylink-driver.service
             └─19262 /opt/displaylink/DisplayLinkManager

Nov 28 12:44:26 pop-os systemd[1]: Starting DisplayLink Driver Service...
Nov 28 12:44:26 pop-os systemd[1]: Started DisplayLink Driver Service.