Arch Linux

squalou

Member

Registered: 2018-06-04

Posts: 112

evdi / displaylink dell xps13 + D6000 station : screen artifacts

Hi,

I've followed this : https://wiki.archlinux.org/index.php/DisplayLink
and ... it used to work. (that's for the quick story )

Now, let's explain all.

Thing is, at work, most of the time I don't use D6000 station at all, I use a usb-c monitor instead. Which works out of the box.

After months without trying, last week I had to plug again to a D6000 Displaylink station.

=> monitor displayed horrible horizontal lines, garbled desktop background, and no way to use it. I mean : no way to move a window there (even unreadable). It's as if a garbage image had bee drawn and stood statically there.

So , I ended up with the "workaround 2" mentioned in the wiki article forementioned. (workaround 1 had no effect)

/usr/share/X11/xorg.conf.d/20-evdidevice.conf

/usr/share/X11/xorg.conf.d/20-displaylink.conf
Section "Device"
  Identifier "DisplayLink"
  Driver "modesetting"
  Option "PageFlip" "false"
EndSection 

And now ... it works well with D6000 station ... but not well at all when not using the station !  (which is, remember : most of the time)
Symptoms :
- when scrolling in a web page for instance, refresh is 'lagging', producing an horizontal 'band' where image looks like water was poured over the screen and image was 'liquid'. Back to normal when image does not move.
- when moving a window, there's a kind of 'checker' that is displayed in the moving window.

It's as if refresh was too slow.

What is really annoying, is that
- with a fresh reboot
- lsmod not even showing evdi
- ... I still have the issue

So, I really don't understand how the "tweak" mentioned in above 'workaround' can have any effect... when not using displaylink

And that's the point of this topic

I would really appreciate a situation when I have 'normal' behaviour, then why not, when I plug a displaylink device (once every now and again), I end up with annoying artifacts but can work until next reboot.

I've tried with up-to-date kernel and lts-kernel alike. Tried evdi-git too.

I've tried to mix the 'workaround' adding a

MatchDriver "evdi"

line, wich prevented to start X altogether

Any clue / explanation / idea of experimentation is welcome !

thanks for reading

Last edited by squalou (2019-10-17 15:18:07)

squalou

Member

Registered: 2018-06-04

Posts: 112

Re: evdi / displaylink dell xps13 + D6000 station : screen artifacts

Also, note taht if I ever add

Option  "AccelMethod" "none" 

then displaylink monitors do not display at all, and on regular monitors, no more issues.
(no errors seen in logs when plugin in displaylink things, journalctl -u displalink doesn't coplain, evdi modules appears in lsmod, just ... nothing gets displayed)