USB 3.0 displays are black on Ubuntu after x.org update to 1.18.3 or newer

[Szymon Kunc]

[Impact]

 * This impacts all Ubuntu releases which received an update of x.org to 1.18.3 or newer, i.e. Ubuntu 16.04, 16.10, 17.04 & 17.10

 * End users are unable to use their USB displays unless they workaround the problem which currently involves disabling pageflip for modesetting in x.org.conf file

 * The fix which has been submitted to x.org extends blacklisting mechanism so the EVDI kernel module which is essential for DisplayLink USB 3.0 devices to work is correctly recognised by x.org. Then the PRIME sync is disabled in such case; The patch can be found here: https://cgit.freedesktop.org/xorg/xserver/commit/?id=fbd80b2c8ebe9fd41229dc5438524d107c071ff1

[Test Case]

1. On a PC device with Ubuntu install DisplayLink SW for Ubuntu v1.3.54 downloaded from http://www.displaylink.com/downloads/ubuntu. Detailed requirements and instructions can be found here:
2. Plug in a DisplayLink USB 3.0 compatible device, e.g. Dell D3100 docking station
3. Plug in an external monitor (HDMI or DisplayPort) to the docking station

Expected result:
The external monitor should light up and show the desktop

Actual result:
The monitor remains black or shows frozen desktop.

[Regression Potential]

 * The patchset extends number of modules for which x.org changes its functionality. It checks if "evdi" string is in the syspath so it is quite unlikely there would be any impact on anything else then USB 3.0 displays which use EVDI module.

[Other Info]

 * The patch has been applied to Ubuntu x.org source code built and tested.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Christopher M. Rogers (cajhne)]

Same result on Ubuntu 17.10 - black screen with cursor on USB monitor running on displaylink driver as mentioned above.

[Timo Aaltonen (tjaalton)]

I've proposed to add the patch to upstream 1.19 branch, 1.19.4 is about to be released.

[Szymon Kunc (spkunc)]

Hi Timo,

Thanks for the actions taken so far.
Any chance to port this patch to branch 1.18 as well?

Szymon

[Mario Limonciello (superm1)]

16.10 is EOL already, so it won't be possible to fix there. I've nominated it for the other releases though that got 1.18.3.

[Christopher Carr (cacarr)]

Please excuse me if this is not the appropriate place to report this.

A heads-up for current versions of xorg-server: there appears to be an additional or separate issue with DisplayLink and xorg-server > 1.19.6. 1.20+ doesn't work at all. A display plugged in prevents logging in, and plugging in kills the session and drops you back to login -- at least on Arch.

https://github.com/DisplayLink/evdi/issues/133

[Timo Aaltonen (tjaalton)]

fixed upstream

[Timo Aaltonen (tjaalton)]

and the patch is in -hwe-16.04 backport for xenial