[Intel-gfx] Problems with external monitor and Intel HD 520

[Mário Antunes]

Hello,

I am having problems connecting a external monitor to my laptop using a 
intel HD 520 GPU and a Thunderbolt 3 adapter (Dell DA200).
My laptop is a Dell XPS 13 9350, running Slackware64-current with kernel 
4.4.
Dmesg shows several errors related to the i915 kernel module.

What can I do? Do you want some logs to check what is happening?

Mário Antunes