Comment 58 for bug 1530171

I am tested wily ,xenial, kubuntu, kernels 4.2 , 4.4 on brand new thinkpad t450s with thinkpad pro dock 90w.
The laptop and the dock has latest fimware !
Intel graphics driver is at latest state too.
Also tested latest 4.5 drm intel nightly. All external displays work always when directly attached to the laptop.
But with laptop docked, external displays are only running after boot, but fail when wake up from sleep mode configured in kde
closing lid. This is a very common user powersetting an is awaited to work. Most of the times external displays could reconfigured i.e by script produced from arandr ( gtk gui wrapper for xrandr ). But a universal script workaround seems complicated with acpi, systemd in userland for all thinkable combinations of possible displays ( up to three include lcd on laptop are possible).

It should simply work out of the box.

Additional info i invested a lot of time in kernel logs and trying grub start parameter, cause there were other ugly bug with intel 915 driver ( pci lied SDE etc fixed in 4.5 ) , there is also a point in the bios configure 10s to wait for notice external displays. Also 2014 the dock had a bug ( also on windows with external displays which was fixed by new firmware ).
It seems simply the dock does not pass external displays connected after laptop and external displays got sleep mode after wake up, prove is made by plug/unplugging external display and reenable it in kde. Also open windows were only reconstructed
after awake with kernel 4.4 /4.5 after manual reenable, with kernel 4.2 most of the time also plasma crashes and simply undock
crash x-server too. Any idea what to look next ?
Regards