My laptop is connected to an external monitor via DisplayPort(in a port in the docking station). When I boot my laptop while it is connected to the docking station everything works fine, but if I detach the laptop from the docking station and reattach it, the external monitor does not wake up. It does recognize something happened, as it display a power-saving mode message, but, but it remains black. The laptop itself thinks it's connected, as it switches to the multi-monitor mode.I'm running Arch Linux on a Dell Latitude E7440 with kernel version 3.16.1-1-ARCH and KDE 4.14.0. I have the xf86-video-intel driver installed. I'm using kscreenfor monitor management, but even if I go to the system settings to set it up manually I can't wake up the screen.When I connected the same screen via DVI it worked fine.
DisplayPort won't wake up screen when laptop placed in docking station
arch linux;kde;displayport
The solution was to install Laptop Mode Tools.