Closing the lid, going on the desktop to "gear"->suspend, or from terminal level calling
systemctl suspend ... all of this ends up with switching off the system.
One-by-one: I try to suspend the system and it goes black (as it should) immediately. There is no indication of powering off. When I press the trackpad (or open the lid) to wake-up, the system do full boot up (restart?). This is strange since if the system would be "truly" off it would not turn-on on trackpad press (or lid action).
/etc/systemd/logind.conf is not effecting anything. Also, there is nothing worrying in
/var/log/pm-suspend.log after pm-suspend.
All of this happened after I
oibaf/graphics-drivers (re-installing this PPA also doesn't solve the problem).
P.S. My machine: Dell XPS 9350 with Intel graphics