*Intro:* My screen randomly wakes up from standby / energy saving mode and it's a very very very annoying issue which cause I unfortunately have not the faintest clue about.
It is not something I can reproduce, so the best I can do is a sort of "case report". *What happened:* The screen woke up from energy saving mode all by itself. I just had done an upgrade, so the system was up to date. I had rebooted twice. The screen initially went in energy saving mode from sddm: there were no active session. I think there even have been no session between last reboot and screen-standby. Nobody was near the computer, and there was no earthquake at that time, nor any source of vibrations (note that I did try with mouses unplugged and that it made no difference). I took note of the time on my phone. When later I looked into "journalctl -a", there was no recorded events around the time of the incident. Not a line has been written in journalctl at or around that time. (My journalctl is on keep everything forever mode.) *The general setting:* It is an external screen connected to a lid-closed laptop through display port (Lenovo x230, intel integrated gpu; Monitor is 4K Dell; Connection is Display Port). I don't see anything else specific about it. I try never to do anything fancy with admin. *Why is it so annoying:* It is a huge distraction when the screen is turning on all by itself randomly. Due to the settings described above, I cannot turn the screen off using the physical button. My primary screen is the external screen. The lid of the laptop being closed, the screen of the laptop is altogether deactivated. This is the configuration recorded in settings and it works well. Now if I turn the external display off with the physical button: The above configuration is becoming unrealistic. Consequently the system has to go to a default realistic configuration, which it does very well: The laptop's screen becomes the primary display... But that changes all the settings. And since there is no different settings for different screens configurations, my settings are necessarily just ditched away. It would be too long to describe all the settings that are lost during this phase. With a 4K monitor on a 3rd generation i5, the gpu is already to the limit of what it can do. I "could" keep the lid of the laptop open, and the laptop screen not disabled, etc. But that would take more place on my desk, put additional strain on the system. As a consequence of all that, all I can do is turn the computer off. And with the lid closed and all that, the whole sequence is something very difficult to do.
