Computer won't wake from sleep after suspend [xfce, debian testing]

Question

So, ever since I switched to xfce, I have been having some issues with suspending my system.

My system wakes from sleep normally most of the time, but every once in a while, my computer will turn on, and my status lights will turn on, but my screen won't initiate. I really have no idea why this happens, and it's been bothering me for too long.

I have a sneaking suspicion it has to do with xscreensaver. This is because I have disabled it, but I managed to wake my computer immediately one time and was greeted both to the lightdm login screen, then afterwards the xscreensaver login, which shouldn't be there.

Answer 1

Removing light-locker and using lightdm solved the problem for me on Debian 10.

$ sudo apt install lightdm
$ sudo apt remove light-locker

On Thinkpad T410.

Answer 2

If restarting LightDM after switching+log-in in the text console helps, then you can try this solution, found originally here: In the VT1 console, you can write this 1-line script:

while true; do DISPLAY=:0 xrandr --auto && break || sleep 1s; done

It will start looping. Then you switch to the GUI console (Ctl-Alt-F7), and in 1 second it should become active, with login prompt. If this works, we can create a fully automatic solution.

Answer 3

Some kernel version have problems waking from a deep-sleep. Go into your BIOS and search for "C States" or "Sleep states" or similar. Change the maximum value to 1, or even to off, and see if that removes the problem. These "C States" are used to moderate the CPU power consumption, so you want to allow the highest-value state that your kernel will wake up from.