I'm on debian stretch, and my computer is a MacBookPro 12,1. I've recently
noticed an issue that affect my system when it hibernates.
When the screen is already switched off and then the system hibernates, it
won't resume correctly later on. Specifically, the monitor will be switched off
again at the end of the resume process.
E.g. I give the following command in order to switch off the monitor:
$ sleep 1 && xset dpms force off
then I close the lid so that my system hibernates. Then I resume the system.
The monitors turns on, as I see the boot loader screen and some boot messages.
But then, when the resume is complete, the screen is switched off again, and
there is no way to turn it on. The only solution is press the power button to
turn off the entire computer.
I get the same issue even when, instead of using the xset command, I wait
several minutes so that the screen is switched off automatically by KDE's
power management, and then I hibernate the system.
By contrast, I have no issue if I hibernate when the screen is still on. The
resume works perfectly well. Besides, suspend (to RAM) has no issue either,
both when the screen is on and when it is off.
I've already reported a bug to the mainteiners of debian kernel. But in the
meanwhile, as a workaround I'm thinking of using a systemd script that forces
the monitor on just before the system starts hibernating. I've tried with
"xset dpms force on", however it won't in fact turn on the monitor. Is there a
way to do this?
Thanks & Regards,
Davide