Blank screen after resume from suspend on
- HP Elitebook 850 G5
- Intel HD graphics (no dedicated GPU)
- Ubuntu 18.04
After powering on the laptop to resume, the screen remains blank although the power, numlock and wifi buttons light up. Symptoms:
- Numlock LED is unresponsive after being pressed, but fn-lock LED is responsive.
- Ctrl+Alt+F1 and other TTYs don't work.
- I'm not sure how to do Alt+SysRq+B on this machine (there is no sysrq button, only print screen as an fn-alternative for right shift...) but I tried many options and it doesn't seem to work.
- The /var/log/kern.log shows no entry whatsoever between the suspend operation and the next boot (after i forced shutdown by holding the power button since the resume did not work):
Jul 28 10:54:16 pdiracdelta-laptop kernel: [ 59.031360] PM: suspend entry (deep) Jul 28 10:58:36 pdiracdelta-laptop kernel: [ 0.000000] Linux version 4.15.0-29-generic (buildd@lgw01-amd64-057) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #31-Ubuntu SMP Tue Jul 17 15:39:52 UTC 2018 (Ubuntu 4.15.0-29.31-generic 4.15.18)
Attempted fixes that did not work:
blacklist amdgpu (I don't even have an amd gpu but I'm that hopeless...)<-- this turned out to be the solution
- add to GRUB: nouveau.modeset=0 (does linux even use Nouveau for Intel HD Graphics?)
- disable BIOS fastboot and deep sleep
Even when booting into emergency mode and doing suspend+resume from there, the system is frozen with a black screen. So my guess is that it's got nothing to do with the display drivers.
How do I fix this, or even just debug this issue?
P.S.: For what it's worth: I was using Xubuntu 16.04 on the Elitebook 850 G3 without this issue.