Ubuntu – Blank screen after resume from suspend on 18.04 on HP Elitebook 850 G5 (Intel HD graphics)

18.04hpintel graphicspower-managementsuspend

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

UPDATE:

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.

Best Answer

Solution:

Properly (click) blacklist amdgpu, even if you think you're not using it.

Explanation/story:

I thought I had properly tried the amdgpu blacklist fix, but apparently something went wrong. I didn't bother to double-check, since I didn't have an AMD video card.

However, when running gpu-manager, it said

Is amdgpu blacklisted? no

Is amdgpu loaded? yes

This got me somewhat confused so I get checked lspci output again, and sure enough:

01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Polaris12 (rev c3)

So yeah, I guess my graphics processing is still done by Intel HD Graphics, but the device that actually handles displaying those graphics is apparently made by AMD. This also explains why the issue was still present when booting in emergency mode: you're not loading your video card drivers, but you are using your display controller (and hence also its drivers).

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