Screen switches off after successful lightdm login from suspend

[George White]

On a ThinkPad E465 with dual AMD graphics (both integrated AMD Radeon R6 and dedicated Radeon R5 graphics) running Xubuntu 18.04 Bionic Beaver, when opening the lid, lightdm asks for my password, after successfully unlocking the device, the screen goes black with the backlight on for a second, then switches off entirely (nothing is visible at all, regardless of whether there is light incident on the screen or not), but Xfce still works, notifications still sound etc.

When closing the laptop lid again, causing it to go back in to suspend, then opening the lid again, the screen switches back on, briefly (less than a second) displays PCI-related messages on a tty before lightdm appears, and I can continue to Xfce like normal. Switching to tty1 clears the screen and these lines don't appear in dmesg at all.

However, the system appears unstable. When the problem occurred for the first time, Firefox froze, apt froze when executed from a terminal window (though apps launched from the Xfce menu worked fine), both requiring 'kill' in Task Manager.

Thus, I used Xfce to reboot the machine, but stop jobs ran what appeared to be indefinitely for CUPS and PackageKit, presumably because they too froze.

As long as the system didn't suspend during the uptime, the system works like a charm and I've had no other issues or stability complaints.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7
ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18
Uname: Linux 4.15.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: XFCE
Date: Thu Jul 5 15:28:03 2018
DistUpgraded: Fresh install
DistroCodename: bionic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Carrizo [1002:9874] (rev c5) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Carrizo [17aa:5116]
InstallationDate: Installed on 2018-07-05 (0 days ago)
InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
MachineType: LENOVO 20EXS00E00
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-23-generic root=UUID=021ff1ca-dcb1-4671-aa42-06a05e147f88 ro quiet splash vt.handoff=1
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/20/2017
dmi.bios.vendor: LENOVO
dmi.bios.version: R01ET41W (1.21 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20EXS00E00
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrR01ET41W(1.21):bd12/20/2017:svnLENOVO:pn20EXS00E00:pvrThinkPadE465:rvnLENOVO:rn20EXS00E00:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.family: ThinkPad E465
dmi.product.name: 20EXS00E00
dmi.product.version: ThinkPad E465
dmi.sys.vendor: LENOVO
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.0~rc5-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.0~rc5-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[George White (galexite)]

Hmm. `xrandr --listmonitors` gives two monitors connected:

  george@ThinkPad-E465:~/Documents/bug$ xrandr --listmonitors
  Monitors: 2
    0: +*eDP 1366/309x768/173+0+0 eDP
    1: +*eDP 1366/309x768/173+0+0 eDP

There is only one monitor on this laptop, the internal display.

[George White (galexite)]

Ah. `radeon` and `amdgpu` are trying to load together, that may not be helping:

  george@ThinkPad-E465:~$ cat /var/log/Xorg.0.log.old | grep amdgpu
  [ 29.119] loading driver: amdgpu
  [ 29.119] (==) Matched amdgpu as autoconfigured driver 0
  [ 29.119] (II) LoadModule: "amdgpu"
  [ 29.119] (II) Loading /usr/lib/xorg/modules/drivers/amdgpu_drv.so
  [ 29.143] (II) Module amdgpu: vendor="X.Org Foundation"
   All GPUs supported by the amdgpu kernel driver
  [ 29.235] (EE) AMDGPU(G0): amdgpu_device_initialize failed
  [ 29.610] (II) UnloadModule: "amdgpu"

This is a fresh installation. I've never picked either driver, and nothing appears in Additional Drivers.

[George White (galexite)]

Uninstalling the `radeon` drivers, but keeping the `amdgpu` drivers, fixes the problem. Therefore, this is not an Xorg bug.

[George White (galexite)]

Moved to amdgpu. The problem appears to be a conflict between amdgpu and radeon, both of which were installed automatically on a fresh Xubuntu 18.04 install.