[amdgpu] Boot into black screen without power supply (Kubuntu on AMD)

[snow]

Always when I turn on my Lenovo Thinkpad T495 (AMD CPU)- without the power supply connected - the laptop boots correctly at the beginning, but then just before going to the login screen it gets black. It can only be restarted. When I attach the power supply before the laptop boot everything works correctly. I see this behavior only on Kubuntu (with KDE desktop). On Ubuntu 20.04 everything works fine.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu26
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompositorRunning: None
CurrentDesktop: KDE
Date: Mon Apr 13 14:20:17 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: I just need to know a workaround
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Picasso [1002:15d8] (rev d2) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Picasso [17aa:5125]
InstallationDate: Installed on 2020-04-02 (10 days ago)
InstallationMedia: Kubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200401)
MachineType: LENOVO 20NKS01Y00
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-21-generic root=UUID=d6957960-70a9-45a8-98b1-b0a14d07b829 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 10/28/2019
dmi.bios.vendor: LENOVO
dmi.bios.version: R12ET46W(1.16 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20NKS01Y00
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrR12ET46W(1.16):bd10/28/2019:svnLENOVO:pn20NKS01Y00:pvrThinkPadT495:rvnLENOVO:rn20NKS01Y00:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad T495
dmi.product.name: 20NKS01Y00
dmi.product.sku: LENOVO_MT_20NK_BU_Think_FM_ThinkPad T495
dmi.product.version: ThinkPad T495
dmi.sys.vendor: LENOVO
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-1
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.4-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.7-2ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20190815-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[snow (mrauschert)]

I tested again. THis time I got the login screen and logged in then the screen got distorted as the display manager would not work correctly. I did "journalctl -b 0" and found also a crash file in var/crash/...
I attach both files here.

[snow (mrauschert)]

I tested again. THis time I got the login screen and logged in then the screen got distorted as the display manager would not work correctly. I did "journalctl -b 0" and found also a crash file in var/crash/...
I attach both files here.

[snow (mrauschert)]

and crash file.

[snow (mrauschert)]

Meanwhile after some updates I manage to login even without power supply. After that the screen is distorted and looks like this - s. attachment. In the screen you see right a shadow - my taskbar. You can only see the top bar of windows.

[Neil (neile)]

This affects me too - Ubuntu MATE 20.04, Lenovo T495 (so AMD graphics/amdgpu).

Boots fine with power supply connected, but running from battery, laptop POSTs ok, displays grub, displays boot msgs but then screen goes blank. Happy to provide logs if you let me know what you need, I can SSH into the laptop to retrieve whatever is required.

Thanks.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Neil (neile)]

I've managed to get the system to boot when not plugged into mains by adding 'iommu=soft' to the linux line in grub.

Not sure at what cost but at least I don't lose my display info like when nomodeset is used.

[Neil (neile)]

Just to provide a source, I got it from here (where it seems other people have the same issue):

https://askubuntu.com/questions/1206472/ubuntu-18-04-and-20-04-stuck-on-gnome-startup-on-battery-only

[hboetes (hboetes)]

I noticed the same problems and a few more. For example closing the lid hangs the system. Disconnecting the power supply hangs the system. All clearly kernel related.

I tried the iommu=soft solution which didn't work for me. Also adding amd_iommu=pt didn't help.

The best fix I found so far was upgrading to a more recent kernel. i.e. Get this script: https://github.com/pimlie/ubuntu-mainline-kernel.sh
And install the latest kernel.

[snow (mrauschert)]

iommu=soft as workaround helped me (ThinkPad T495 / AMD)

[Michael Grupp (michaelgrupp)]

The iommu=soft workaround works for me. Without it my T495 was pretty much useless with Ubuntu.

Here are some detailed instructions for mere mortals:
https://www.reddit.com/r/thinkpad/comments/eb08hk/t495_unplugged_battery_broken_boot_with_linux/

Does anybody know by chance when and how one can install a somewhat supported Kernel package that has the fix?

[Scarlett Gately Moore (scarlettmoore)]

This bug is very old, if it is still an issue please update the bug with information from a supported release.