[amdgpu] [AMD Renoir] Display won't rotate, nor do fractional scaling, but amdgpu.exp_hw_support=1 fixes it

[John Gilmore]

Opening Settings -> Display and selecting an orientation other than Landscape doesn't work. Similarly, selecting Fractional Scaling and then picking a scale factor has no effect.

This is a recently installed Ubuntu 20.04, fully updated, on a recently released laptop/tablet that uses an AMD Ryzen 4500U integrated CPU/GPU. It is possible that the GPU is not being detected by Ubuntu and that is the root cause of the problem. I couldn't find an easy explanation online about how to tell whether a GPU was detected or is in use. I did try running "tlp-stat -g" to get graphics status, but it returns without printing anything except its version number (1.3.1).

When I choose an orientation, such as Portrait Right, the setting changes and an "Apply" button appears in the top of the Settings window. When I press it, up pops up a dialog asking whether I want to "Keep these display settings?" with two options, keep or revert. The rest of the screen goes grey behind the dialog box, but I can already see behind the popup that the screen did not change its orientation, and the "Orientation" setting back in the Settings->Display window has been reverted to "Landscape" without me doing it. Whether I choose keep or revert, or merely let it time out after 20 seconds, the result remains the same -- the display stays in Landscape mode and the setting that I had made is reverted.

Regarding scaling, I can set the display scale to 100% (default) or 200%, successfully. But when I turn on the "Fractional Scaling" slider, the graphics around the edge of the screen immediately increase in size (the icons in the left-hand dock, the text in the top bar), even though I have not changed the scale setting. I have included two screenshots (original screen, and with Fractional Scaling on). There is also some strangeness about whether sliding the Fractional Scaling slider updates the Scale menu to allow more scales - sometimes it does, sometimes it doesn't.

When I attempt to set a fractional scale such as 125%, the "Apply" button appears in the upper right corner. When I press that, the display does not actually scale, and a pop-up asks if I want to keep or revert the setting. But looking back at the Displays settings, the Scale has already reverted to 100% (as above with the Orientation). Screenshot enclosed.

The display has been rock-solid before this, but now it started showing artifacts, such as previous copies of the Displays window. I've enclosed a screen shot, which shows checkerboard in the screen locations that (in reality) were displaying prior versions of the window. Hmm, examining that screenshot, it looks like the display DID start occupying 25% more space horizontally and vertically, but something about the video scanning versus the screen updating got out of whack.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-40.44-generic 5.4.44
Uname: Linux 5.4.0-40-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.4
Architecture: amd64
BootLog:

CasperMD5CheckResult: skip
CompositorRunning: None
Date: Sat Jul 18 14:00:38 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Renoir [1002:1636] (rev c3) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Renoir [17aa:3f1a]
InstallationDate: Installed on 2020-07-16 (1 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: LENOVO 81X2
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-40-generic root=/dev/mapper/vgubuntu-root ro quiet splash acpi_enforce_resources=lax vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/08/2020
dmi.bios.vendor: LENOVO
dmi.bios.version: EECN20WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40700 WIN
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 31
dmi.chassis.vendor: LENOVO
dmi.chassis.version: IdeaPad Flex 5 14ARE05
dmi.modalias: dmi:bvnLENOVO:bvrEECN20WW:bd04/08/2020:svnLENOVO:pn81X2:pvrIdeaPadFlex514ARE05:rvnLENOVO:rnLNVNB161216:rvrSDK0J40700WIN:cvnLENOVO:ct31:cvrIdeaPadFlex514ARE05:
dmi.product.family: IdeaPad Flex 5 14ARE05
dmi.product.name: 81X2
dmi.product.sku: LENOVO_MT_81X2_BU_idea_FM_IdeaPad Flex 5 14ARE05
dmi.product.version: IdeaPad Flex 5 14ARE05
dmi.sys.vendor: LENOVO
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.8-0ubuntu1~20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2.2
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+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[John Gilmore (gnu-gilmore)]

I found a way to enable the amdgpu support for this hardware in the standard LTS kernel! Based on this comment on a YouTube video reviewing this laptop:

  https://www.youtube.com/watch?v=FjegdWtHuOE&lc=UgzbtkQw4vuk6ls-6vF4AaABAg

Add "amdgpu.exp_hw_support=1" to the kernel command line in /etc/default/grub, run
update-grub, and reboot. This FIXES ALL THE ISSUES that I encountered in this bug. I am running linux-image-5.4.0-42-generic:amd64 (5.4.0-42.46) which is the current LTS kernel.

The same poster also recommended turning on this Firefox about:config setting, to avoid screen tearing while playing YouTube videos: layers.acceleration.force-enabled.

I have seen reports (comments below that same YouTube video, and elsewhere) that there are small kernel patches in the 5.7 kernels that also fix the screen brightness settings on this hardware. Perhaps a future Ubuntu kernel update can cherry-pick those fixes, and automatically enable the experimental hardware support for this integrated AMD Ryzen 5 4500U CPU/GPU? Would be good for these fixes to get into the Ubuntu 20.04.1 point release, too; these laptops are very fast and cost $600 so they are selling very well.

[Daniel van Vugt (vanvugt)]

John,

Thanks for figuring that out. Indeed it appears your hardware is a little too new for kernel 5.4 right now.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.