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[Neon] [Wayland] Getting memory corruption artifacts when running a fullscreen app at a high/native resolution (self.kde)

submitted 10 months ago* (last edited 10 months ago) by merthyr1831 to c/[email protected]

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I have a Lenovo 14aPH8 (Ideapad 5 gen 8?) which has a high DPI Screen with an AMD 7840HS (780m iGPU).

It's giving a bunch of memory corruption when on youtube in fullscreen, or before I reduce the resolution of a fullscreen application (Assetto Corsa Competizione is the only I've tried so far) from the native resolution to 1080p.

I previously RMA'd the Laptop due to similar artifacts on Pop!OS, and they confirmed the entire motherboard was replaced. However, the artifacts didn't go away so I tried KDE Neon which thankfully didn't have the same issues, until I tried gaming and youtube.On X11, the issues are gone, but as a fan of fractional scaling and touchscreen gestures I'm still using Wayland.

While this could be a hardware issue (I can't confirm as the laptop is so new not many people have it, let alone on linux) I'm sure this is software related because it only happens on X11, and I've also seem similar reports by nVidia users on Wayland.

Anyone able to signpost me if this isn't something KDE devs can investigate? I know a lot of them are active within the Wayland space so I thought asking here would be a good idea :)

EDIT: Looks like there's some upstream bug in the DRM with variable refresh rates and/or adaptive sync. Disabling it in KDE's settings seems to sort the problem in Youtube/games. Can't say the same for anyone else tho

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[–] [email protected] 2 points 10 months ago* (last edited 10 months ago) (1 children)

What do these artifacts look like? I've got lines appearing on my AMD laptop with fractional scaling enabled. But I'm pretty sure that my issue will be fixed in Plasma 6.

Edit: Actually for my issue I just increased my VRAM allocation to 4GB and it seems fine.

[–] merthyr1831 3 points 10 months ago (1 children)

For Youtube in fullscreen, it's small flashes of magenta pixels when the video controls appear/disappear (or when I move my mouse). For ACC, the screen goes white with moving elements outlined in black pixels until I set the resolution down to 1080p.

I actually get total screen corruption (multiple colours in stripes of corruption) when setting the screen resolution beyond native (eg. forcing wayland to downscale the image to my screen).

I'll check my VRAM allocation, right now I think it's 4GB but the BIOS is kinda limited -- hopefully I can get it to 6 or 8GB since I've got like 24GB of RAM to spare.

[–] [email protected] 1 points 10 months ago (2 children)

Yeah that's not normal, is there anything appearing in dmesg? Probably do dmesg | grep -i amdgpu to filter out the other stuff.

Otherwise maybe try a different desktop environment and create a bug report if it is KDE specific, or create one anyway and someone smarter than me should be able to work it out.

[–] merthyr1831 2 points 10 months ago

Gonna try Kubuntu for the hell of it, but just partitioned some space for Cinnamon and it doesn't have any of the issues at least in the X11 session (Updated the kernel too since Cinnamon likes to ship 5.15 which just barely works for this iGPU)

The Wayland session is janky af for Cinnamon anyway, but did notice that scrubbing a fullscreen YT video didn't really show any artifacting there. Then again, this could just be because their wayland implementation is very immature since most of the desktop was a blurry mess of jank.

[–] merthyr1831 2 points 10 months ago* (last edited 10 months ago)

Oooh maybe this is related, since my display is 144hz and turning the screen freq. to 96Hz stops the artifacting on Youtube... https://gitlab.freedesktop.org/drm/amd/-/issues/2967

Oh! Looks like adaptive sync might be the source. Disabled it and the artifacts disappear entirely. Set it to Always and the jank returns. Wahoo!

Gotta try in games to confirm

EDIT: Yup. ACC had less jank. I think VRR must be broken upstream (mentioned in that issue tracker)