| Summary: | Direct Scanout not working on DGPU (Radeon + Nvidia) | ||
|---|---|---|---|
| Product: | [Plasma] kwin | Reporter: | Syntist <syed.talha.khalid> |
| Component: | compositing | Assignee: | KWin default assignee <kwin-bugs-null> |
| Status: | RESOLVED UPSTREAM | ||
| Severity: | normal | CC: | enesaltinkaya, nicolas.fella, syed.talha.khalid, xaver.hugl |
| Priority: | NOR | Flags: | syed.talha.khalid:
Mesa+
syed.talha.khalid: NVIDIA+ |
| Version First Reported In: | 6.4.4 | ||
| Target Milestone: | --- | ||
| Platform: | Other | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed In: | ||
| Sentry Crash Report: | |||
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Description
Syntist
2025-08-15 19:58:25 UTC
Not working for me either. https://youtu.be/MXVbSsszIa4 https://imgur.com/a/Y6xAfkA Operating System: Arch Linux KDE Plasma Version: 6.4.4 KDE Frameworks Version: 6.17.0 Qt Version: 6.9.1 Kernel Version: 6.16.1-arch1-1 (64-bit) Graphics Platform: Wayland Processors: 32 × AMD Ryzen 9 5950X 16-Core Processor Memory: 48 GiB of RAM (47.0 GiB usable) Graphics Processor: NVIDIA GeForce RTX 5090 I noticed if the game doesn't use a cursor, Compositing text dissapear. If the game has a "hardware cursor" setting and it is disabled Compositing text dissapear. World of Warcraft and Witcher 3 has that option. But... even when the Compositing text goes away, there is still input lag and there is no screen tear. Vsync is off and fps is capped at 60 by DXVK_FRAME_RATE env variable, there should be screen tear. Or maybe direct scanout and allow tear are not related? I also noticed that if Color profile in display settings is not None, Compositing text never goes away. I tried everything, it just doesn't work when I run the game using dgpu (nvidia), not sure why it does that. On my other laptop which has IGPU (intel) it works fine, when i run the game on dgpu (nvidia) Something with AMD + Nvidia. Wish someone could check this issue out. I have tried Forcing SW Cursor and same issue, I think it's related to driver, because even on gnome when the game is being run on nvidia (offloading) it doesn't go in direct scanout mode, just like in kde. But would be great if there's any update on it. I noticed, if there is a rule forcing "Allow tearing" direct scanout doesnt work 🤷♂️ At 30th second in the video i sent in my first post, i had that rule as well, removing it makes direct scanout work. But I couldnt see any improvement over input delay in games, vsync is still forced on, tear never worked for me. (In reply to Enes from comment #5) > I noticed, if there is a rule forcing "Allow tearing" direct scanout doesnt > work 🤷♂️ > At 30th second in the video i sent in my first post, i had that rule as > well, removing it makes direct scanout work. > > But I couldnt see any improvement over input delay in games, vsync is still > forced on, tear never worked for me. Your issue is different then mine, you are on a desktop with one GPU (nvidia) while mine is laptop and it has igpu and dgpu, nvidia-offloading is being used, and that's why Direct scanout is not working, but works fine if i run the game on igpu. (In reply to Syntist from comment #6) > (In reply to Enes from comment #5) > > I noticed, if there is a rule forcing "Allow tearing" direct scanout doesnt > > work 🤷♂️ > > At 30th second in the video i sent in my first post, i had that rule as > > well, removing it makes direct scanout work. > > > > But I couldnt see any improvement over input delay in games, vsync is still > > forced on, tear never worked for me. > > Your issue is different then mine, you are on a desktop with one GPU > (nvidia) while mine is laptop and it has igpu and dgpu, nvidia-offloading is > being used, and that's why Direct scanout is not working, but works fine if > i run the game on igpu. I see, sorry for the confusion. sad no news on this :( I think it's related to AMD Driver maybe. Direct scanout is an optional optimization that simply doesn't always work. One GPU being able to (efficiently) do direct scanout from another GPU would be a rare thing, not something you can expect. More specifically in this case however, the NVidia driver almost certainly already does a copy from the dGPU to the integrated one, and it would need to allocate these buffers on the integrated GPU in a way that they're suitable for scanout. You can report that not working at https://forums.developer.nvidia.com/c/gpu-graphics/linux (In reply to Enes from comment #2) > Or maybe direct scanout and allow tear are not related? They're pretty much completely unrelated. (In reply to Zamundaaa from comment #9) > Direct scanout is an optional optimization that simply doesn't always work. > One GPU being able to (efficiently) do direct scanout from another GPU would > be a rare thing, not something you can expect. > > More specifically in this case however, the NVidia driver almost certainly > already does a copy from the dGPU to the integrated one, and it would need > to allocate these buffers on the integrated GPU in a way that they're > suitable for scanout. You can report that not working at > https://forums.developer.nvidia.com/c/gpu-graphics/linux > > (In reply to Enes from comment #2) > > Or maybe direct scanout and allow tear are not related? > They're pretty much completely unrelated. Okay, although It does work on the laptop with Intel iGPU and Nvidia dGPU, but just doesn't work with Radeon iGPU and Nvidia dGPU combo. Intel + Nvidia (works) Radeon + Nvidia (doesn't work) I'll make a report on nvidia forum related this. |