Bug 515784

Summary:	Direct scanout fails to activate for a certain game (Ray'z Arcade Chronology) when run using Proton-GE Wayland, but activates when using XWayland.
Product:	[Plasma] kwin	Reporter:	fbranemyr
Component:	compositing	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	NEEDSINFO WAITINGFORINFO
Severity:	normal	CC:	xaver.hugl
Priority:	NOR
Version First Reported In:	6.5.5
Target Milestone:	---
Platform:	EndeavourOS
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Screenshot of the game running in native Wayland. The white frame is not visible when viewed on the screen. Screenshot of the game running in XWayland. The white frame is visible even when viewed on the screen. Console output logged by launching with WAYLAND_DEBUG=1 PROTON_ENABLE_WAYLAND=1 %command% \|& tee /home/florian/Documents/log.txt

Description fbranemyr 2026-02-09 19:57:39 UTC

SUMMARY
This concerns the following game: https://store.steampowered.com/app/2478020/Rayz_Arcade_Chronology/

When this game is run in full screen using Proton-GE with no launch options, it activates direct scanout. However, when run using the launch option PROTON_ENABLE_WAYLAND=1, which causes Proton to use Wine Wayland, direct scanout is not activated, even though the game is in full screen.

STEPS TO REPRODUCE
1. Enable the show compositing effect from the kwin debug console.
2. Launch the game using Proton-GE without any launch options.
3. Observe that the red compositing text has disappeared, indicating direct scanout.
4. Launch the game using Proton-GE with the launch option PROTON_ENABLE_WAYLAND=1 %command%
5. Observe that compositing is still activated.

OBSERVED RESULT
Direct scanout does not activate in full screen.

EXPECTED RESULT
Direct scanout should activate when the game is in full screen.

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.1
Kernel Version: 6.18.6-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 12 × Intel® Core™ i5-10600K CPU @ 4.10GHz
Memory: 32 GiB of RAM (31.3 GiB usable)
Graphics Processor: AMD Radeon RX 6700

ADDITIONAL INFORMATION
I have attached a screenshot of the game running in native Wayland. What I noticed is that the screenshot shows white bars around the game. These are not visible when actually viewing the game on the screen. The fullscreen implementation is probably weird, but it still works in XWayland.

I am willing to do any sorts of tests to get to the bottom of the issue.

Comment 1 Zamundaaa 2026-02-09 21:24:38 UTC

The correlation between fullscreen and direct scanout isn't as direct as it might seem. Fullscreen windows just happen to usually cover the whole screen with a single opaque surface, but it's possible that they do more complicated things too.
The "white bars" sound like maybe the window isn't fully opaque, and/or is composed of multiple surfaces, which can prevent direct scanout from working.

(In reply to fbranemyr from comment #0)
> I have attached a screenshot of the game running in native Wayland. What I
> noticed is that the screenshot shows white bars around the game. These are
> not visible when actually viewing the game on the screen. The fullscreen
> implementation is probably weird, but it still works in XWayland.
I think you forgot to actually attach it.

Comment 2 fbranemyr 2026-02-10 08:13:23 UTC

Created attachment 189428 [details]
Screenshot of the game running in native Wayland. The white frame is not visible when viewed on the screen.

Comment 3 fbranemyr 2026-02-10 08:14:58 UTC

Created attachment 189429 [details]
Screenshot of the game running in XWayland. The white frame is visible even when viewed on the screen.

Comment 4 fbranemyr 2026-02-10 08:16:59 UTC

(In reply to Zamundaaa from comment #1)
> I think you forgot to actually attach it.

I've now attached screenshots of the game running in Wayland and XWayland. In Wayland it seems to have invisible white borders on all four sides, while in XWayland the borders are visible, but only exist on the top and left sides of the screen.

Is there any way to check if the game is using multiple or transparent surfaces?

Comment 5 Zamundaaa 2026-02-10 12:42:58 UTC

That kind of looks to me like the game is trying to do overscan compensation, and Proton's fullscreen hack for X11 makes it not work correctly.

(In reply to fbranemyr from comment #4)
> Is there any way to check if the game is using multiple or transparent
> surfaces?
If you run the game with WAYLAND_DEBUG=1 (just quit it again after it shows up fullscreen) and attach the output of that here, I can check.

Comment 6 fbranemyr 2026-02-10 18:06:22 UTC

Created attachment 189444 [details]
Console output logged by launching with WAYLAND_DEBUG=1 PROTON_ENABLE_WAYLAND=1 %command% |& tee /home/florian/Documents/log.txt

Comment 7 fbranemyr 2026-02-10 18:07:00 UTC

(In reply to Zamundaaa from comment #5)
> If you run the game with WAYLAND_DEBUG=1 (just quit it again after it shows
> up fullscreen) and attach the output of that here, I can check.

I've now added a debug log in the attachements.