Vulkan video driver makes direct scanout not work on KDE Wayland.

Is there an existing issue for this?

• This is a bug in RetroArch frontend
• I have searched the existing issues

Description

On Linux, when the video driver is set to vulkan, direct scanout does not work on KDE Wayland. Direct scanout lowers video latency by bypassing the compositor, so it is desirable to have.

Expected behavior

Direct scanout should activate as it does when using the gl driver.

Steps to reproduce the bug

1. Activate the "show compositing" effect in the kwin debug console, which can be opened using the command "qdbus org.kde.KWin /KWin showDebugConsole". It displays red text in the top right corner when compositing is active.
2. Launch Retroarch in full screen using the gl driver.
3. Observe that the red text disappears, indicating that direct scanout has been activated.
4. Change the video driver to vulkan. Close Retroarch and reopen it.
5. Observe that the red text is still there, indicating that direct scanout is not activated.

Version/Commit

1.22.2 (Git 502c425)

Bisect Results

No response

Present in the nightly version

Yes, this is reproduced in the nightly build

Platform & operating system

Linux EndeavourOS x86_64

Affected Cores

No response

Environment information

• Window Manager: Wayland
• Installed through AppImage

Relevant log output

Reproduce the issue on Linux with KDE Wayland using the listed qdbus KWin debug-console command, comparing fullscreen GL and Vulkan runs. Trace the frontend's Vulkan and GL fullscreen paths; done means Vulkan also activates direct scanout, shown by the compositing indicator disappearing.