[DRM backend] Mouse look broken in Resident Evil 8

[tobiasjakobi]

Having an interesting problem with RE8 (Village) here. The mouse cursor appears in the game menu and works there, but any mouse look input when being in-game does not work.

Gamescope version is 3.15.5, but I'm also encountering the problem with 3.14.24 -- so if this is a regression, I'm not sure where it started.

Gamescope is running with the DRM backend. It is started by the greeter (greetd+gtk-greet) and then spawns the Steam client inside it's session. Any mouse grab options hence don't have any effect in this scenario.

Emulation layer is GE-Proton9-13, so pretty recent.

It seems plausible to me that this is a gamescope bug, for the following reason. When not using Gamescope the problem does not occur. In detail this means that instead of the Gamescope session I launch a Sway session from the greeter. From Sway I launch the Steam client, and from there the game. So XWayland is also involved here.

Not sure if it's important, but Sway is v1.9 and is using wlroots 0.17.4.

Looking for some input (no pun intended g) on how to debug this. I've already had a look at the code, but most of the stuff that relates to mouse input and that was touched recently involves nested modes, i.e. launching gamescope from another compositor and so on. So not applicable here...

Thanks in advance!

With best wishes,
Tobias

EDIT: I know that the RE engine is especially picky when it comes to additional input devices, i.e. if it detects a gamepad then it seems to ignore all mouse input. This is the first thing that crossed my mind, but it doesn't make sense here. When testing no gamepad was connected (neither wired nor wireless), and even if, why would it suddenly work when using Sway instead of Gamescope as compositor?