BACKENDS: SDL: Lower mouse sensitivity / slower cursor in SDL Wayland mode in Conquests of the Longbow

[shmerl]

When playing Conquests of the Longbow using SDL in Wayland mode (SDL_VIDEODRIVER=wayland), the cursor is noticeably slower (or mouse has lower sensitivity?) than when playing it with SDL in x11 mode.

Set up:

• KDE Plasma / kwin 5.27.5 in Wayland session.
• scummvm: 2.7.0
• libsdl2: 2.26.5

Not sure if it's an SDL issue or not. If it is, I can open the bug upstream. Or may be it's a matter of some configuration mismatch?

[lotharsm]

Could you check if this happens on other games/engines as well?

At first glance, this sounds more like an SDL issue to me, but I want to be sure :-)

[shmerl]

I tried Indiana Jones and the Fate of Atlantis and it doesn't have such issue.

A few observations when using MangoHUD to monitor things:

• My display has adaptive sync (variable refresh rate), with 180 Hz max. Adaptive sync is active in the compositor.
• Indiana Jones and the Fate of Atlantis runs at around 10 fps normally and at around 100 fps when I move the cursor quickly back and forth. Behavior is the same in Wayland and X11 SDL mode.
• Conquests of the Longbow runs at ~34 fps normally and when moving cursor fast - at 50 fps (both in X11 and Wayland SDL mode). But when in Wayland mode, cursor feels more sluggish.

My guess is, that Indiana Jones having higher framerate when cursor moves mitigates this issue on Wayland, while Conquests of the Longbow being somehow capped at 50 fps hits a problem there, that isn't present in X11 mode.

[shmerl]

Oh, and for the reference:

GPU: AMD Sapphire Nitro+ 7900 XTX, using Mesa main.

[sev-]

Unfortunately, this looks like an SDL issue. We do not do anything special for Wayland and fully rely on the SDL for mouse events. I hope it is fixed or will be fixed upstream