Created attachment 127552 [details] [review]
Return earlier if not vdpau_driver

This issue was previously reported as
[Wayland] libvdpau fails on (X)Wayland, trying to load libvdpau_nvidia.so on non-nvidia systems
https://bugzilla.redhat.com/show_bug.cgi?id=1305699

Also note that there is no libvdpau Product in this bugzilla, I think it should be requested from the product owner to the freedesktop infra.

There is an issue with the way libvdpau tries (fails) to detect the appropriate backend if relevant:
1/ Under Xwayland. I have not tested myslef but according to the report, it should be possible to have vdpau acceleration under Xwayland (not native wayland even for gallium vdpau backends).
But the support is totally missing in libvdpau, so the default backend is tried (aka nvidia which for other reason doesn't work at all under current upstream XWayland).


2/ With recent Xorg-server (with DRI2 vdpau autodetection), it should be possible that there is no appropriate vdpau backend to choose and error with VDP_STATUS_NO_IMPLEMENTATION instead of trying nvidia and failing.

The problem with the attached patch is that it doesn't take the case where there is no DRI2 vdpau autodetection and defaulting to nvidia is better than nothing. (Hence the RFC tag).
The main benefit is that is will avoid a spurious message about nvidia, specially relevant when there is no nvidia hardware/driver at all.