I don't think we need to do like raw input in staging patches, I think X11 will be deprecated in a few years and staging patches cause regression, input doesn't work under wayland. My MR is enough to achieve the behavior of staging patches + xwayland.
Regardless of X11 and staging, if I understood @rbernon's comment correctly, the right approach would be to implement a proper upstream mechanism for the drivers to provide "raw" input events, and the Wayland driver can use the unaccelerated values in those events. Then games will behave properly because they will get the unaccelerated values in raw events (my understanding is that [3d] generally tend to use raw events, or can be configured to do so).
If we have proper raw events, the proposed option to make normal events unaccelerated would not be as compelling, correct?