drm: Add vrr property helpers

[Drakulix]

Draft while this is missing docs and more testing.

Adds helper methods to make it possible to set VRR per frame, which makes more dynamic VRR policies like "only enable, when we have a fullscreen application" more easily possible. Also simplifies VRR checks.

[Drakulix]

Now in use here and seems to work well: pop-os/cosmic-comp#1004

[cmeissl]

wp_presentation version 1 requires 0 to be sent for vrr

If the output does not have a constant refresh rate, explicit video mode switches excluded, then the refresh argument must be zero.

[Drakulix]

@cmeissl I pushed new (separate) commits to make review easier (though I actually plan to merge most of them).

I hope the DrmCompositor cursor skip is now correct.

And I added an example to anvil for sending the right PresentationTime refresh rate, though I would prefer to drop that commit given anvil doesn't implement VRR at all. It is just there to show off how easy this is to do with the vrr_enabled-method. I thought about adding it to the FrameResult (as we only really know the refresh rate mode we send off to the hardware on submit, but making the into a proper struct with meta data felt overkill, when the check is this simple.

[cmeissl]

We should keep cursor only updates in case we have re-drawn the plane or otherwise we would loose the rather costly rendering step we already did. This would also result in constant re-drawing of the plane until we do not skip it.

[cmeissl]

And I added an example to anvil for sending the right PresentationTime refresh rate, though I would prefer to drop that commit given anvil doesn't implement VRR at all. It is just there to show off how easy this is to do with the vrr_enabled-method. I thought about adding it to the FrameResult (as we only really know the refresh rate mode we send off to the hardware on submit, but making the into a proper struct with meta data felt overkill, when the check is this simple.

Looks goods and I agree that we can remove that from anvil as it does not support vrr at all. I hope that the breaking change for the refresh parameter is enough to get people implement it correctly.

[Drakulix]

@cmeissl Merged your changes, removed self.vrr, dropped the anvil commit and squashed. Ready for merge?

[cmeissl]

@cmeissl Merged your changes, removed self.vrr, dropped the anvil commit and squashed. Ready for merge?

Yes :)

[Drakulix]

@cmeissl Merged your changes, removed self.vrr, dropped the anvil commit and squashed. Ready for merge?

Yes :)

Thanks! :)