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stacking_consistent

drmkit_planes

Function stacking_consistent 

Source 
pub fn stacking_consistent(
    pa: &PlaneCapabilities,
    za: Option<u64>,
    pb: &PlaneCapabilities,
    zb: Option<u64>,
) -> bool
Expand description

Whether layer A (zpos za) on pa and layer B (zpos zb) on pb stack in the order their zpos values request.

Layers without a zpos, or with equal ones, request no order. Different requests landing on the same effective slot are ambiguous – the kernel breaks the tie by plane id – and rejected. On mutable planes the effective zpos is the requested one, so this only ever rules on fixed-slot planes.