/** * i915_switch_context() - perform a GPU context switch. * @ring: ring for which we'll execute the context switch * @to: the context to switch to * * The context life cycle is simple. The context refcount is incremented and * decremented by 1 and create and destroy. If the context is in use by the GPU, * it will have a refoucnt > 1. This allows us to destroy the context abstract * object while letting the normal object tracking destroy the backing BO. */