Common idle state, active state and credit management for an interface

An apparatus comprising:

• a fabric coupled to each of a plurality of agents via an interface having a fabric arbiter and a plurality of queues each associated with a corresponding queue of the agent, the fabric further including a fabric idle state machine (ISM) including a first set of states, wherein the fabric ISM is to transition between selected ones of the first set of states according to first state transitions to perform credit management, active mode management, and idle state management;
• and
• the plurality of agents coupled to the fabric, each of the plurality of agents having an interface including a request put arbiter, a plurality of queues, and a plurality of credit trackers each to track credits for one of the queues of the corresponding fabric interface, and further including an agent ISM including a second set of states, wherein the agent ISM is to transition between selected ones of the second set of states according to second state transitions to perform credit management, active mode management, and idle state management, via a handshake protocol with the fabric ISM, wherein the first and second sets of states and the first and second state transitions are different.