A multi-core data processor includes multiple data processor cores and a circuit. The multiple data processor cores each include a power state controller having a first input for receiving an idle signal, a second input for receiving a release signal, a third input for receiving a control signal, and an output for providing a current power state. In response to the idle signal, the power state controller causes a corresponding data processor core to enter an idle state. In response to the release signal, the power state controller changes the current power state from the idle state to an active state in dependence on the control signal. The circuit is coupled to each of the multiple data processor cores for providing the control signal in response to current power states in the multiple data processor cores.