Patent ID: 8286014
Filing Date: 2012-10-09
Classification: G06F,Y02D

Abstract:
1. A method comprising: sending a first link handshake signal between a first subsystem and a power management unit (PMU) of a system on a chip (SoC) on a sideband channel coupled between the first subsystem and the PMU, the first link handshake signal to request entry into a power saving state for the first subsystem in which the first subsystem is in a first device power state and appears to an operating system (OS) as being in a second device power state different than the first device power state, the power saving state between consecutive device power states of an OS-driven power management system; sending a second link handshake signal between the first subsystem and the PMU to acknowledge the request; and placing the first subsystem into the power saving state in response to the second link handshake signal without further signaling between the power management unit and the first subsystem.