Robust computer subsystem power management with or without explicit operating system support

Abstract

Methods and devices for power management of graphics or other computer subsystems are disclosed. In one embodiment, graphics software components are configurable in a manner that allows them to place the graphics subsystem is a 'safe' state prior to a suspend event, and back into a 'working' state after a resume event, without explicit support from an operating system (OS) power management driver. When operating in the absence of an OS-supplied driver, the graphics driver receives notification of power management events, and sends a message to a support application, which then causes the graphics to enter a quiescent state by taking exclusive ownership of the display and issuing standard device-independent OS graphics calls (for a power-down event) or to relinquish display ownership (for a power-up event). From within this quiescent state the graphics may be safely power managed without adverse effects to the graphics chips and without creating any instabilities in other graphics applications. These graphics software components detect the level of power management provided by the OS during system initialization, and self-configure such that an appropriate graphics power management scheme is in place for whatever level of power management is supplied—or not supplied—by the operating system.