Method and apparatus for managing power in computer systems

Abstract

The invention is directed towards minimizing power consumption in computer systems. One embodiment of the invention is a power management system that is used for a computer system that has at least one device and one power domain. This embodiment uses two different power managers to manage the power consumption of the device and the power domain. Specifically, this embodiment has (1) a first power manager that determines when to change power state of the device, and (2) a second power manager that determines when to change power state of the power domain. Each of these power managers decides to change the power state of its corresponding device or domain based on information from several different sources. These sources can include power-management clients and power managers of related domains or devices.

What is claimed is: 
     
         1 . A system, comprising:
 a first member device;   a second member device; and   a root device, comprising:
 a processor; and 
 a memory configured to store instructions that when executed by the processor cause the root device to perform steps that include:
 receiving an idle status signal from the first member device; 
 automatically sending a sleep command to the second member device in response to receiving the idle status signal, wherein the sleep command causes the second member device to enter a first power state; 
 receiving an active status signal from the first member device; and 
 automatically sending a wake command to the second member device in response to receiving the active status signal, wherein the wake command causes the second member device to transition into a second power state.