Selective suspension of bus devices

A method and system for asserting power control over one or more hardware devices connected via a bus. The invention includes a method and system for signaling and waiting to suspend a first device connected to a second device. The invention also includes a method and system for suspending a tree of devices with one or more of the devices hierarchically organized as parent devices and child devices in the tree. A controller at a root of the tree receives an idle request from one or more of the child devices and suspends all devices in the tree after receiving an idle request from each of the child devices. The invention also includes an input/output control (IOCTL) data structure for communicating the idle request.