![]() Wake can occur when the user hits a key on the keyboard, presses the power button, or when the computer receives a network administrator wake-up packet. The important thing to understand about a sleep event is that your device may be powered off when the system sleeps, so your driver must be prepared to initialize the device when it is awakened.Īll drivers must respond to a system wake event by powering on. To your driver, however, all sleep events appear identical. For example, system sleep occurs when the user chooses Sleep from the Apple menu or closes the lid of a laptop idle sleep occurs when there has been no device or system activity during the interval the user selects in the Energy Saver preferences. OS X defines different types of sleep, which can occur for different reasons. ![]() In OS X, power events are transitions to and from the following states:Īll drivers must respond to sleep events. After you decide what type of power management you need to implement, read Implementing Basic Power Management and, if appropriate, Implementing Advanced Power Managementīefore you consider how to implement power management in your driver, you need to understand what power events are and how they can affect your device. Then, all driver developers should read Deciding How to Implement Power Management in Your Driver to find out what to do next. The Power Plane: A Hierarchy of Power Dependencies which describes how OS X monitors the power relationships among devices, drivers, and other objectsĭevices and Power States which defines devices and power states in power-management terms ![]() Power Events which explains what power events are and how they affect your device If you’re unfamiliar with power management in OS X, you should begin by reading the following three sections: The precise set of power-management responsibilities your driver must fulfill depends on factors such as how much support your driver’s superclass provides, whether your device receives power from a system bus (such as PCI), and to what power events your driver needs to respond. For more information on developing applications that behave as user-space drivers, including information on how to set up your application to receive power-event notifications, see Accessing Hardware From Applications. Note: If you’re developing an application that accesses hardware, such as a user-space driver for a digital camera, scanner, webcam, or tape drive, you probably do not need to perform any power-management tasks.
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