IOCTL_POWER_SET Request Processing
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4/8/2010
Power Manager adjusts the power state of a device, using the IOCTL_POWER_SET device I/O control. Device driver developers should be aware of the following when implementing support for this I/O control:
- Power Manager can request that the device go into any device power state, not just the ones the device claims to support in its IOCTL_POWER_CAPABILITIES handler.
- If a device is requested to go into a power state it does not support, it is expected to go into the next higher-numbered state that it does support. For example, if a device does not support D2, it should go into D3 or D4 as appropriate. The D3 state requires some special handling.
- Power Manager can issue an IOCTL_POWER_SET that essentially puts the device into its already-current state. In this case, the device driver can return success and do nothing.
- Power Manager is not required to set the power state of a device to its default value as specified in a system power state. For example, if the power state of a device falls into the range bounded by the system power state and application requirements, Power Manager can choose not to alter the power state.
See Also
Reference
IOCTL_POWER_SET
IOCTL_POWER_CAPABILITIES