PoSetDeviceBusyEx function (wdm.h)
The PoSetDeviceBusyEx routine notifies the power manager that the device associated with the specified idle counter is busy.
Syntax
void PoSetDeviceBusyEx(
[in, out] PULONG IdlePointer
);
Parameters
[in, out] IdlePointer
A pointer to an idle counter. This is a pointer value that was previously returned by the PoRegisterDeviceForIdleDetection routine. Because PoRegisterDeviceForIdleDetection might return a NULL pointer, the caller must verify that the pointer is non-NULL before it calls PoSetDeviceBusyEx.
Return value
None
Remarks
This routine is a direct replacement for the PoSetDeviceBusy macro. If you are writing new driver code for Windows Vista with Service Pack 1 (SP1) and later versions of Windows, call PoSetDeviceBusyEx instead of PoSetDeviceBusy.
A driver calls the PoSetDeviceBusyEx and PoRegisterDeviceForIdleDetection routines to enable system idle detection for its device. If a device that is registered for idle detection stays idle for the driver-specified time-out period, the power manager sends an IRP_MN_SET_POWER request to put the device in a requested sleep state.
PoSetDeviceBusyEx reports that the device is busy, so that the power manager can restart its idle countdown. If the device is in a sleep state, PoSetDeviceBusyEx does not change the state of the device. That is, it does not cause the system to send an IRP_MN_SET_POWER request to awaken the device.
PoSetDeviceBusyEx is designed for use with I/O operations that are relatively brief compared to the time-out period of the idle counter. For longer operations that might exceed this period, use the PoStartDeviceBusy and PoEndDeviceBusy routines instead.
A driver that makes multiple requests for brief I/O operations should call PoSetDeviceBusyEx for every I/O request that it makes.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Available starting with Windows Vista with SP1. |
| Target Platform | Universal |
| Header | wdm.h (include Wdm.h, Ntddk.h, Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | Any level |