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DxgkDdiSetPowerState routine

The DxgkDdiSetPowerState function sets the power state of a display adapter or a child device of a display adapter.

Syntax


PDXGKDDI_SET_POWER_STATE DxgkDdiSetPowerState;

NTSTATUS DxgkDdiSetPowerState(
  _In_  const PVOID MiniportDeviceContext,
  _In_  ULONG DeviceUid,
  _In_  DEVICE_POWER_STATE DevicePowerState,
  _In_  POWER_ACTION ActionType
)
{ ... }

Parameters

MiniportDeviceContext [in]

A handle to a context block associated with a display adapter. The display miniport driver's DxgkDdiAddDevice function previously provided this handle to the DirectX graphics kernel subsystem.

DeviceUid [in]

A positive integer that identifies the device for which the power state is to be set. If DeviceUid is equal to DISPLAY_ADAPTER_HW_ID (defined in Video.h), the device is the display adapter itself. Otherwise, DeviceUid is the identifier of a child device of the display adapter. Child device identifiers were previously assigned by the DxgkDdiQueryChildRelations function.

DevicePowerState [in]

A DEVICE_POWER_STATE enumeration value that supplies the power state (PowerDeviceD0, PowerDeviceD1, PowerDeviceD2, PowerDeviceD3) to which the device should be set.

ActionType [in]

A POWER_ACTION enumeration value that supplies the reason (PowerActionSleep, PowerActionHibernate, PowerActionShutdown) for the power state change.

Return value

DxgkDdiSetPowerState returns STATUS_SUCCESS if it succeeds. DxgkDdiSetPowerState should never fail; however, it can return any NTSTATUS-typed value that is defined in Ntstatus.h and that passes the NT_SUCCESS(Status) macro.

Remarks

If the requested state is equal to PowerDeviceD1, PowerDeviceD2, or PowerDeviceD3, DxgkDdiSetPowerState saves any context that will later be required to bring the device back to PowerDeviceD0 and then places the device in the requested state. If the requested state is PowerDeviceD0 (fully on), DxgkDdiSetPowerState restores the device context and places the device in PowerDeviceD0.

If DxgkDdiSetPowerState is called with a request to put the VGA-enabled display adapter into hibernation, it should not power down the display adapter. Instead, it should save the context and let the bus driver power down the display adapter. That way, the power manager can display hibernation progress after the display miniport driver has been notified about the power state change.

The operating system might call DxgkDdiSetPowerState on a child device of the display adapter that is no longer connected (for example, a monitor that was recently unplugged). This anomaly occurs because an inherent latency exists between the time that the operating system calls the driver's DxgkDdiSetPowerState and the time that the operating system processes the disconnection. The driver must handle such situations without failing.

If DevicePowerState is equal to PowerDeviceD0, do not rely on the value of ActionType.

Starting with Windows Display Driver Model (WDDM) 1.2, if the DevicePowerState parameter is set to PowerDeviceD0, the display miniport driver should call DxgkCbAcquirePostDisplayOwnership to query the information about the display mode. This display mode might have been been previously set by the firmware and system loader. If DxgkCbAcquirePostDisplayOwnership returns with STATUS_SUCCESS, the driver should determine whether it has to reinitialize the display based on the display mode information that was returned through the DisplayInfo parameter. Otherwise, the driver should not assume that any specific display mode is currently enabled on the device, and it should initialize the display.

The DxgkDdiSetPowerState function should be made pageable.

Requirements

Version

Available starting with Windows Vista.

Header

Dispmprt.h (include Dispmprt.h)

IRQL

PASSIVE_LEVEL

See also

DxgkCbAcquirePostDisplayOwnership
DxgkDdiAddDevice
DxgkDdiQueryChildRelations

 

 

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