PCAM_STATE_ROUTINE callback function (usbcamdi.h)

Article
02/22/2024

[CamRestoreState is not supported and may be altered or unavailable in the future. ]

A camera minidriver's state callback function restores a previously saved device context state or saves the current device context state.

Syntax

PCAM_STATE_ROUTINE PcamStateRoutine;

NTSTATUS PcamStateRoutine(
  PDEVICE_OBJECT BusDeviceObject,
  PVOID DeviceContext
)
{...}

Parameters

BusDeviceObject

Pointer to the camera minidriver's device object created by the USB hub.

For CamSaveState, this value can be NULL.

DeviceContext

Pointer to the camera minidriver's device context.

Return value

This callback routine must return STATUS_SUCCESS.

Remarks

About CamRestoreState

USBCAMD calls the minidriver's CamRestoreState callback function in the context of an SRB_CHANGE_POWER_STATE request when the power state is going from OFF to ON (D3 to D0).

USBCAMD ignores the return value from the minidriver's CamRestoreState.

CamRestoreState is called by both versions 1.0 and 2.0 of USBCAMD.

This function is optional.

About CamSaveState

USBCAMD version 1.0 calls the minidriver's CamSaveState in the context of an SRB_CHANGE_POWER_STATE request where the power state is going from ON to OFF (D0 to D3).

USBCAMD ignores the return value from the minidriver's CamSaveState callback function.

CamSaveState is called by both versions 1.0 and 2.0 of USBCAMD.

This function is optional.

Requirements

Requirement	Value
Minimum supported client	Available on Windows operating system versions prior to Windows XP.
Target Platform	Desktop
Header	usbcamdi.h (include Usbcamdi.h)