WDM设备电源状态

WDM的电源状态包括设备电源状态和系统电源状态。在头文件中分别定义如下：

设备电源状态

typedef enum _DEVICE_POWER_STATE {
    PowerDeviceUnspecified = 0,
    PowerDeviceD0,
    PowerDeviceD1,
    PowerDeviceD2,
    PowerDeviceD3,
    PowerDeviceMaximum
} DEVICE_POWER_STATE, *PDEVICE_POWER_STATE;

系统电源状态

typedef enum _SYSTEM_POWER_STATE {
    PowerSystemUnspecified = 0,
    PowerSystemWorking     = 1,
    PowerSystemSleeping1   = 2,
    PowerSystemSleeping2   = 3,
    PowerSystemSleeping3   = 4,
    PowerSystemHibernate   = 5,
    PowerSystemShutdown    = 6,
    PowerSystemMaximum     = 7
} SYSTEM_POWER_STATE, *PSYSTEM_POWER_STATE;

电源状态的初始化

一个设备FDO在创建后，应在其扩展单元结构体中随时跟踪记录设备和系统的电源状态，以实现不同的设备状态转换。
但设备在初始化时即AddDevice中IoCreateDevice后，电源状态应初始化：

    pdx->DevicePowerState = PowerDeviceUnspecified;
    pdx->SystemPowerState = PowerSystemWorking;