IWDFUsbTargetDevice::RetrievePowerPolicy method

[Warning: UMDF 2 is the latest version of UMDF and supersedes UMDF 1. All new UMDF drivers should be written using UMDF 2. No new features are being added to UMDF 1 and there is limited support for UMDF 1 on newer versions of Windows 10. Universal Windows drivers must use UMDF 2. For more info, see Getting Started with UMDF.]

The RetrievePowerPolicy method retrieves a WinUsb power policy.

Syntax

HRESULT RetrievePowerPolicy(
  ULONG PolicyType,
  ULONG *ValueLength,
  PVOID Value
);

Parameters

PolicyType

The type of WinUsb power policy that the UMDF driver requests.

ValueLength

A pointer to a variable that, on input, contains the size, in bytes, of the buffer that RetrievePowerPolicy supplies in Value. On output, this parameter contains the size that RetrievePowerPolicy requires for Value.

Value

A pointer that receives the buffer that contains the WinUsb power policy.

Return Value

RetrievePowerPolicy returns one of the following values:

Return code Description
S_OK
RetrievePowerPolicy successfully retrieved the WinUsb power policy.
E_OUTOFMEMORY
RetrievePowerPolicy encountered an allocation failure.
An error code that is defined in Winerror.h
This value corresponds to the error code that the WinUsb API returned.

Remarks

Power policy controls the power management that WinUsb for the device performs.

For information about valid policy types that a UMDF driver can pass for the PolicyType parameter and values that the framework returns, see the WinUsb_GetPowerPolicy function.

For more information about the power behavior of WinUSB, see WinUSB Power Management.

The RetrievePowerPolicy method generates a UMDF request and synchronously sends the request to the I/O target.

Requirements

   
End of support Unavailable in UMDF 2.0 and later.
Target Platform Desktop
Minimum UMDF version 1.5
Header wudfusb.h (include Wudfusb.h)
DLL WUDFx.dll

See Also

IWDFUsbTargetDevice

IWDFUsbTargetDevice::SetPowerPolicy

WinUsb_GetPowerPolicy