SW_DEVICE_CREATE_CALLBACK callback function

Provides a device with backing in the registry and allows the caller to then make calls to Software Device API functions with the hSwDevice handle.

Syntax

SW_DEVICE_CREATE_CALLBACK SwDeviceCreateCallback;

void SwDeviceCreateCallback(
  HSWDEVICE hSwDevice,
  HRESULT CreateResult,
  PVOID pContext,
  PCWSTR pszDeviceInstanceId
)
{...}

Parameters

hSwDevice

The handle for the software device.

CreateResult

An HRESULT that indicates if the enumeration of the software device was successful.

pContext

The context that was optionally supplied by the client app to SwDeviceCreate.

pszDeviceInstanceId

The device instance ID that PnP assigned to the device.

Return Value

None

Remarks

The operating system calls the SW_DEVICE_CREATE_CALLBACK callback function after PnP enumerates the device. After the callback function is called, the device has backing in the registry and calls to Software Device API functions can be made by using the hSwDevice handle. You can also use other APIs that work with devices for the device that is created.

PnP enumeration of a device is the first step that a device undergoes. After PnP enumeration of the device, the device only has registry backing, and you can set properties against the device. Just because PnP enumerated the device, the device hasn't started yet, and no driver for the device has registered or enabled interfaces yet. In many cases, we recommend that apps wait for device-interface arrival if they want to use the device.

Note  The callback function supplies the device instance ID for the created device. We recommend that callers of the Software Device API not try to guess at or construct the device instance ID themselves; always use the value provided by the callback function.
 
The callback function will execute on an arbitrary thread-pool thread. Client apps can perform as much work as needed in the callback function.

In Windows 8, you can't call SwDeviceClose inside the callback function. Doing so will cause a deadlock. Be careful of releasing a ref counted object that will call SwDeviceClose when its destructor runs. In Windows 8.1, this restriction is lifted, and you can call SwDeviceClose inside the callback function.

Always check the HRESULT that is passed to CreateResult to make sure PnP was able to enumerate the device.

Requirements

   
Minimum supported client Windows 8
Minimum supported server Windows Server 2012
Target Platform Desktop
Header swdevice.h

See Also

SwDeviceCreate