Detecting Child Devices

You must implement HwVidGetVideoChildDescriptor in your miniport driver for the Plug and Play manager to be able to detect child devices of a graphics adapter.

By default, HwVidGetVideoChildDescriptor cannot be called until after the parent device is started; that is, HwVidGetVideoChildDescriptor cannot be called until after HwVidFindAdapter has completed. To override this default, thus allowing child enumeration to occur at any time, you can set the AllowEarlyEnumeration member of VIDEO_HW_INITIALIZATION_DATA to TRUE.

Some devices generate an interrupt when new hardware is connected to the system or when existing hardware is disconnected from the system. To handle such an interrupt, the miniport driver should do the following:

• Implement a DPC (HwVidDpcRoutine) that calls VideoPortEnumerateChildren.

• Implement an interrupt handler (HwVidInterrupt) that calls VideoPortQueueDpc to queue the DPC when an interrupt on the device occurs.

VideoPortEnumerateChildren forces the reenumeration of the adapter's child devices by causing the miniport driver's HwVidGetVideoChildDescriptor function to be called for each of the parent device's children. The Plug and Play manager will update the relationship between the parent device and its children accordingly.