IOCTL_VIDEO_VALIDATE_CHILD_STATE_CONFIGURATION control code
Queries the miniport driver to determine whether it is ready for a display device switch. This switch is a state change in which the video signal going to one display device is sent to another, possibly different type of display device. After the display device switch, the video signal can be sent to one or both display devices. When the video port driver receives a request to switch display devices (by, for example, a hotkey being pressed), it sends this IOCTL to the video miniport driver. The value returned by the miniport driver indicates whether the video port driver should proceed with the display device switch.
When the miniport driver receives this request, it should indicate that it has successfully handled the request by:
Placing the appropriate value (described in the Output section) in OutputBuffer
Returning NO_ERROR in the Status member of the VRP's StatusBlock
The video miniport driver carries out a validated display device switch when it receives an IOCTL_VIDEO_SET_CHILD_STATE_CONFIGURATION request.
The miniport driver is not required to handle this modal IOCTL. The video port driver interprets a default return value from the miniport driver as permission to proceed with the display device switch.
The VRP InputBuffer contains a VIDEO_CHILD_STATE_CONFIGURATION structure.
The miniport driver returns 1 in the VRP OutputBuffer if the video port driver should proceed with the display device switch; otherwise, the driver returns 0 in the VRP OutputBuffer.
The miniport driver stores NO_ERROR in Status if it has successfully handled this IOCTL; otherwise, the driver stores a relevant video error code in Status. In either case, the miniport driver sets the Information member of the STATUS_BLOCK structure to sizeof(ULONG).