The hub driver creates a PDO for the joystick device and includes a referenced pointer to the joystick PDO in its list of child devices returned with the IRP. In this example, the USB hub driver handles this IRP for the hub FDO. See the reference page for IRP_MN_QUERY_DEVICE_RELATIONS for detailed information about handling this IRP. The function driver for the bus device handles the IRP. According to the rules for PnP IRPs, each driver in the stack handles the IRP, if appropriate, and passes the IRP down to the next driver. The PnP manager sends the IRP to the top driver in the device stack for the bus. The value is BusRelations, indicating that the PnP manager is asking for the current list of devices present on the bus ( bus relations). The PnP manager sends an IRP_MN_QUERY_DEVICE_RELATIONS request to the device stack for the bus. The PnP manager queries the bus's drivers for the current list of devices on the bus. The function driver notifies the PnP manager by calling IoInvalidateDeviceRelations with a Type of BusRelations. The function driver for the bus device notifies the PnP manager that its set of child devices has changed.

In this example, the USB bus supports hot-plug notification so the function driver for the USB bus is notified that its children have changed. If the bus does not support hot-plug notification, the user must take appropriate action in Control Panel to cause the bus to be enumerated. For some buses, the bus function driver receives hot-plug notification of new devices. How the driver determines this depends on the bus architecture. The function driver for the bus device determines that a new device is on its bus. The USB hub is a PnP bus device because child devices can be attached to it. In this example, the user plugs a PnP USB joystick into the hub on a USB host controller. The following notes correspond to the circled numbers in the previous figure:Ī user plugs a PnP device into a free slot on a PnP bus.

The following figure shows the first steps in configuring the device, starting from when the user plugs the hardware into the machine.

Specifically, devices whose drivers are marked SERVICE_DEMAND_START in an INF file are configured in essentially the same way whether the device is added dynamically or is present at boot time. Most of this discussion is also relevant to configuring a PnP device that is present when the machine is booted. This discussion highlights the roles of the PnP manager, bus drivers, and function and filter drivers in enumerating and configuring a new device. This section describes the sequence of events that occur when the system configures a PnP device that a user has added to a running machine.

Pnp windows 10