device_add_child_ordered to add the child. device_add_child_ordered
doesn't call BUS_ADD_CHILD.
* For busses which use use drivers supporting DEVICE_IDENTIFY() to
* enumerate their devices, this method is used to create new
* device instances. The new device will be added after the last
- * existing child with the same order.
+ * existing child with the same order. Implementations of bus_add_child
+ * call device_add_child_ordered to add the child and often add
+ * a suitable ivar to the device specific to that bus.
*
* @param _dev the bus device which will be the parent of the
* new child device