What does this Driver does?

What does this Driver does? or it is useless?

Answer #1
It does what its name says – it’s the overall usb host controller – the others are subsets of the main controller, and the usb2 one is for usb2 (the others are usb1).
It’s like a marshalling yard for trains that sends out carriages to the sub-yards.
Answer #2
Fluffbutt replied:
It's like a marshalling yard for trains that sends out carriages to the sub-yards.
cool analogy
Answer #3
thanks for good explanation!