I assume that you are using the self powered hub. For self powered HUB, VBUS monitoring is required because, HUB shouldn't drive data lines when VBUS is not connected or receiving less voltage. So whenever the VBUS goes low, reset is asserted.
Please explain your requirement in detail.
Controlling DSP power using VBUSPOWER is not a good idea. Pulling VBUSPOWER signal low will put the device into detached state.