What to do with unused I/O pins for TUSB7340 ?

Hi,

I am using TUSB7340 in my board. I need only three usb ports. So I would like to know do I have to use a pull down for unused USB_DM,USB_DP, USB_SSRXP and USB_SSRXN pins or it can be left open.

Thanks & Regards,

Manisha