USB establish communication between devices and a host controller.It connects computer peripherals such as mouse, keyboards, digital cameras, printers, personal media players, flash drives, Network Adapters, and external hard drives.
The original USB 1.0 specification had a data transfer rate of 12 Mbit/s.USB 2.0 had a data transfer rate of 480 Mbit/s.USB 3.0 is a newly launched and has a specification of 4.8 Gbps.USB.It promises increased maximum bus power and increased device current draw to better accommodate power-hungry devices,New power management features and full-duplex data transfers and support for new transfer types.
Fedora 14 includes the support of USB 3.0 but by default it comes disabled. Reason being it is preventing users from being able to suspend their laptops. USB 2.0 ports (ehci_hcd) works fine as expected.
For anyone who need support for USB 3.0 and support for suspend/resume is not necessary, there is a workaround. Just pass the kernel parameter
This allows the xHCI support to load. There is also a workaround which will allow you to enable USB 3.0 support and still suspend successfully.
Next,create a file named /etc/pm/config.d/xhci, with the contents:
One can suspend and resume the system successfully.
Hope it helps !!!