Comment 0 for bug 1519623

USB core expects the roothubs to support the same requests and descriptors as external hubs. As the two roothubs (USB2 and USB3) are
part of xhci we need to support the descriptor and request changes in USB3.1. In our case we need to:
1)Fill and return the new SuperSpeedPlus USB Device capability descriptor as part of the BOS (Binary device Object Store) descritptor. The speed info needed to fill this descriptor can be parsed from extended capability, supported protocol PSI lists. (see xhci 1.1 section 7.2)
2)Return the new EXT_PORT_STATUS when usb core requests a get_port_status() with new option. Can be read from xhci PORTSC register speed field, and map it to the PSI in the extended capability.Optionally check it from slot output context?
3) Check if usb core stored SSP (SuperSpeedPlus) isoc endpoint companion data with the endpoint and use it to calculate max packets and bandwidth.

Upstream:
kernel:TBD