US Patent 7885282 Dynamic control of physical layer quality on a serial bus

A control system controls a physical layer quality of user data transmitted between first and second ends of a serial bus. The control system comprises a first line driver that has a control input that controls the physical layer quality at the first end. A physical layer quality sensor senses the physical layer quality at the second end and generates control primitives that are fed back over the serial bus to the control input to provide closed loop control of the physical layer quality.