A system capable of bi-directional data transfer, the system including a host configured to send downstream data to a peripheral and to receive upstream data from the peripheral, a main link coupled to the host and configured to transfer the downstream data from the host to the peripheral, and an auxiliary link coupled to the host and including a first auxiliary link lane for transferring the upstream data from the peripheral to the host in a first mode, and for transferring the downstream data from the host to the peripheral in a second mode, wherein the host is configured to engage in one or more handshake processes with the peripheral to cause the auxiliary link to switch between the first and second modes.