LS_DOWN
linkState = LS_DOWN;
qdev->port_link_state = LS_DOWN;
case LS_DOWN:
if (curr_link_state == LS_DOWN) {
qdev->port_link_state = LS_DOWN;
qdev->port_link_state = LS_DOWN;
qdev->port_link_state = LS_DOWN;
qdev->port_link_state = LS_DOWN;
qdev->port_link_state = LS_DOWN;