Hi! I'm using jesd204_phy v4.0. Vivado 2019.1. AXI4-Lite Management Interface is disabled. I tried to turn on Near-end PMA Loopback by changing port "gt_loopback" from 12'd0 to constant 12'b010010010010 inside jesd204_phy, but loopback wasn't working (I saw input RX signal instead had been sent TX) What can I do to turn on loopback?