I see that the Zed board connects the Ethernet at 1.8V in bank 501. Is it possible to make this bank 3.3V and run the RGMII at this voltage? I've heard there may be an issue with Zynq-7000 running RGMII at 3.3V. It does appear that this may be the case since the Zed has the bank at 1.8V and has to use a voltage translator to get 3.3V at the SD interface instead of just changing the bank voltage to 3.3V.
