I am trying to figure out how to transmit a single byte of data to my PHY on a custom T2080 board. I can communicate with the PHY via MDIO and read it's identifier and set it's LEDs. Now I want to set the PHY to loop back mode (I know how to do this) so that when I transmit data via the RGMII TX interface it will just loop back into the RGMII RX interface. However, I can't seem to find any info on where to write my data to so that I can transmit via the RGMII interface. This is bare metal by the way so I can't use any Linux API's to do the heavy lifting, but I am not trying to implement a full TCP/IP stack either.
Thank you for your help!