The RGMII port which connects the Ethernet PHY to AM335x has critical timing requirements that depend on specific PCB circuit trace delays. Some PHYs have registers that must be setup via the MDIO port to configure it to work with specific specific circuit trace delays of the PCB. Even if you find a driver for a specific PHY, you should not assume it is doing to work if the PHY has registers that need to be configured to match the PCB design. You may need to configure the PHY registers to match your PCB design if your PCB design doesn't have exactly the same delays as the PCB that was used to develop the driver.
You should have your hardware designer validate his design by performing a timing analysis of the AM335x connected to the PHY which you select. Once the custom design is ready for software, you may need to work with the hardware designer to know what delays need to be configured in the PHY.
Regards,
Paul
