Required register configuration when switching to RGMII-to-Copper mode using software:
- Write 0x0040 to register 1DFh // Set Operation Mode to RGMII to Copper
- Write 0x1140 to register 0h // Reset BMCR
- Write 0x01E1 to register 4h // Advertise 100Base-TX and 10Base-T ability
- Write 0x0300 to register 9h // Reset GEN_CFG1
- Write 0x5048 to register 10h // Reset PHY_CONTROL
- Write 0x4000 to register 1Fh // Software Reset