Setting up second ethernet as RGMII Gigabit on Colibri i.MX7 eMMC 1GB

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I am assuming you have the second Ethernet PHY connected according to Table 5-5 RGMII signals.

  1. The Sabre reference design as well as many other designs share the one MDIO bus for both PHY’s but this is not true for the Colibri. If you connected the MDC/MDIO signals according to the table, they are connected to the FEC2 instance, hence the second PHY needs to be part of the fec2 device tree node. Also you are missing pin mux information for the MDC/MDIO pins.
  2. The clocking seems correct. I also would expect that the PHY appears even if clocks are not properly set up (since the MDIO bus allows to talk to the PHY indpendent of the main data signals)
  3. 0x73 enables pull-ups and uses a higher drive strength. Either way should work.
  4. I think not strictly. Afaik, the FEC driver defaults to scan the local bus for a PHY (FEC2->FEC2 MDIO bus), which would be what you want in your case. If you leave the mdio subnode away, then you also need to remove the reference in phy-handle. You still have to mux the MDC/MDIO pins according to you design…
  5. Ethernet controller can live without PHY. But in your case, the second Ethernet uses the PHY of the first Ethernet controller. Hence the mixup…