Dual Ethernet in i.MX8 QuadMax

[cbrake]

We are trying to get dual Ethernet working on a i.MX8 QuadMax systems. Looking at the DT files, it appears most of the boards put both phys on the same MDIO bus. Our design puts them on separate MDIO buses. We can get one or the other to work, but when both are enabled, we have trouble talking to the phy on the 2nd port.

[ 13.087338] fec 5b050000.ethernet end1: Unable to connect to phy

Questions:

1) has anyone implemented a design with dual ethernet using two MDIO buses?
2) What device tree changes are required to get this to work?

[cbrake]

Thanks for the help, we were missing the following line:

fsl,mii-exclusive;

It is working now.

[JosephAtNXP · Accepted solution]

Hi,

Thank you for your interest in NXP Semiconductor products,

Could you share the record of what you've tried?

I've seen that 8M Plus EVK implements a separate MDIO, let's stick to that dts. Which seems that differs to 8QM's in a own mdio child node. Have you tried modifying this in both u-boot and linux dts?

Also, have this in mind.

Regards