Is MDC mandatory for Ethernet?

[Oitsh.1]

I want to use a SIP with ST32MP153 and it uses PC13 to PMIC wakeup, PC1 is used for MDC so I'm left with only PI8 so can't use active tamper.

I sit possible to use Ethernet without MDC so I can use PC1 for active tamper with PI8?

[Olivier GALLIEN · Accepted solution]

Hi @Oitsh.1​ ,

Since you are using a SIP, I recommand you use in priority the SIP provider support channel.

Anyway, this is some few hints I get from expert that may be relevant for you :

MDIO/MDC in maily used to discuss and configure PHY. Using a switch you needn't to use MDIOs pins BUT, you have to use an I2C connection to discuss with. This discussion is split in two:

1- register access to configure switch

2- Mdio bus interface to establish PHY features of the switch (autoneg/ link state..)

In both cases you use 2 wires. There are not muxed as MDIO but they do quite the same.

Now concerning MACto MAC and linux, it's possible to do it.

In your devicetree you have to declare a fixed-link node in your gmac node.

See Documentation/devicetree/bindings/net/dsa/dsa.txt and Documentation/devicetree/bindings/net/ethernet-controller.yaml for more details.

You will not able to configure PHY/switch, or you will not be able to execute ethtool to change some settings.

Olivier

[Oitsh.1]

Got it. Thanks!