AM3357: MDIO usage for both CPSW and PRU-ICSS

Gunter Schmer

Part Number: AM3357

Hi,

we are running into pinmux pressure and would need to remove the MDIO_PRUSS if at all possible.

A customer is using one RMII interface on the CPSW, and two MII interfaces on PRUSS.

In general can both the RMII connected PHY and the MII connected PHYs be controlled with one MDIO interface, aka the normal MDIO?

Is this still the case when using e.g. a PRU based EMAC_LLD, or would that require teh MDIO_PRUSS?

Is this still the case when e.g. running an Ethercat slave application with Ethercat slave firmware?

Thanks!

--Gunter

over 6 years ago

0 Garrett Ding over 6 years ago

TI__Mastermind 43296 points

Gunter,

When using PRU based EMAC_LLD as well EtherCAT slave firmware, it does require MDIO_PRUSS.

It might be possible to use one MDIO interface to manage both RMII interface from CPSW and MII on PRUSS. I will let hardware apps to confirm. But the customer has to update the ICSS EMAC LLD and EtherCAT application.

Regards,
Garrett

0 Gunter Schmer over 6 years ago in reply to Garrett Ding

TI__Genius 14212 points

Hi Garrett,

in the two cases with PRU based EMAC_LLD and Ethercat slave, can you confirm that the MDIO based configuration would only require an ARM side driver code change, and not a change to the PRU firmwares?

If it is an ARM side driver change, that would be manageable. It becomes more tricky if it is requiring a change to the PRU firmwares.

Thanks,

--Gunter

0 Gunter Schmer over 6 years ago in reply to Gunter Schmer

TI__Genius 14212 points

Hi Garrett,

wanted to add to the question, what would be required to ARM side driver and/or PRU firmware to share the MDIO interface when running PRU firmware for HSR, PRP, PTP.

Regards,
--Gunter

0 Garrett Ding over 6 years ago in reply to Gunter Schmer

TI__Mastermind 43296 points

Gunter,

PRU firmware doesn't configure/modify the PHY settings and all changes are required in ARM driver side. The application report may help understand the details of MDIO/PHY configuration and required changes - www.ti.com/.../spracc8.pdf

Regards,
Garrett

0 -DK- over 6 years ago in reply to Garrett Ding

TI__Mastermind 27890 points

Gunter,

I've checked this with the team internally and what you are suggesting isn't supported. Please continue to use dedicated MDIO for both PRU and CPSW.

0 Gunter Schmer over 6 years ago in reply to -DK-

TI__Genius 14212 points

Dave,

could you let me know where the issue is to support using the general MDIO for configuring PRU connected PHYs?

Thanks,

--Gunter

0 -DK- over 6 years ago in reply to Gunter Schmer

TI__Mastermind 27890 points

Hi Gunter,
It's simply not a currently supported configuration. No work has been done to evaluate, implement, or characterize it.

I did cluster this as a "feature request" so it is possible it could be looked into down the road.

Feel free to bubble this up internally if you feel the use-case is critical and deserves resourcing scrutiny.

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AM3357: MDIO usage for both CPSW and PRU-ICSS