AM4376: How do I set up the CPSW in single MAC mode?

Lukas Holm

Part Number: AM4376
Other Parts Discussed in Thread: AM625

Tool/software:

Hi,

I have a custom board that is based off the AM437x GP EVM. How do I set up the CPSW in single MAC mode? What I would like to achieve is packet forwarding between the two external Ethernet ports without CPU intervention.

Best regards,
Lukas Holm

8 months ago

0 Prashant Shivhare 8 months ago

TI__Guru 73261 points

The query has been assigned to the expert. Please expect a response within a day or two.

Thanks!

0 Schuyler Patton 8 months ago in reply to Prashant Shivhare

TI__Mastermind 40420 points

Hi,

Which Linux SDK are you using on the device?

This looked to be a DTS setting but this has changed as I do not see the dual_emac flag in the DTS files. I will need to research further.

Best Regards,

Schuyler

0 Lukas Holm 8 months ago in reply to Schuyler Patton

Prodigy 40 points

Hi Schyler,

We are using the Linux 5.10.145 RT. I have looked thru all DTS and DTSI files that are included in our project and I can't see that we are setting the dual_emac flag anywhere.

Best regards,
Lukas

0 Schuyler Patton 8 months ago in reply to Lukas Holm

TI__Mastermind 40420 points

Hi Lukas,

The AM437

This link is the AM625 one of the recent devices, the CPSW is different in this class and uses command ip commands to setup a bridge in the CPSW. Please take a look this documentation from the AM625.

https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/10_01_10_04/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/CPSW3g.html#bridge-setup

The command will setup a bridge. What I need to confirm the bridge is actually putting the cpsw into the mode you require.

Best Regards,

Schuyler

0 Lukas Holm 8 months ago in reply to Schuyler Patton

Prodigy 40 points

Hi Schyler,

Thank you for the suggestion. Unfortunately I haven't been able to test it. Our Busybox doesn't include the devlink command and I haven't been able to find out how to include it. Perhaps it would be easier to patch the driver somehow to set the switch_mode parameter?

Best regards,
Lukas

0 Lukas Holm 8 months ago in reply to Lukas Holm

Prodigy 40 points

Hi Schyler,

I never managed to get the "devlink" and "bridge" commands to work in Busybox, but I managed to get the CPSW into switch mode by patching the driver. I changed the initial setting of "data->dual_emac" from "true" to "false" in cpsw_new.c. I also had to set "ti,dual-emac-pvid = <0>" for both ports in the DTS file. After doing that, the CPSW comes up in switch mode on boot and as soon as both Ethernet ports are UP, packets are forwarded between the ports.

Best regards,
Lukas

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AM4376: How do I set up the CPSW in single MAC mode?