AM6442: EPHY test without power supply

Hello Vaibhav

Thank you for the query. 

here is my understanding of the loopback testing.

Please refer below diagram. X indicate that the EPHY is not available.

In the loopback diagram below the MAC will start the transmission, send the packets and try to receive the packets. 

I do not know if this is enabled in the software.

I need to reassign this to a Linux expert to guide. There may be some changes that may be required - like skipping the EPHY loop back configuration and i am not sure on a way to do this. 

Regards,

Sreenivasa

Thanks Sreenivasa, 

I don;t this it is possible, However you have confidance! Let me wait for TI linux expert response. 

Kallikuppa Sreenivasa said:

I need to reassign this to a Linux expert to guide. There may be some changes that may be required - like skipping the EPHY loop back configuration and i am not sure on a way to do this. 

Please provide me guidance, How this is possible in Linux?

-

Vaibhav 

Hi,

Looking at the TRM section the first item to note is that the Link Status can be affected depending on the loopback mode selected. Why I mention this is that the Linux CPSW will either not initialize or will do a teardown if a Link loss is detected. Which loopback mode would be selected? At the moment what I see here is that setting up a link and enabling loopback in the PHY (depending on which mode) has the potential to cause the MAC to close if the link status is lost.

Why is loopback being requested for this issue? Is this to isolate or prove an issue? In the past there have been bare-metal code written specifically for this purpose to setup the interface and perform the loopback testing.

Best Regards,

Schuyler