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Tzipi_Kluska
Visitor
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Registered: ‎01-19-2021

SGMII without phy - external loopback on Xlinix Zynq UltraScale+ RFSoC board

Hi,

I have a costume board with Xilinx Zynq UltraScale+ RFSoC. I'm using 3 PS_GTR transceivers as sgmii. 2 of them are connected to external Marvell phy and the third connects directly (fixed link - without phy).

In the manufacturing stage i would like to make sure that the direct sgmii interface is assembled correctly - so I made an external loopback between tx and rx sgmii signals. Now, Is it possible to transmit something through this external loopback and compare with the received data? Is it possible to ping with yourself? (simple ping command not working: "ping -I eth2 <eth2-ip-address>")

perhaps there is a 'patch' under the 'macb' kernel driver that someone can guide me through?

Thank you all,
Tzipi Kluska

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nanz
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Registered: ‎08-25-2009

Hi @Tzipi_Kluska ,

for fixed-link, you will need this patch:

https://www.xilinx.com/support/answers/69769.html

We have not provided all different patches but basically what the patch does is to disable AN bit in the pcs_control register. 

When you do ping, you can see tx and rx increment. before doing external loopback, you can also try GTR loopback as per blog:

https://forums.xilinx.com/t5/Design-and-Debug-Techniques-Blog/Debugging-Tips-when-using-GEM-on-Zynq-MPSoC-devices/ba-p/1027406

 


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Tzipi_Kluska
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Registered: ‎01-19-2021

Hi Nanz,

 

Thanks for your replay!

I used AR#69769 and it helped us – the sgmii-fixed-link is working in front of another device

My questions is – how can I examine this sgmii interface, when no device is connected in the other side (= when my card is standalone, for test issues).

I have the possibility to make an external loopback between the tx and rx lines. 

In this case, I've tried to ping myself and got no reply, neither saw increments on the tx/rx interface counters.

There is a software patch to achieve this goal ?

 

Kind Regards,

Tzipi Kluska

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nanz
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Registered: ‎08-25-2009

Hi @Tzipi_Kluska ,

Do you have external loopback cable connected? There isn't any patch needed for testing external loopback. You should see TX and RX counter increments. 


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Tzipi_Kluska
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Registered: ‎01-19-2021

Yes, I have the external loopback connected.

Even if the cable is not connected well, I should see tx increments, no?

I don't see anything if I ping myself. I think that the kernel driver blocks the packets when its recognize itself as the source and destination address....

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nanz
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Registered: ‎08-25-2009

Hi @Tzipi_Kluska ,

I believe you should see the counter increments. 

Please can you try with PCS loopback or GTR loopback and see if that works? 


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