Intel i210 serdes backplane issue

[MJohn23]

Hi,

We have an intel i210 and have it connected to a Vitesse VSC7420 using Serdes Backplane 1000-Base-KX, we have modified the firmware for VSC7420 to bypass SFP and ANNEG and are able to transfer packet to / from both devices, however on the TX side from i210 to VSC7420 we have encountered packet fragmentation / loss of sync / lost packets and very slow transfer rate, the RX side seems fine though. It could be possible to adjust the Serdes parameters on the i210 side, possible that the peak to peak differential voltage is too high for VSC7420, the only mention of that in the i210 datasheet is with regards to internal PHY, fiber specific control REG, page 26, register 26, which seems to have some amplitude parameter, but we don't seem able to access that properly through lanconf, the registers always read back as zero even after writing to them, I am not even sure that when in backplane mode the internal PHY can adjust the Serdes parameters since the output is the Serdes block and not the PHY.

So my question is, how to adjust Serdes parameters on the i210 ?

Is there a flash byte that can be adjusted? I cannot find one in the datasheet.

Any help provided would be gratefully appreciated :-)

[CarlosAM_INTEL]

Hello Martin,

Thank you for contacting the Embedded Design Community.

We are working to give you an update as soon as possible.

Thanks in advance for your patience and understanding.

Best Regards,

Carlos A.

[CarlosAM_INTEL]

Hello Martin,

Thanks again for contacting the Embedded Design Community.

Could you please confirm if this condition happens with the Marvell 88E1111 or 88E1112 part instead of the Vitesse VSC7420 that are currently using?

Please keep in mind that you should use a SGMII image on the i210.

Thanks again for your collaboration to solve this inconvenience.

Best Regards,

Carlos A.

[Natalie_Z_Intel]

Here is another thread to watch that you might find interesting: /message/13355?et=watches.email.thread# 13355 https://embedded.communities.intel.com/message/13355?et=watches.email.thread# 13355. LynnZ.

[MJohn23]

Hi Carlos,

Thanks for your reply, sorry that is not our application, SGMII is for connection to an external PHY.

We are using 1000-Base-X, the VSC7420 is an 8 port switch, we are using Serdes backplane in MAC to MAC configuration.

I look forward to your reply,

Kind Regards,

Martin.

[MJohn23]

Thanks very much for the info LynnZ will keep an eye on the other thread as well

[MJohn23]

Hi LinnZ, Hi Carlos,

I have now found the cause of the lost synchronization / slow throughput / lost packets.

By adjusting the VSC7420 deserializer frequency offset compensation to a wider range I have managed to get the MAC to MAC link working very well now.

Seems that it was not related to the Serdes peak differential voltage after all and the Serdes parameters on the i210 side do not need to be adjusted.

However it would still be useful to know for future reference if Serdes parameters can be modified as its not really covered in the i210 datasheet.

Kind Regards,

Martin.

[CarlosAM_INTEL]

Hello Martin,

Thanks for your reply.

Could you let us know how you are connecting the VSC7420 to the i210? Are you using one of the SGMII interfaces? If you are using the Vitesse VSC7420 switch, you should probably be using the SERDES KX image. That is what is normally used to communicate with a switch.

Thanks again for your cooperation to solve this inconvenience.

Best Regards,

Carlos A.

[MJohn23]

Hi Carlos,

Thanks for your reply,

Yes you are correct, we are Serdes to Serdes, therefore MAC to MAC configuration and I confirm we are using the Serdes KX image.

We have this now at last working really well, although had to change quite a bit of code in the Vitesse firmware to get it working.

Kind Regards,

Martin.

[CarlosAM_INTEL]

Hello Martin,

We are glad to hear that the provided information was useful to you.

Please do not hesitate to contact us again if you will have more questions related to Intel Embedded devices.

Best Regards,

Carlos A.