MCU-PLUS-SDK-AM243X: How to use tsn stack on ICSSG DUALMAC port On am243x platform?

Hello Wang Bin,
Thanks for posting this question!

wang bin said:

Is it possible  the  tsn stack works  in  dualmac mode? 

A clarification - Do you intend to use ICSSG in dualmac mode with single ICSSG instance (that is, one mac port) or two ICSSG instances (that is, two MAC ports in MAC mode) ?

With regards,

Pradeep

Hi  PRADEEP HN，

       We use two ICSSG instances in MAC mode，and has 4 enet ports  total in our design. 

Let me check this internally and come back to you by Monday.

Thanks and regards,

Pradeep

Hi  PRADEEP HN，

    Do you have an answer to this question？

HI Wang,
 Yes, I did check this internally about the feasibility of this.
Since all the TI EVMs has only one ICSSG instance that is exposed out to PHY, we dont have out of box demo for your usecase with 4 ports. However, we will try to evaluate now on what changes we can propose  you to do support your requirement.
Can you please help me to clarify the below question,-
1. Do you like to use both the ICSSG instances in Dual MAC mode. That means, no packet forwarding between 4 ports at all?
2. Do you have a dynamic usecase where you want to switch between number of Ports? or it is always 4 MAC ports?

Thanks and regards,

Pradeep

Hi  PRADEEP HN，

     1. yes，our usecase use software for packet processing between 4 ports.

     2. we have a powerful switch outside ，so our design is  act as a terminal node.

HI Wang,
In the last released version, we dont have support to use two instances of ICSSG with gPTP stack. Do you prefer to wait for the next release (planned for March'24) or do you want me to suggest the changes to you, so that you can try on your own?

With regards,

Pradeep

Hi  PRADEEP HN，

      Next release is a long time to wait. I need you suggest the changes to me . Thank you.

Hi Wang,
 We are looking into it and would need some more time to come up with the proposal.
Thanks for your patience.

With regards,

Pradeep

Hi Wang,
  We looked into this usecase. As you may know in order to support 4 ports as gPTP relay instance, we need to use two ICSSG peripherals (ICSSG0 and ICSSG1). Each ICSSG peripheral has its own IEP clock that is used internally in ICSSG to timestamp PTP Rx and Tx events. In order to have a common time synchronized across all the four ports, we need to make sure both the IEP are synchronized. This implementation is not present in the gPTP stack.
However, time synchronization across two ports of single ICSSG in MAC mode is possible and we can provide the update to realize this.

Can you please share more details on the usecase : (1) Do you want to have four ports synchronized to a same time base? (2) In your topology, do you intend to have a common gPTP timeTransmitter (master) outside and AM243x ICSSG four ports as gPTP relay ? Are you controlling both the ICSSG peripherals from single R5F core ? 

With regards,

Pradeep

Hi  PRADEEP HN，

    in our application， the switch has  several ports and connect to icssg port  directly (two ports in icssg instance 1) . Another two ports is not directly connect to switch,  so I think one icssg port is a endpoint . Act as TSN EP Only role as shown blow. 

  So  for first question ,we not need  four ports synchronized to a same time base now，but maybe need in future. for second question , we want icssg port act role as TSN EP ONLY. for third question, yes, we have achieve running four ports on one R5F CORE with one network stack.

Hi Wang,
     Regarding:
1. 

wang bin said:

for first question ,we not need  four ports synchronized to a same time base now，but maybe need in future. for second question , we want icssg port act role as TSN EP ONLY.

wang bin said:

Another two ports is not directly connect to switch,  so I think one icssg port is a endpoint

1. Does it mean, you need gPTP time sync only on one of the PORT of ICSSG_instance_1 (in dual MAC mode), with gPTP endpoint? 
2. gPTP replay between ICSSG_instance_1_Port1 and  ICSSG_instance_1_Port2 is not needed. Am I right?

If this is the case, we will provide an example that will work for you in 9.2 release.

With regards,

Pradeep

Hi  PRADEEP ，

  I'm glad to hear this news. My answer to your question is as follows:

   1.yes ,it's look like this.

   2. What does gPTP replay mean？we use two ports （port 1 and port2 ）as two independent data channels.

Thank you.

Hi Wang,
 About -

wang bin said:

 2. What does gPTP replay mean？we use two ports （port 1 and port2 ）as two independent data channels.

Another term used for gPTP relay is 'Transparent Clock' as per 1588 spec. Similarly gPTP endpoint are called as 'Ordinary Clock' .
Please find the details and difference between PTP End points and Relay in the below diagram.

Please note that, for data path there is NO restriction. It is only that the PTP packets are 'relayed' from one port to another port. Hence, time sync between ICSSG1 and PC2 is NOT possible in gPTP endpoint.

As you per my understanding about your requirement, you DO NOT need "gPTP in relay mode". Please correct me if my understanding is wrong.

Thanks and regards,
Pradeep

Hi  PRADEEP ，

      In our application, We need to synchronize the time between one port and one switch （PC1 or PC2）separately ,  in order to support the 802.1qbv feature in future. Therefore, Maybe gPTP in Two Port Relay Mode is what we need.Is it right?

Hi Wang,
   Synchronizing only PORT1_ICSSG_Instance0 in end point will synchronize IEP of ICSSG0. This means, even with single PORT End point mode, both the ports of ICSSG_Instance0 shall be able to support 802.1qbv feature. Because, both ports use same IEP timing to 802.1qbv transmission. As you know there is only one IEP per ICSSG Instance.

The same is explained in the below diagram-

Please let me know if the above answers clarifies your query.

Thanks and regards,

Pradeep

Since there is no activity for more than 6 months, will close the ticket. Please submit a new ticket if there is still issues.

Br, Tommy