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C6678 SRIO - 4x mode and OutPortID

one and zero
Mastermind 18136 points

Hi Champs,

it seems that in 4x mode OutPortID is ignored. E.g. sending a packet with OutPortID set to 1 (instead of 0 like it should be) transmit still works fine (I would have expected an error). However in 4x mode only Port 0 exists.

Is this expected behavior?

Thanks and kind regards,

one and zero

 

 

  • 0
    TI__Genius 9915 points

    Are you connecting it to another device. It can negotiate the 4x mode down to 1x mode, if the other device is in 1x mode.

     

    Thanks,

    Arun.

  • 0 in reply to ArunMani
    TI__Mastermind 18136 points

    Hi Arun,

    that was not really the question, but your answer raises an interesting point.

    Say I configure 4x mode using Port 1. In case I connect to a 4x peer packets are sent out via Port 0 (only POrt 0 is supported in 4x mode, although configuring for Port 1 also works). From your answer I see the scenario that via negotiation we fall back to a 1x configuration. In this case packets would go out via Port 1?

    Thanks for clarifying both scenarios.

    Kind regards,

    one and zero

  • 0 in reply to one and zero
    TI__Mastermind 23525 points

    You are right, in 4X mode, there is one port only (port 0). If outbound traffic is working when using port 1 in 4x mode, it will work with port 1 in single port mode negotiated to a 1x width too.  Was this using LSU traffic, or TXU messaging?  Just curious since they take different approaches, i.e. the LSU allows port assigning per transaction and the TXU is predefined based on TX queue.   I will discuss with the designers, but to me if in this mode, port # should just be ignored.

     

    Regards,

    Travis

     

  • 0 in reply to tscheck
    TI__Mastermind 23525 points

    Yes, the designer confirms that each functional block (LSU & TXU) has logic that converts illegal outbound port #'s to a legal ports depending on the configuration.  So in your case everything other than port 0, would be converted to port 0.  If you were in 2 ports, 2x mode, then outbound traffic trying to use port 1 would be converted to port0 and outbound traffic trying to use port 3 would be converted to port2.

     

    Regards,

    Travis