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response ordering at AXI4 slave

1) is response ordering logic need to be developed at Slave side?

2) Consider Single master-Single slave connection, master issue the outstanding read command to slave with following transaction

           1st transaction:   ARID =4, ARLEN=10

           2nd transaction: ARID=4  ARLEN=3

           3rd transaction: ARID=5  ARLEN=18

           4th transaction: ARID=4  ARLEN=3

    Could slave give response as follows for the above transaction sequence?, where 1st transaction issued first and 4th issued last:

             4th transaction response first generated, then

             1st transaction response generated then,

             3rd transaction response generated then 

             2nd transaction response generated last.

3) if response generated like said above interconnect will give response to master IP like this by doing the re-ordering the response:

           1st transaction response,

           3rd transaction response

           2nd transaction response

           4th transaction response.

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  • Rather than just answer your question directly, think about what giving the response to the fourth transaction first would tell the master.

    This fourth transaction uses ARID=4, so the master knows that this response is for an ID=4 transaction, but is that for the first, second or fourth transaction ?

    The master doesn't know !

    So as the protocol states, you can only re-order transactions with different IDs. See section A5.3.1 in the protocol.

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  • Rather than just answer your question directly, think about what giving the response to the fourth transaction first would tell the master.

    This fourth transaction uses ARID=4, so the master knows that this response is for an ID=4 transaction, but is that for the first, second or fourth transaction ?

    The master doesn't know !

    So as the protocol states, you can only re-order transactions with different IDs. See section A5.3.1 in the protocol.

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