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FabianL's avatar
FabianL
Icon for Occasional Contributor rankOccasional Contributor
2 months ago
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Avalon Transaction Responses & Bridges

Hello I have a question about the behavior of Avalon-MM Pipeline Bridges concerning the response signals. I have the following setup: 2 (or more) Avalon-MM Masters Master cmd_ctrl (supports Aval...
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  • ShengN_altera's avatar
    ShengN_altera
    2 months ago

    That was the reason, why we tried the response interface. I also expected the response codes to be propagated back to the master. But when I understand you correct, the Avalon response only works on a single interconnect and is not useable across bridges ist that correct?

    Yes, your understanding is correct.

     

    Can you don't use the bridge? Master get the response from slave?

FabianL's avatar
FabianL
Icon for Occasional Contributor rankOccasional Contributor
2 months ago

Hi Sheng, thanks for the update,

 

We tried the variant by holding waitrequest until a write command is fully processed already. However that does not work in case of pipeline bridges in between either, since e.g. for single word writes, the bridge accepts the write right away before the slave is triggered, due to its pipeline stage. Hence the initiating Master has also no control, when the write is actually processed at the slave side. ==> so that is not working either.

That was the reason, why we tried the response interface. I also expected the response codes to be propagated back to the master. But when I understand you correct, the Avalon response only works on a single interconnect and is not useable across bridges ist that correct? 

best regards

Fabian

 

  • ShengN_altera's avatar
    ShengN_altera
    Icon for Super Contributor rankSuper Contributor
    2 months ago

    That was the reason, why we tried the response interface. I also expected the response codes to be propagated back to the master. But when I understand you correct, the Avalon response only works on a single interconnect and is not useable across bridges ist that correct?

    Yes, your understanding is correct.

     

    Can you don't use the bridge? Master get the response from slave?

    • FabianL's avatar
      FabianL
      Icon for Occasional Contributor rankOccasional Contributor
      2 months ago

      In parts of the design this is an option. But the relevant parts are in a QSYS subsystem, which requires a bridge to have a single Avalon Slave port at the interface. Otherwise all Avalon-MM Slave Ports of the subsystem are exported individually, causing a real mess in the interface (we are talking about 5-10+ slave ports).

       

      So I guess we have to implement a independent handshaking mechanism on top of Avalon.

      Thanks for your explanations.