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C6678 - how to slow down SRIO tx but maintain full Rx speeds

Eddie3909
Guru 10385 points

The C6678 LSU is capable of sending 1 MB. Is there is a way to slow down the tx, without using the EDMA  interrupt pacing.

In the C6472, we used interrupt pacing to put spacers between the 4KB blocks in order to give our target DDR time to service other clients. We still needed to receive data over SRIO at the 3.125 Gbps rate.
Is there a way to slow down SRIO tx without changing the rx rate?
  • 0
    Guru 10385 points

    -------Answer from Travis (Mucho Thanks) ----------------------


    Yeah the new SRIO peripheral in C66x can do very large transfers.  It is a completely new design from the LSU perspective and the physical layer buffering/management and scheduling.  There is no concept of outbound credit issues anymore, the LSU will block until available, so that should help out.  However, there is no mechanism to slow the transmission of packets.  It will try to send as fast as possible.  If you send NWRITE_Rs, it can only have 16 outstanding packets at a time.  So, if there are more than 17 packets to send as part of a transfer, it needs to receive one of the responses before it send the 17th request packet.  Other than that mechanism, I think you will have to delay your submissions to the LSU to throttle.



  • 0 in reply to Eddie3909
    TI__Expert 7250 points
    Glad to see this was resolved.