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Issue with AIF2 descriptors in Keystone 2 architecture

Lee Chong
Prodigy 80 points

Hi ,

I am using C6638K2K DSP and have the issue I have faced is described as below.

When I try to use AIF2 Links 0,1,2 and push the descriptors in the AIF2 Tx queue, I get the descriptors back to the Free Descriptor Queue and can POP them back and reuse them and my application runs smoothly.

But when I use the Links 3,4,5 and try to push the descriptors, all the descriptors are getting exhausted.  

Please guide me how how to resolve this issue.

Thank you.

Lee

  • 0
    TI__Mastermind 21025 points
    This could be for several reasons. Most likely something isn't enabled and the descriptors are still sitting in the Tx queue(s). This can easily be checked by looking at the 32-bit word at this address: 0x02a40000 + (queue_number * 16). This is the number of descriptors currently in the queue "queue_number".
    One possibility is that the AIF2 Packet DMA channel (0..127) associated with the Tx queue (512..639) has not been enabled. Do your channel numbers change when you change to links 3-5?
  • 0 in reply to db_woodall
    Prodigy 80 points

    Hi db_woodall,

    Thanks for the response. 

    I use the the queue numbers 512 and 513 for all the links(0-5). Also when I try to read the memory location that you've specified, I see the exact number of descriptors(256, since my application needs 256 decriptors) that I have pushed into the Tx Queue.

    How ever I am yet to figure out how the DMA channel(0..127) is mapped to the Tx queue(512-639) if I am using Links 3,4,5.

    Request you to give me some insights on the same.

    Thanks and Regards,

    Lee

  • 0 in reply to Lee Chong
    TI__Mastermind 21025 points

    See section 5.1.1.1 of the AIF2 UG. Typically, AxC's map to packet DMA channels and to links.  There is a CPRI DMA LUT for this.  As stated in the UG, "It is illegal to map streams from different links to the same DMA channel".

  • 0 in reply to db_woodall
    Prodigy 80 points

    Hi db_woodall,

    Sorry to inform you this now, we are using OBSAI instead of CPRI.

    And the UG says that same DMA channels can be programmed to different Links in Section 5.1.1.2.

    Please correct me if my understanding is wrong.

    Regards,

    Lee

  • 0 in reply to Lee Chong
    TI__Mastermind 21025 points

    I think section 5.1.1.2 is saying that OBSAI has a different method of mapping than CPRI. Section 5.3.2 gives more details on it.  The fact that your descriptors are not leaving the Tx queue implies that AIF2 is expecting them elsewhere.

  • 0 in reply to db_woodall
    Prodigy 80 points
    Sorry for the late response.. The problem has been solved. I have tried reading the PE registers of AIF2 and found that we are writing into the wrong register to enable the PKTDMA Channel.
    Thanks for the Help.

    Cheers..!!
    Lee Chong
  • 0 in reply to Lee Chong
    TI__Guru* 81335 points
    Hi Lee Chong,

    Thank you for the update. We are glad to know that the issue has been solved.