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66AK2G12: Relationship of packet DMA and Queue Manager

Michael Greenspan
Intellectual 575 points
Part Number: 66AK2G12
Other Parts Discussed in Thread: 66AK2H12

I need to program the NSS without using the drivers supplied by TI, and their seem to be a lot of missing and misleading things in the Technical Ref Manual.  In particular, I cannot find any information as to how to link a queue in the Queue Manager to a DMA channel, so that when I push a Packet Descriptor to that queue, it will be sent on a particular packet DMA channel.  Is there any documentation on this?  Is it hardwired, or programmable.  If hardwired, what are the connections.  If programmable, where are the registers to do this.

There is a lot of discussion about Navigator clouds, and different queue managers in the TRM, but there seem to be only one queue manager. and no real explanation of how to set up separate clouds, just a general discussion.

Final issue...the TRM has 64 different queues, the driver software 128, the training video speaks of 128.  Which is correct?  There are similar discrepancies in numbers of receive and transmit channels.

Perhaps you have some internal documentation that has more detail than the TRM?

Thanks for your help

  • 0
    TI__Intellectual 1515 points

    Hello,

    Thank you for the query.

    I will check internally and update you 

    Regards

    Rajashri

  • 0 in reply to Rajashri Hazarika
    Intellectual 575 points

    That thread provides the hardwiring information for the 66AK2H12,   This is different from the 66AK2G12, which has only 64 sets of QM registers.  Can you please provide the information for the 66AK2G12.?

  • 0 in reply to Rajashri Hazarika
    Intellectual 575 points

    Also, the link to the slide in that thread is not available...besides being for a different SoC.  

  • 0 in reply to Victor Kazmirenko
    Intellectual 575 points

    Thanks for your help.  Unfortunately, the slides and the referenced documents relate to a very different system.  The register set is completely different.  The names of the modules are completely different.

    The question remains whether any information is available for the 66AK2G NSS (Networking Sub System).  The only information I can find is in the 66AK2G technical reference manual, spruhy8i.pdf, and a bit in the product data sheet, but many, many details are missing.

  • 0 in reply to Michael Greenspan
    TI__Intellectual 1515 points

    Hello,

    I am checking internally with the team on the QM register and accordingly update you.

    Regarding this quote "many details are missing", can you please tell specifically.

    Regards

    Rajashri

  • 0 in reply to Rajashri Hazarika
    TI__Guru**** 188789 points

    Michael Greenspan

    The question remains whether any information is available for the 66AK2G NSS (Networking Sub System).  The only information I can find is in the 66AK2G technical reference manual, spruhy8i.pdf, and a bit in the product data sheet, but many, many details are missing.

    We checked internally and i am not able to find any additional documentation that i could share.

    We are checking internally and please expect some delay.

    Regards,

    Sreenivasa

  • 0
    Intellectual 575 points

    From section 11.13.2.4.3 Transmit Operation (Host Packet Type) in the 66AK2G Technical Reference Manual (TRM):

    "The Host writes the pointer to the Packet Descriptor into a specific memory mapped location inside the
    Queue Manager which corresponds to one of the Transmit Queues for the desired DMA channel.
    Channels may provide more than one Tx Queue and may provide a particular prioritization policy
    between the queues. This behavior is application specific and is controlled by the DMA
    controller/scheduler implementation."

    The words "a specific memory mapped location inside the QueueManager"  is not so helpful if there is no information as to what that specific location is.

    I am guessing it is Queue Register D for one of Queue Manager channels 4-12, based on kind of reverse engineering of the TI software.  But if you are selling this thing to customers, it would seem to be a simple matter of proper corporate ethics to provide the full information necessary to work with it.  You say "We checked internally and i am not able to find any additional documentation that i could share".  So I understand there is some additional documentation that you can't share. Can it somehow be made available?

    Supposing I was learning to drive a car, and I received instructions that when a traffic light changes to a certain specific color, I can go.  That is not very helpful.  I need to know what that specific color is (green?) before I can drive.  Same thing with the 66AK2G.  

    Another curiosity...the QM_REVISION_REG in the TRM is supposed to be 8EFC1900.  But when I read it with the debugger, it is 4E5D0106.  Is the 66AK2G12 now equipped with a different version of the QM?

    Also, the TRM shows registers QM_QUEUE_REG_A, B, C, and D as having 64 instances, but the driver software from TI uses 128 instances.  Which is correct?  If either?  There are several other instances of discrepancies of this sort between the driver software and the TRM, such as number os receive and transmit channels.

  • 0 in reply to Michael Greenspan
    TI__Guru**** 188789 points

    Hello Michael Greenspan

    Thank you for the additional inputs.

    Also, the TRM shows registers QM_QUEUE_REG_A, B, C, and D as having 64 instances, but the driver software from TI uses 128 instances.  Which is correct?  If either?  There are several other instances of discrepancies of this sort between the driver software and the TRM, such as number os receive and transmit channels.

    I am internally checking if there is any additional information available that i could share.

    With the  discrepancies you are seeing between the TRM and the driver, i would suggest you to reference the information available in the working driver to continue the development efforts  to program the NSS without using the drivers supplied by TI . 

    Regards,

    Sreenivasa