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Observer
Observer
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Registered: ‎07-24-2018

Where can I find more information about the 'completed' bit from the axi dma?

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Where can I find more information about the 'completed' bit from the axi dma?

In this manual: LogiCORE IP AXI DMA v7.12PG021 June 14, 2019

I found this section:

verlindenjan_1-1600429210981.png

Where can I found this 'completed' bit? Is it referring to ioc?

verlindenjan_0-1600429155878.png

Or does it refer to: DMA_COMPLETE => https://github.com/Xilinx/linux-xlnx/blob/master/drivers/dma/xilinx/xilinx_dma.c#L1241

 

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Moderator
Moderator
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Registered: ‎03-25-2019

Hi @verlindenjan:

Short Answer:

It refers to the "Cmplt" bit of the STATUS field on each descriptor (MM2S_STATUS[Cmplt] or S2MM_STATUS[Cmplt]).
s2mm.pngs2mmm.png

Long Answer:

On Scatter Gather mode, each descriptor within your descriptor chain will be fetched, processed, then updated (check Descriptor Management section from PG021).

On the update step, the DMA updates the STATUS field for each descriptor. One of the bits that will be updated is the "cmplt" bit, to mark that this descriptor has been processed.

Best regards,
Abdallah
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1 Reply
Highlighted
Moderator
Moderator
221 Views
Registered: ‎03-25-2019

Hi @verlindenjan:

Short Answer:

It refers to the "Cmplt" bit of the STATUS field on each descriptor (MM2S_STATUS[Cmplt] or S2MM_STATUS[Cmplt]).
s2mm.pngs2mmm.png

Long Answer:

On Scatter Gather mode, each descriptor within your descriptor chain will be fetched, processed, then updated (check Descriptor Management section from PG021).

On the update step, the DMA updates the STATUS field for each descriptor. One of the bits that will be updated is the "cmplt" bit, to mark that this descriptor has been processed.

Best regards,
Abdallah
-------------------------------------------------------------------------------
Please don't forget to reply, kudo and accept as a solution

View solution in original post