PS_DMA

Hello,

Iu2019m using PS_DMAC to transfer data. But the DMA Controller needs a lot of time to start the DMA transfer using u201CXDmaPs_Startu201D. Why did the DMA Controller need this long time even u201CXDmaPs_Startu201D was used for a different channel before? Is there a way to reduce this time for multiple DMA-transfers?

Thanks in advance

0 Former Member over 10 years ago

https://github.com/shakith/zedboard/blob/master/Documentation/DMA-API-HOWTO.txt
This might help...
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0 Former Member over 10 years ago in reply to Former Member

particularly, this:
"If you need to use the same streaming DMA region multiple times and touch
the data in between the DMA transfers, the buffer needs to be synced
properly in order for the cpu and device to see the most uptodate and
correct copy of the DMA buffer."
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0 Former Member over 10 years ago

Hello HarbingerZjC,

Thanks for your reply. Iu2019m programming without Linux. Iu2019m not sure if I understand it right. The DMA uses a buffer to safe the source memory content before transferring it to destination memory. Right? Is this buffer meant?

I measured 4,875u00B5s to safe 4Kbyte of data into PL over AXI. The DDR3-RAM is much faster, so I think that reading the Data from DDR3-RAM into the DMA_buffer have to be much faster than writing it from buffer into PL, but it takes 5 to 6 times as much.
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0 Former Member over 10 years ago

Is it possible to start two or more Channels in parallel, like it is described in ug585 TRM page 207.
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