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Scholar ronnywebers
Scholar
994 Views
Registered: ‎10-10-2014

Use AXI SmartConnect instead of AXI Interconnect on wiki 'Linux DMA from user space'

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On the XIlinx wiki page 'Linux DMA from user space', I found a block diagram on how to connect the AXI DMA with the Zynq UltraScale+

I'm wondering why the S_AXI_LITE interface of the AXI DMA IP is connect through the 'old' AXI Interconnect IP, and not using the new 'AXI SmartConnect' IP. 

Q1 : Is there any specific reason to use the 'old' AXI InterConnect? Would it work equally well (or better?) with an 'AXI SmartConnect'?

Q2 : if 'yes', then would having an AXI SmartConnect require any adaption to the provided software example code on that wiki page? Or is this fully tranpsarant to the enitre software layer? 

 

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Xilinx Employee
Xilinx Employee
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Registered: ‎10-04-2016

Re: Use AXI SmartConnect instead of AXI Interconnect on wiki 'Linux DMA from user space'

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Hi @ronnywebers,

On the Wiki page, the block diagram uses AXI Interconnect between the M_AXI_HPM0_FPD port on the Zynq US+ PS and the S_AXI_LITE on AXI DMA because the connection wizard in Vivado at that time automatically instantiated AXI Interconnects for AXI-Lite interfaces. It was more of a passive design choice. The tools push the user that direction because there is ongoing work with SmartConnect to AXI4-Lite to make it as resource efficient as AXI Interconnect.

From a software perspective, the choice between AXI Interconnect and SmartConnect is transparent. The software shouldn't need to change. 

Regards,

Deanna

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Voyager
Voyager
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Registered: ‎02-01-2013

Re: Use AXI SmartConnect instead of AXI Interconnect on wiki 'Linux DMA from user space'

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https://forums.xilinx.com/t5/AXI-Infrastructure/Converting-from-AXI4-Interconnect-to-SmartConnect-causes-design/td-p/936725

I still use Interconnects everywhere. To put that in perspective, I got my first smart phone this past September.

-Joe G.

 

Scholar ronnywebers
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935 Views
Registered: ‎10-10-2014

Re: Use AXI SmartConnect instead of AXI Interconnect on wiki 'Linux DMA from user space'

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thanks @jg_bds for that link, I added a question to that thread to learn about the difference and different use cases of both interconnects, it's quiet confusing. Looks like the SmartConnect tries to be 'smarter' somehow than the 'old' AXI interconnect, but I'm not yet sure how / why. It looks a bit easier to connect (less clock pins etc). But I'm looking for some explanation on the diffs :-)

it may be very smart of you to wait so long to buy a smart-phone :-) Still not sure if we really needed this :-)

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Xilinx Employee
Xilinx Employee
865 Views
Registered: ‎10-04-2016

Re: Use AXI SmartConnect instead of AXI Interconnect on wiki 'Linux DMA from user space'

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Hi @ronnywebers,

On the Wiki page, the block diagram uses AXI Interconnect between the M_AXI_HPM0_FPD port on the Zynq US+ PS and the S_AXI_LITE on AXI DMA because the connection wizard in Vivado at that time automatically instantiated AXI Interconnects for AXI-Lite interfaces. It was more of a passive design choice. The tools push the user that direction because there is ongoing work with SmartConnect to AXI4-Lite to make it as resource efficient as AXI Interconnect.

From a software perspective, the choice between AXI Interconnect and SmartConnect is transparent. The software shouldn't need to change. 

Regards,

Deanna

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Don’t forget to reply, kudo, and accept as solution.
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