SSGDMA Bursting Manager Interface BAR

[jc_ddc]

Hello,

I am working on a PCIe interface for an Altera Agilex 5 device. The PCIe interface will have two BARs defined for accessing user memory and registers without DMA (ex. memory mapped to BAR 1, configuration registers mapped to BAR 2).

I intended to use the Bursting Manager (BAM) function of the Modular Scatter Gather DMA IP (MSGDMA) for the Agilex 5 since it allows multiple BARs to be mapped to the BAM. However, the MSDMA resource utilization exceeds that of the FPGA used for this design (it uses way more M20Ks than available).

That brings me to the Scalable Scatter Gather DMA IP (SSGDMA) for the Agilex 5. The resource utilization of this IP fits within the constraints of the FPGA. However, it seems that the BAM for this IP can only be mapped to BAR 1... is this correct? Is there any way to map multiple BARs (like BAR 1 and 2) to the BAM of the SSGDMA?

Thank you.

[jc_ddc]

Correction: Instead of "Modular Scatter Gather DMA IP (MSGDMA)", I meant "GTS AXI Multichannel DMA IP for PCI Express".

[Wincent_Altera]

Hi @jc_ddc ,

Yes, the BAM is mapped to BAR1 accordingly to the user guide

However, the MCDMA resource utilization exceeds that of the FPGA used for this design (it uses way more M20Ks than available).
>> Which OPN that you are using, if you are using the devkit according to the design example, by right you wont observed this problem.
>> IF you need to use your custom OPN , you may try to optimize the design memory utilization
>> https://www.intel.com/content/www/us/en/docs/programmable/683174/25-1/memory-optimization-m20k-mlab.htmlhttps://www.intel.com/content/www/us/en/docs/programmable/683174/23-3/memory-optimization-m20k-mlab.html

Regards,
Wincent

[jc_ddc]

Hi Wincent,

Thanks for your reply! I'm basing resource utilization off what's described on the resource utilization page of the MCMDA datasheet: https://www.intel.com/content/www/us/en/docs/programmable/847470/25-1-1/resource-utilization.html. 

The FPGA being used is the A5E013A, which only has 358 M20Ks available and a PCIe 4 x4 interface. Based off the resource utilization for the MCDMA, it seems we'd be unable to use with this part. 

Do you have any suggestions on how resource utilization for the MCDMA IP may be decreased?

Thank you!

[Wincent_Altera · Accepted solution]

Hi @jc_ddc ,

I check internally, unfortunately we do not have any well proven 100% design to reduce the resource utilization for MCDMA.
For effective working mcdma , I would strongly suggest to consider Agilex5 Modular devkit or Premium devkit.

Else you can try to start by minimizing the number of channels and FIFO depths in the MCDMA configurator. If that's insufficient, consider a simpler DMA IP or a custom solution if your resource constraints are very tight.

Regards,

Wincent_Altera