HPS2FPGA Bridge Throughput

[SrLam9]

Hi,

I am working on a project where there is a DDR4 RAM connected to the HPS2FPGA bridge and the host sends data to be saved in the RAM. I am trying to improve the throughput from the HPS to the DDR4, but the fastest I have achieved is ~16MB/s.

The software is written in C and the system is running embedded Linux. I am using the mmap() function to write the data to the DDR4 RAM. The program just writes large chunks of data to RAM. I am using an array of memory mapped locations in the example, but the rate is the same with only one map.

numOfBytes = 0x1000000; for(i = 0; i < 32; i++) { ret = BridgeMap(HPS2FPGA, i * numOfBytes, numOfBytes, &ddr4Map[i]); ddr4Reg[i] = (unsigned int *) (ddr4Map[i]); for(j = 0; j < numOfBytes/4; j++) { ddr4Reg[i][j] = i; } }int BridgeMap(int bridgeType, int address, int numOfBytes, void ** pMap) { if(fd_bridge == -1) { return -1; } int bridgeOffset, pageAlignedAddress;   if(bridgeType == LWBRIDGE) bridgeOffset = LWBRIDGE_START; else if(bridgeType == HPS2FPGA) bridgeOffset = HPS2FPGA_START;   pageAlignedAddress = (address / 0x1000) * 0x1000; // get page aligned address *pMap = mmap(NULL, numOfBytes, PROT_READ | PROT_WRITE, MAP_SHARED, fd_bridge, bridgeOffset + pageAlignedAddress); if(pMap == MAP_FAILED) { printf("error mapping: %s\n",strerror(errno)); return -1; }   return pageAlignedAddress; }

How can I improve the data rate going from the HPS to RAM? Is there a better way to communicate data from the HPS through the HPS2FPGA bridge? Should I be using the F2SDRAM bridge instead?

Thank you

[Fawaz_Al-Jubori]

Hello,

The fastest way of transferring data between HPS and FPGA would be the use of DMA. memcpy and mmap are slow.

You can refer to the datamover example:

https://rocketboards.org/foswiki/Projects/Datamover

where it shows you how to transfer data from HPS to FPGA and vice versa.

Please let me know if you need further assistance,

thanks

[SrLam9]

Hi,

Where can I find the example files? When I click the link for the zip file, the directory is empty aside from the README.

Also I looked over the example (maybe the source files can help clarify), but something is still not clear to me. In my application, I would be receiving data from a host PC that needs to be saved on to RAM. The data comes in via Ethernet, and it ends up in an array after it is read. How do I transfer that to RAM or how can I find where that is located since the sgDMA needs a source and destination address.

Thank you

[Fawaz_Al-Jubori]

Hello,

I will check with our admin regarding the missing files. Once I get a feedback I will let you know.

Thank you

[Fawaz_Al-Jubori]

Hello,

the design files has been removed since it was built with an old Linux version. I will try to migrate the design to a newer linux OS and send them to you.

Thank you

[Fawaz_Al-Jubori]

Hello,

The design files cannot be migrated due to kernel module dependencies.

I am still working on getting a workaround to overcome this issue,

Thank you

[SrLam9]

Thank you, Is it possible to send me the old files first? I want to take a look at the code itself. Especially the HPS code to see how I can implement something similar on my end. -Sid

[Fawaz_Al-Jubori]

Hello,

My apologize for the late reply. I was able to fine the design files (excluding the kernel zImage file). It took some time to fine the linux module source code.

I am still working on the alternative solution which might take extra time to verify.

[SrLam9]

Hi, I will review these source files and let you know if I have any questions. Thank you

[BC9]

Have you had a better solution?

If yes, can you share it?

Thanks a lot!

[FPOPP1]

Hello,

I am also trying to start the data mover. This could be very useful in teaching SOCFPGA.

Any chance to have it up and running in the actual tool landscape / linux version?

Best regards,