Communicate with FPGA using PCIE on the IMX8MM platform

[charleshuang]

Hi NXP team,

Our customer try to alloc a DMA memory and using the DMA memory to communicate with FPGA using PCIE on the IMX8MM platform. 

The problem is the imx8mm ARM can write to FPGA through DMA memory, but FPGA cannot write data to dma memory.

Does imx8 allow external devices to access DMA memory? I also upload the source code as the attachment. Could you please help to give us some suggest? Thanks.

[kevinYang]

Hi Brian_lbarra,

   We used the driver and fpga, tested on x86 ubuntu18.04, the driver can read the dma memory data, and the communication was successful. But communication failed on the imx8mm.Thanks.

[brian14]

We can discard the incorrect FPGA operation, but the test I suggested is to rule out a problem specifically in iMX8MM PCIE.
Could you try PCIE communication between your iMX8MM and another iMX8 board?
This test is to discard both parts of communication, then we can check the issue when you interface the FPGA and iMX8MM.

Best regards,
Brian.

[kevinYang]

Hi Brian,

    FPGA uses bus master dma access, DMA in the FPGA end, and does not use imx8mm DMA. We can read and write the bar0 register of FPGA in imx8mm, we can also apply for a section of dma memory through imx8mm, write data into this section of memory and tell the address to FPGA, FPGA can access this section of memory and obtain data, but FPGA can not write data into this section of memory. Does our imx8mm support such a way? If so, what should we do? Thanks!

[brian14]

Hello!

To continue with the case:

What OS and version are you using on iMX8MM?
Do you configure the SCU or Device Tree?

This information helps us to evaluate the problem when FPGA writes to iMX8MM.

Best regards,
Brian.

[brian14]

In this case, we recommend using another iMX8MM EVK and testing the communication using PCIE to discard problems with iMX8MM, if this test pass without problems the problem could be in the FPGA.