Unexpected speed drop in pcie transfer speed and possible illegal access causes smmu errors

I previously posted on “Jetson Orin Developer Kit - unexpected drop in PCIe transfer speed”.

I checked my library. I checked the results. The values that I wrote to Orin’s RAM from my FPGA is correct values. It successfully did write them. I don’t think this problem is caused by library. Also, this library works well on different platforms that has Intel or other Arm processor. I couldn’t solve problem. What else can I do? At least, can I try to disable smmu? Because I read other posts that smmu causes some problems on PCIe transfers.