Hi, 実 奥山 ,
As you know that the resistor pack RP2,RP3,RP4 and RP4 are used to reduce the signal reflection, from signal integrity analysis, they should be put close to SDRAM.
We have documentation which focuses on signal integrity for high speed signals.
https://www.nxp.com/docs/en/user-guide/IMX8MNHDG.pdf
The section 1.3.1. General information lists the documentation which focuses on the high speed board design, I think they are helpful.
BR
XiangJun rong