I can't find i.MX 8QuardMax / QuadPlus register manual on nxp website
Hello William Gou,
The Reference Manual for the i.MX8QuadMax and i.MX8QuadPlus are not yet publicly available so their access requires an NDA. I would need to you please open a support case to receive more information on how to sign and NDA and obtain this document.
My apologies for the inconvenience. Regards,