17.5.12.1 Mode Register Write

MRW transactions can be specified for either any single rank, or any combination of several ranks, by programming MRCTRL0.mr_rank.

If any part of the SDRAM’s MR register is updated by software, it is also the responsibility of the software to update corresponding INIT*.*mr* so that it is aligned to the SDRAM’s MR register. For LPDDR2/3, INIT* registers are used to perform SDRAM initialization after DPDX.