I looked at the signal to the DDR device, the controller firstly issues commends to mode registers EMR2, EMR3, EMR and MR, then Precharge, refresh, load mode registers again. After this, it repeats the above steps for 3 times.
However, in the DDR2 device datasheet, it only requires 1 time of the above steps to initialize the device. Will those extra 3 times impact the operation? Is there anyone know why it repeats 4 times in total for the Initialization? Thanks!