This training aligns Read MDQS in the center of
the Read MDQ window at the data buffer. In this training mode, the controller
pre-programs the data buffer MPR registers with the expected pattern and issues the
commands. The data buffer compares the read data with the expected data and feeds back
the result on the DQ bus. Calibration finds the left and right edges of the Read MDQ
valid window and centers Read MDQS in it.
Table 1. MRD Center Training Register
||Data Buffer MRD taps [4:0]