Note: This calibration stage is skipped for
data rates at or below 2,133 Mb/s. At these data rates, the data eye is wide enough
that prior calibration stages provide adequate DQS centering.
The final stage
of DQS read centering that is completed before normal operation is repeating the steps
performed during MPR DQS read centering but with a more difficult/complex pattern. The
purpose of using a complex pattern is to stress the system for SI effects such as ISI
and noise while calculating the read DQS center position. This ensures that the read
center position can reliably capture data with margin in a true system.