Read Per-Bit deskew is performed on a per-bit basis whereas Read DQS centering
is performed on a per-nibble basis. During per-bit deskew, a predefined training pattern
of 101010... is read back from the DRAM while DQS
adjustments (PQTR and NQTR individual fine taps on DQS) and DQ adjustments (IDELAY) are
made. At the end of this stage, the DQ bits are internally deskewed to the left edge of
the incoming DQS.