The SPI-4.2 User Guide states that the Sink core must be receiving a valid training pattern when the PhaseAlignRequest is asserted. However, the Sink core must be receiving a valid training pattern at the time Reset_n is deasserted.
If the valid training pattern is not available when reset_n has been released, the Sink core can get stuck in an unknown state and will issue DIP4 errors.
To work around this issue, do not deassert Reset_n until a valid training pattern is available on RDAT. The required startup sequence has been updated to reflect the new requirement. See (Xilinx Answer 16176).