Version Found: MIG UltraScale v6.1
Version Resolved: See (Xilinx Answer 58435)
Due to improper write calibration and read valid calibration results, MIG UltraScale QDRII+ designs may see calibration failures or intermittent data errors in hardware.
This issue only affects QDRII+ memory interfaces and failures are most commonly seen at cold temperatures and in the 500-550MHz range but can occur across all temperature and frequency ranges.
To resolve the issue please upgrade to Vivado 2015.1 and MIG v7.0 as improvements have been made to the MIG UltraScale QDRII+ calibration algorithm that address this issue.
05/01/2015 - Initial Release