This problem affects DDR2 and DDR3 products.
Certain device and board skew combinations may experience calibration failure. During calibration failure, the EMIF Debug Toolkit may report the following error:
Error: Read Calibration - No working DQSen phase found
This error may indicate that the calibration routine has failed to complete DQS enable calibration.
This issue may be more likely to occur with DDR3 interfaces operating at a frequency of 667 MHz or higher.