Stratix IV GX - QDR w/ Uniphy

Getting through calibration was a false positive. The sequencer will eventually get the correct data for the valid calibration part of the state machine. The latency calibration usually fails right away further complicating things when it added margin causing the latency counter to roll over.

Now that I have added protection to that counter my bad results are more consistent. Usually only 1 sometimes 2 beats of the read are wrong. I do occasionally get the correct value, as calibration has shown. I'm not sure there is anything I can do on-die to correct this. I still don't know why it is occurring, but it seems to have something to do with the QDR itself. Any thoughts?