The allowed values for Write Recovery for DDR3 are 5, 6, 7, 8, 10, 12 and these values are calculated by rounding off the value of 15000/tCK to the next integer. In cases where 15000/tCK is evaluated between 8 and 9, the Write Recovery should be rounded off to 10. The controller however, is rounding off to 9 for conditions where 15000/tCK is greater than 8, but less than 9. This is resulting in tRP (Read/Write to precharge) violations at the Memory Side. These violations can be ignored.
The rounding issue is fixed in MIG v3.3, which is available with ISE Design Suite 11.4.