I have the DCM input constrained with a frequency that is in spec. However, the warning below is reported:
"WARNING:Timing:2798 - The output clock %s from DCM %s has a period (frequency) specification of %d ps (%.2f Mhz). This violates the minimum period (maximum frequency) of %d ps (%.2f Mhz)."
This warning is specific to the output of the DCM. The message states that the output of the DCM is not within specifications.
If you are using the DCM to increase the frequency of the clock, make sure that the output of the DCM does not exceed the specified maximum frequency.
Also, some DCMs have a Maximum RANGE and a Maximum SPEED mode that can change the allowed output frequencies of the DCM. Make sure that you are operating in the correct mode.