Why does the CPU frequency still decrease after a successful OCC reset?

[Theo0208]

For P10, when an OCC detects an error requiring OCC Reset, HTMGT will reset the OCC.
Before the OCC reset, the CPU frequency was 4.00GHz, but after the OCC reset, the CPU frequency was 2.90GHz.
Why does the CPU frequency still decrease after a successful OCC reset?

[dcrowell77]

Once the OCC/PM reset is complete, the cpu should return back up to its previous operating frequency. If it doesn't that seems like a problem to me.

[cjcain]

Did the OCCs return to active state after the reset? If so, do you have the poll response?
If not, are their any PELs / Error logs? What system type and what was the power mode set to?