Perhaps a better approach would be for Panfrost to hand over the struct regulator objects it has already got to the OPP framework. I.e. open code dev_pm_opp_set_regulators(), but instead of calling regulator_get_optional() simply populate the regulators we already have?
The other benefit of that is it would provide a clear hand-over of responsibility between Panfrost handling it's own regulators and the OPP framework picking up the work. The disadvantage is that Panfrost would have to track whether the regulators have been handed over or not.