pll_locked can be used even when PLL sharing is set to No sharing.
(Reference) External Memory Interface Handbook
https://docs.altera.com/r/aigN1Vypic5yu3QMv5nT6w/e_kOvFPUCYoQauaWkPgaxQ
(Search for pll_locked)
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Category: External Memory Interface
Tool: Quartus® Prime
Device: Arria® V