Read first: Read the mechanism and worked trace first
Illustrative timing conversion: a requirement is at least 15 ns and at least four controller ticks. At a 2 ns tick, the configured count must satisfy both requirements. These are hypothetical values, not a selected memory part’s timing.
Keep timing units with the programmed value — decision record
Apply the stated local assumptions; record actual platform values before using this as an implementation checklist.
Decision / observation | Required evidence | Consequence |
|---|---|---|
Convert 15 ns at 2 ns/tick | ceil(15/2)=8 ticks | Seven ticks would be only 14 ns |
Apply independent four-tick minimum | max(8,4)=8 | Do not choose the smaller requirement |
Clock changes to 1.5 ns/tick | ceil(15/1.5)=10 ticks | The old eight-tick setting is no longer sufficient |
A count can represent a shorter physical interval after the clock change. Recompute the cycle/time minima and apply the selected mode’s complete configuration sequence.
A common cold-boot sequence is reset DRAM → program mode registers → run the PHY's required training → verify results → enable normal controller traffic. The exact order, retry and fallback behaviour are platform contracts, not universal properties of every memory generation.
Where the platform's security and diagnostic policy permits, retain training results or summaries for field comparison. A trend can identify an operating-condition or margin change, but does not by itself identify whether the cause is silicon, package, board, power or configuration.
Cold boot vs warm boot may show different margins — test both.
Package change invalidates prior training assumptions.
Board vendor swap can change trace lengths and margins.