How to handle this hold time violated?

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Thanks so much, Kaz. That is clear and I will try this later. The only thing is now CK_Scan is two clk period latency, which you have mentioned.

How do you think the hold time violated? Why TimeQuest think the launch clock is "clk_300ns", and latch clock is "clk"? For my understand, both launch and latch clocks are "clk".

Thanks.

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Latency is one clock only, not two.

Hold violation occur commonly with gated clk or bad phase shift.

I don't know about your code but it could be timequest is referring to the clocks that are used for your counters i.e. those in the top enable statement.