Setup Hold times for Cyclone IV Flops

Hello Rysc, thanks for the reply.

Ref: (are you asynchronously sampling data, and just trying to get an idea of how often it will go metastable? that's the only thing i can think of where these might be important)

No, actually I am trying to Mux two data streams at 1x clock rate to a single stream at 2x clock rate. Both 1x and 2x clocks are phase (pos edge) aligned. Data is launched and latched by flops on respective domains.

I have an internally generated enable signal, which basically toggles on every pos edge of 2x clock. I use it to capture/mux the 1st and 2nd stream.

My concern is that the instance I am capturing the 2nd stream, at the same time (plus the Tco + Tpropagation delay from Source flop) the output of 2nd stream would be changing too. So my hold time at the latching flop would be Tco + T propagation delay – any positive clock skew on clk2x.

Higher this positive skew, lower available hold time.

Is this something which the tool can handle itself, or using a particular constraint would be recommended for a case like this?