NAND Controller (ONFI compliant)

Be careful! Signal 'nand_rnb' must be (double)-re-clocked and not connected directly to the ONFI memory device, or metastability WILL occur.

I have doubts this is anyhow related here.

The 'clocking' had been verified for each signal multiple times.

As to connection of the signal to the device - please read the technical notes for the corresponding ONFI device and you will see that they all provide more or less detailed instructions on how the R/B pin of the device should be connected to. So, hardly related to the controller, if at all.