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The reason for this came from VGA driver.
As i wrote, i tried to use MUX in all know ways (IF, CASE, WHEN, WITH SELECT) combined with clock and without clock, and every time i get the same warning messages
Without using MUX, everything is work just fine
I just want to understand, what are the reason/s to the warning messages and how i can solve this
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Using rst as clock by itself does not explain the problem but you should not do that. What drives rst. I know it is input to the module.
The quickest test is to remove that edge.