You can change the priority of every interrupt at any time.

But you should carefully evaluate, what can happen on any combination of interrupts in progress or not.


E.g. if you are already inside a low level interrupt and change its priority to high level, then it is possible, that the interrupt can interrupt itself a second time.

The priority bit would only be examined every time, if an interrupt was entered.
So changing the priority has no effect on all the interrupts currently in progress.


Peter