Disable MPU Before changing region properties in ARM Cortex R4F

Hi, I am working with ARM Cortex R4F. I am using MPU to create 3 Memory Regions (Flash, SRAM and DRAM). I work in Supervisor, IRQ or  FIQ Mode. When changing the Flash memory region from Memory mode to Device mode or vice versa, do I have to disable MPU ?

My code works fine without disabling it and as far as I have tested, nothing breaks. But I want to be sure if this is an acceptable approach and if there are any harmful effects

Thanks in Advance,

Karthik