According to STM32F407 reference manual page 313, memory to memory mode in DMA is a mode that doesn't need any triggering request from a peripheral and it will happen just after the stream enable bit is set. (also we know from the reference that only the DMA2 could handle memory to memory data transfer) :
So the question is for a transfer between two integer array defined in the memory area, which stream of DMA2 must be enabled and which channel of this stream must be used to have a DMA transfer without any peripheral triggering and only when enabling the DMA stream?
In fact what i want is sending some data from a buffer array in the memory area to a GPIO output data register. As is said what i expect to happens is when stream is enabled the transaction just happens but the result was not what i expected and no data is sent to that GPIO output data register. I want to use memory to memory DMA mode because it doesn't need any extra triggering