J721S2XSOMXEVM: c7 dsp Streaming Engine

Hi,

Part of the behavior depends on the ISR and what behavior you would want after returning to the ISR. However in general, under the assumption that you are interested in using SE with the following behavior - 

1. Program has Function A which is running and utilizing SE0
2. Interrupt is triggered
3. ISR uses SE0 for another operation
4. Program returns to Function A 
5. Function A continues with SE0 at the exact state that SE0 was at step 2 when the interrupt was triggered

Then the general steps would be the following:

1. SE state is frozen by hardware when the ISR is entered (no explicit action needs to be taken by the program)
2. SESAVE instruction is used by the ISR itself to save current SE state to memory
3. Other ISR tasks and whatever streaming engine utilization by the ISR
4. At the end of the ISR, SERSTR instruction is used by ISR itself to write back the saved SE state
5. When leaving the ISR and jumping back to Function A, SE will then resume at whatever state was loaded back at step 4 automatically

Essentially, if the same streaming engine will be used by the ISR, steps 2 and 4 will need to be included by the ISR so that the SE state is properly preserved by state 5. 

Without those steps, the behavior SE would show would be determined by what the ISR actually does with streaming engine. I'd imagine you would see unexpected behavior such as reading from the wrong memory region. 

Best,

Asha