Hello
I met an issue of FIQ interrupt1023 occurred when two periodic interrupts existed: vector270: priority: 12, group1 (IRQ) and vector27: priority 16, group0 (FIQ).
When the fiq_exception got the INTID1023, I saw that ICC_HPPIR0: 0x1B (27), ICC_AP1R0: 0x1000 (active priority: 12). As the irq_exception will not mask FIQ, I suppose that when the CPU is handling vector270 (IRQ), vector27 (FIQ) comes and interrupts it. But as the priority of vector27 is lower than vector270, interrupt1023 is reported due to no sufficient priority. Is my understanding right ?
If so, what are the recommendations for irq and fiq handling when the system have both IRQ and FIQ interrupts enabled ?
BR, Grace
1023 means you didn't ack an interrupt. Under "normal" operation it's possible to get this, so IRQ/FIQ handlers should be written to cope with it. Typically what I'd expect is that the hander would just return (after clearing up any corrupted registers/stacks/etc). You didn't ack an interrupt, therefore the is nothing for the handler to do.
If you were repeatedly taking an interrupt, then getting 1023 back from the IARs, that would be unusual and worth investigating. So you might do some sort of logging to check if it's happening a lot.