We have a board which has it's own 8253[PIT] and 8259 [PIC]. The 8253
is configued to raise an interrupt in every 20ms. Everything works
fine, However in long run the driver stopped to get the timer
interrupt. So I added some diagnostics code which dumps the internal
registers of 8253 and 8259 during the failure case. This log shows
that the 8253 is counting correctly. The IMR is not masking the timer
interrupt and the bit corresponds to the timer interrupt is set in the
IRR. The timer interrupt bit is not set in the ISR register. So
conclusion I made here is that, 8253 raised on timer interrupt and
corresponding bit in IRR is set and it's waiting for the CPU to sent
the INTA, however the CPU is not acknowledging, so driver
interruptServiceRoutine is not called-up.
Question I have here is,
What should be done to identify why the CPU didn't send INTA?
What should be done to identify why the InterruptServiceRoutine is not
called-up?
Thanks.