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Registered: ‎11-03-2010

Lost IRQ on petalinux / microblaze / xps_intc

We have following setup:

 - An external chip connected to the FPGA.

 - Microblase + xps_intc.

 - external chip's interrupt line connected to the xps_intc.

 - the irq configured to rising edge.

 - petalinux v0.3 running on the microblaze. 

 - driver registered to this irq


The external chip is generating an interrupt every second (if its interrupt is cleared onchip).

The driver once done with the interrupt handling clears the interrupt on the chip.

Expected behavior is a call to the driver every second, however 

after couple of interrupts  (~1-20) the driver is not called any more even though the external chip generated an interrupt.


It has been verified with a counter that every time the driver is not called the counter - (corresponding counter in /proc/interrupts) is increased by 1.


The interrupt handler in the driver only schedules the bottom half (which is responsible for clearing the interrupt) then returns with IRQ_HANDLED. The bottom half runs within 1s although it does't matter when the interrupt is cleared onchip.


What could be the reason for the lost interrupt?



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