Hello, We found that level interrupts are handled in the following way in the Linux kernel: 1. mask irq, disable it 2. ack irq, clear it in interrupt controller. 3. move irq, handle it in handler for the source. 4. unmask irq, reenable it. This sequnce results in bogus interrupts in the system. The reason is that, after step 2 but before step 3, interrupt controller sees that the interrupt source is high, and will re-assert the interrupt. After the interrupt handler returns and finish step 4, the bogus interrupt causes the sequence to start again. We solve this issue by changing the interrupt controller to do nothing in step 2, ack irq, if it is a level. In step 4, unmask irq, we ack the interrupt controller then, and then re-enable the interrupt. Since interrupt is level, and source interrupt handler only clears interrupts once in the handler, nothing will be missed. I am not sure whether we are doing the right thing, and why the Linux kernel chooses to handle level interrupt in that sequence. Thanks, Julie. Thanks, -- View this message in context: http://www.nabble.com/level-interrupt-handling-in-the-Kernel-tp22481320p22481320.html Sent from the linux-newbie mailing list archive at Nabble.com. -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs
