On Sat, 2006-04-08 at 14:10 +1000, Neil Brown wrote:
>
> To explain what I think is happening, let me start with a very simple
> case. A number of PCI devices (this one included) have a number of
> events which can trigger an interrupt. The events which are current
> are presented as bits in a register, and are ORed together (and
> possibly masked by another register) to make the IRQ line.
> When 1's are written to any bits in this register, it acknowledges
> the event and clears the bit.
> A typical code fragment is
> events = read_register(INTERRUPTS);
> write_register(INTERRUPTS, events);
> ... handle each 1 bits in events ....
>
Isn't a more typical IRQ handler:
while (events = read_register(INTERRUPTS) != 0) {
...handle each bit in events and ACK it...
}
Lee
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