Re: ISA vs PCI interrupt handling

Alan Cox (alan@lxorguk.ukuu.org.uk)
03 Apr 2003 11:43:37 +0100


On Iau, 2003-04-03 at 00:20, Krzysztof Halasa wrote:
> Hi,
>
> A simple question: there are drivers for ISA and PCI devices. The IRQ
> handlers are registered with request_irq(flags = 0) or
> request_irq(SA_SHIRQ) for PCI.
>
> In both cases, the device raises an IRQ line and the handler is called.
> Does the handler have to make sure the device has lowered the IRQ?
> I mean, in situation where the handler terminates with the IRQ line
> being still active, will the handler be called again, or will the
> driver deadlock? Does is behave differently on ISA and PCI?

For PCI at least you must mask the IRQ on your device in that situation.
It must also be masked on the device not via disable_irq

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