Re: PCI interrupts

[Tommy Reynolds <reynolds@redhat.com>]

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It was a dark and stormy night.  Suddenly "Matthew Clark" <matt@eee.nott.ac.uk> wrote:

> In my development system the PCI card I am developing  the
> driver for reports (from the PCI config region) that it is using
> interrupt 5.  I can't register this interrupt as it is already
> in use by the USB controller.

PCI interrupts can be shared, but every handler must be registered with the
SA_SHIRQ flag on the request_irq() call.  Both the request_irq() and free_irq()
routines need a "dev_id" cookie to uniquely identify your instance of the
interrurpt handler.

You can see shared interrupts in "/proc/interrupts" because there will be a
comma-separated list of handler names for each IRQ level.

---------------------------------------------+-----------------------------
Tommy Reynolds                               | mailto: <reynolds@redhat.com>
Red Hat, Inc., Embedded Development Services | Phone:  +1.256.704.9286
307 Wynn Drive NW, Huntsville, AL 35805 USA  | FAX:    +1.256.837.3839
Senior Software Developer                    | Mobile: +1.919.641.2923

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