demuxing irqs

[Jon Smirl]

On Tue, Sep 16, 2008 at 1:49 PM, Scott Wood <scottwood at freescale.com> wrote:
> On Tue, Sep 16, 2008 at 10:24:35AM -0400, Jon Smirl wrote:
>> On Tue, Sep 16, 2008 at 10:14 AM, Anton Vorontsov
>> <avorontsov at ru.mvista.com> wrote:
>> > Assume that GPIO 8 does not translate to any IRQ, but IRQ 8 is still
>> > valid virq b/c it is mapped for another IRQ controller (particularly
>> > lots of kernel code assumes that IRQ 8 is 8259 PIC's CMOS interrupt,
>> > the PIC and IRQ8 is widely used on PowerPC).
>>
>> Set the base in the GPIO struct such that this won't happen.  You can
>> set the base greater than MAX_IRQ.
>
> And then you'll conflict with some other subsystem that decides to engage
> in the same shenanigans.

That comment was target at GPIO's that don't support interrupts. Give
those GPIO numbers greater than MAX_IRQ in case someone tries to use
them with the IRQ subsystem. Then they'll get errors.

> Just allocate a chunk of virq space like any other cascaded IRQ
> controller.

That is what I did.

>
> -Scott
>



-- 
Jon Smirl
jonsmirl at gmail.com