Subject: Re: demuxing irqs

From: Anton Vorontsov <[email-masked]>
Date: Wed, 17 Sep 2008 01:42:10 +0400

On Tue, Sep 16, 2008 at 02:32:45PM -0400, Jon Smirl wrote:
> On Tue, Sep 16, 2008 at 1:49 PM, Scott Wood <[email-masked]> 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
> >> <[email-masked]> 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.

Or we can do the right thing, without messing all other gpio
controllers, i.e. implementing MAX_IRQ hacks. Right?

I still don't see any problems with .to_irq callback, can you
point out any?

-- 
Anton Vorontsov
email: [email-masked]
irc://irc.freenode.net/bd2