[PATCH v2] gpio: Add Avionic Design N-bit GPIO expander support
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri Aug 10 19:15:55 EST 2012
On Fri, Aug 10, 2012 at 10:41:58AM +0200, Linus Walleij wrote:
> On Fri, Aug 10, 2012 at 10:35 AM, Thierry Reding
> <thierry.reding at avionic-design.de> wrote:
> >> Consult the following article on LWN:
> >> http://lwn.net/Articles/470820/
> >>
> >> Then grep your gitlog and you'll see we got rid of it from ARM.
> >
> > Then why is there still the following in arch/arm/include/asm/irq.h?
> >
> > /*
> > * Use this value to indicate lack of interrupt
> > * capability
> > */
> > #ifndef NO_IRQ
> > #define NO_IRQ ((unsigned int)(-1))
> > #endif
>
> That's a question for Russell but I think it's basically there for
> old platforms, on a "don't use it"-basis. (Maybe a comment could
> be good.)
Just don't use it. It's there for old stuff which still needs fixing.
New code should not use it, and should test for one of:
irq <= 0
irq == 0
And new code should set irq = 0 to indicate a lack of interrupt.
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