Messages in this thread Patch in this message | | | From | David Brownell <> | Subject | Re: [PATCH] Define a NO_GPIO macro to compare against and to use as an invalid GPIO | Date | Fri, 8 Feb 2008 15:43:42 -0800 |
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On Thursday 31 January 2008, Guennadi Liakhovetski wrote: > As discussed on i2c mailing list with David Brownell, and number > outside of the 0...MAX_INT range is invalid as a GPIO number. > Define a macro, similar to NO_IRQ, to be used as a deliberate > invalid GPIO, rather than defining a is_valid_gpio() macro.
Actually I thought that what you needed was an is_valid_gpio(); your motivation was that you needed a predicate.
The problem I have with a #define for a single such invalid GPIO number is that people will inevitably start to assume it's the only such number. In particular "if (gpio == NO_GPIO) ..." is by definition incorrect.
So I'd really rather see a predicate like is_valid_gpio().
If you want to designate one value for use as an initializer, then I'd rather see a simple
#define NO_GPIO (-EINVAL)
without any option for arch-specific overrides ... along with a comment that this is only *one* of the numerous values which will fail is_valid_gpio().
- Dave
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de> > > --- > > As gpiolib doesn't seem to have an own mailing list, sending it directly > to LKML. > > include/asm-generic/gpio.h | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h > index f29a502..806b86c 100644 > --- a/include/asm-generic/gpio.h > +++ b/include/asm-generic/gpio.h > @@ -16,6 +16,10 @@ > #define ARCH_NR_GPIOS 256 > #endif > > +#ifndef NO_GPIO > +#define NO_GPIO ((unsigned int)-1) > +#endif > + > struct seq_file; > > /** > -- > 1.5.3.4 >
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