lkml.org 
[lkml]   [2008]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] Define a NO_GPIO macro to compare against and to use as an invalid GPIO
Date
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
>




\
 
 \ /
  Last update: 2008-02-09 00:47    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site