From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeroen Hofstee <jeroen@myspectrum.nl>
Date: Thu, 12 Jun 2014 23:03:14 +0200
Subject: [U-Boot] unsigned int for gpio
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	<CAPnjgZ34PobG40SOOoL9mROdj25R-ueysL-5x2H47O2oy+bY2g@mail.gmail.com>
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To: u-boot@lists.denx.de

Hello Simon,

On wo, 2014-06-11 at 17:12 -0600, Simon Glass wrote:
> Hi Jeroen,
> 
> On 11 June 2014 15:37, Jeroen Hofstee <jeroen@myspectrum.nl> wrote:
> > Hello Simon,
> >
> > in commit 95a260a9
> >
> >
> > dm: Enable gpio command to support driver model
> >
> > Now that named GPIO banks are supported, along with a way of obtaining
> > the status of a GPIO (input or output), we can provide an enhanced
> > GPIO command for driver model. Where the driver provides its own
> > operation for obtaining the GPIO state, this is used, otherwise a
> > generic version is sufficient.
> >
> > you made the following change:
> >
> > -       int gpio;
> > +       unsigned int gpio;
> >
> > This breaks the code after it though:
> >
> >         /* turn the gpio name into a gpio number */
> >         gpio = name_to_gpio(str_gpio);
> >         if (gpio < 0)
> >                 goto show_usage;
> >
> > And causes warnings with clang like:
> >
> > common/cmd_gpio.c:159:11: warning: comparison of unsigned expression < 0
> > is always false [-Wtautological-compare]
> >         if (gpio < 0)
> >             ~~~~ ^ ~
> >
> > Do you recall why it is made unsigned?
> 
> This is because gpio_lookup_name() needs an unsigned (-ve values have
> no meaning). I think that is what we want ultimately, but perhaps we
> need to go back to int in the meantime. The simplest fix would
> probably be to use a separate unsigned variable for the driver model
> code, and go back to an int for the current (old) code. The difference
> is that driver model returns a separate error code, whereas the old
> code combines the GPIO and error into a single value.

ok thanks. I will leave it alone then for now. Since the default lookup,
simple_strtoul, is unsigned as well, it won't solve a common problem
anyway.

Regards,
Jeroen