[U-Boot] unsigned int for gpio

[Simon Glass]

Hi Jeroen,

On 11 June 2014 15:37, Jeroen Hofstee <jeroen at 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.

Regards,
Simon