Re: [PATCH] gpiolib: Add some warn print for easier to debug

[Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>]

On Tue, Jul 7, 2020 at 5:09 PM mnlife <mnlife@xxxxxxxxxxx> wrote:
>
>   when I get gpiod optional failed, I am confused for a long time.
> finally I find out that because of the string con_id is too long,
> prop_name is truncated.
>
> Signed-off-by: mnlife <mnlife@xxxxxxxxxxx>
> ---
>  drivers/gpio/gpiolib-of.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index ccc449df3792..11740f292420 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -467,15 +467,20 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
>         enum of_gpio_flags of_flags;
>         struct gpio_desc *desc;
>         unsigned int i;
> +       int size;
>
>         /* Try GPIO property "foo-gpios" and "foo-gpio" */
>         for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
>                 if (con_id)
> -                       snprintf(prop_name, sizeof(prop_name), "%s-%s", con_id,
> -                                gpio_suffixes[i]);
> +                       size = snprintf(prop_name, sizeof(prop_name), "%s-%s",
> +                                       con_id, gpio_suffixes[i]);
>                 else
> -                       snprintf(prop_name, sizeof(prop_name), "%s",
> -                                gpio_suffixes[i]);
> +                       size = snprintf(prop_name, sizeof(prop_name), "%s",
> +                                       gpio_suffixes[i]);
> +
> +               if (size >= sizeof(prop_name))
> +                       dev_warn(dev, "prop_name %s is truncated with size %d\n",
> +                                prop_name, size);
>
>                 desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
>                                                 &of_flags);
> --
> 2.17.1
>

To me this isn't a reason for a warning. If anything, this should
simply be documented (if it's not already).

Bart