Re: [PATCH v4 02/13] gpiolib: have a single place of calling set_config()

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Bartosz,

On Tue, Dec 24, 2019 at 1:08 PM Bartosz Golaszewski <brgl@xxxxxxxx> wrote:
> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>
> Instead of calling the gpiochip's set_config() callback directly and
> checking its existence every time - just add a new routine that performs
> this check internally. Call it in gpio_set_config() and
> gpiod_set_transitory(). Also call it in gpiod_set_debounce() and drop
> the check for chip->set() as it's irrelevant to this config option.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -3042,6 +3042,15 @@ EXPORT_SYMBOL_GPL(gpiochip_free_own_desc);
>   * rely on gpio_request() having been called beforehand.
>   */
>
> +static int gpio_do_set_config(struct gpio_chip *gc, unsigned int offset,
> +                             enum pin_config_param mode)
> +{
> +       if (!gc->set_config)
> +               return -ENOTSUPP;
> +
> +       return gc->set_config(gc, offset, mode);
> +}
> +
>  static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
>                            enum pin_config_param mode)
>  {
> @@ -3060,7 +3069,7 @@ static int gpio_set_config(struct gpio_chip *gc, unsigned int offset,
>         }
>
>         config = PIN_CONF_PACKED(mode, arg);
> -       return gc->set_config ? gc->set_config(gc, offset, config) : -ENOTSUPP;
> +       return gpio_do_set_config(gc, offset, mode);

These two lines are not equivalent: the new code no longer uses the
packed value of mode and arg!
Hence this leads to subsequent cleanups in commits e5e42ad224a040f9
("gpiolib: remove set but not used variable 'config'") and d18fddff061d2796
("gpiolib: Remove duplicated function gpio_do_set_config()").

However, what was the purpose of the PIN_CONF_PACKED() translation?
Why is it no longer needed?

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds