[PATCH v2 1/3] gpio: Use __gpiod_request directly

[Alexandre Courbot]

On Sun, Aug 30, 2015 at 4:44 PM, Markus Pargmann <mpa at pengutronix.de> wrote:
> There is no reason to find out chip and hwnum to use to request a gpio
> and get another gpio descriptor. We already have the descriptor we want
> to use so we can directly use it.
>
> Signed-off-by: Markus Pargmann <mpa at pengutronix.de>
> ---
>  drivers/gpio/gpiolib.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 79a0b41ce57b..872fdd3617c1 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2189,25 +2189,20 @@ EXPORT_SYMBOL_GPL(__gpiod_get_index_optional);
>  int gpiod_hog(struct gpio_desc *desc, const char *name,
>               unsigned long lflags, enum gpiod_flags dflags)
>  {
> -       struct gpio_chip *chip;
> -       struct gpio_desc *local_desc;
> -       int hwnum;
>         int status;
>
> -       chip = gpiod_to_chip(desc);
> -       hwnum = gpio_chip_hwgpio(desc);
> -
> -       local_desc = gpiochip_request_own_desc(chip, hwnum, name);
> -       if (IS_ERR(local_desc)) {
> +       status = __gpiod_request(desc, name);
> +       if (status) {
>                 pr_err("requesting hog GPIO %s (chip %s, offset %d) failed\n",
> -                      name, chip->label, hwnum);
> -               return PTR_ERR(local_desc);
> +                      name, gpiod_to_chip(desc)->label,
> +                      gpio_chip_hwgpio(desc));
> +               return status;
>         }
>
>         status = gpiod_configure_flags(desc, name, lflags, dflags);
>         if (status < 0) {
>                 pr_err("setup of hog GPIO %s (chip %s, offset %d) failed\n",
> -                      name, chip->label, hwnum);
> +                      name, gpiod_to_chip(desc)->label, gpio_chip_hwgpio(desc));
>                 gpiochip_free_own_desc(desc);

Mmm I should have reviewed this patch earlier, but what bothers me a
bit is that it breaks the symetry that we had by calling
request_own_desc() and free_own_desc() in the failing case (as well as
in gpiochip_free_hogs). And in the end you still need to call
gpiod_to_chip() so I am not sure what the benefit is.

Sure, the code is less verbose, but at the same time it has become
slightly harder to understand. Semantically speaking
"request_own_desc()" is exactly the action we want to convey.
__gpiod_request() is more ambiguous.

Note that this is not a reject, I just wanted to stress that "less
code" is not necessarily the same as "easier to read".