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

Alexandre Courbot
2015-09-23T04:25:28Z

On Sun, Aug 30, 2015 at 4:44 PM, Markus Pargmann <mpa@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@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".