linux-kernel - Re: [PATCH v2 01/13] gpiolib: add gpiod_multi_set_value

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Message-ID: <CAMuHMdX0Kp_Rj5iQODW3omEYimE+taf+cgbEiHqWo3=fG3Am0Q@mail.gmail.com>
Date: Fri, 7 Feb 2025 17:44:41 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: David Lechner <dlechner@...libre.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Andy Shevchenko <andy@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>, 
	Michael Hennerich <Michael.Hennerich@...log.com>, Jonathan Cameron <jic23@...nel.org>, 
	Ulf Hansson <ulf.hansson@...aro.org>, Peter Rosin <peda@...ntia.se>, Andrew Lunn <andrew@...n.ch>, 
	Heiner Kallweit <hkallweit1@...il.com>, Russell King <linux@...linux.org.uk>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Vinod Koul <vkoul@...nel.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, Nuno Sá <nuno.sa@...log.com>, 
	Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org, 
	linux-mmc@...r.kernel.org, netdev@...r.kernel.org, 
	linux-phy@...ts.infradead.org, linux-sound@...r.kernel.org
Subject: Re: [PATCH v2 01/13] gpiolib: add gpiod_multi_set_value_cansleep()

Hi David,

On Fri, 7 Feb 2025 at 17:29, David Lechner <dlechner@...libre.com> wrote:
> On 2/7/25 3:10 AM, Geert Uytterhoeven wrote:
> > On Thu, 6 Feb 2025 at 23:48, David Lechner <dlechner@...libre.com> wrote:
> >> Add a new gpiod_multi_set_value_cansleep() helper function with fewer
> >> parameters than gpiod_set_array_value_cansleep().
> >>
> >> Calling gpiod_set_array_value_cansleep() can get quite verbose. In many
> >> cases, the first arguments all come from the same struct gpio_descs, so
> >> having a separate function where we can just pass that cuts down on the
> >> boilerplate.
> >>
> >> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> >> Signed-off-by: David Lechner <dlechner@...libre.com>
> >
> > Thanks for your patch!
> >
> >> --- a/include/linux/gpio/consumer.h
> >> +++ b/include/linux/gpio/consumer.h
> >> @@ -655,4 +655,11 @@ static inline void gpiod_unexport(struct gpio_desc *desc)
> >>
> >>  #endif /* CONFIG_GPIOLIB && CONFIG_GPIO_SYSFS */
> >>
> >> +static inline int gpiod_multi_set_value_cansleep(struct gpio_descs *descs,
> >> +                                                unsigned long *value_bitmap)
> >> +{
> >> +       return gpiod_set_array_value_cansleep(descs->ndescs, descs->desc,
> >> +                                             descs->info, value_bitmap);
> >
> > I am wondering whether this needs a check for !IS_ERR_OR_NULL(descs),
> > to handle the !CONFIG_GPIOLIB and gpiod_get_array_optional() cases?
>
> I don't think it is strictly needed, but could be convenient for future use
> cases. If we add it, should it be:
>
>         if (IS_ERR_OR_NULL(descs))
>                 return PTR_ERR(descs);

return PTR_ERR_OR_ZERO(descs);

(the compiler should optimize away checks common to IS_ERR_OR_NULL()
 and PTR_ERR_OR_ZERO()).

> or:
>
>         if (!descs)
>                 return -EINVAL;
>
>         if (IS_ERR(descs))
>                 return PTR_ERR(descs);
>
> ?

The former.

> For comparison, gpiod_set_array_value_cansleep() will return -EINVAL if the
> first argument is NULL.

That function cannot take an argument returned by a *_optional() call,
if I'm not mistaken.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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