linux-kernel - Re: [PATCH] leds: aw200xx: don't use return with gpiod_set

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Message-ID: <CAMRc=Met68e5c16ShiJ1mHQM-GSvautN_whVMGh53g3mx7OQSg@mail.gmail.com>
Date: Wed, 12 Feb 2025 17:39:16 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Lee Jones <lee@...nel.org>
Cc: Pavel Machek <pavel@...nel.org>, linux-leds@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] leds: aw200xx: don't use return with gpiod_set_value() variants

On Wed, Feb 12, 2025 at 4:55 PM Lee Jones <lee@...nel.org> wrote:
>
> On Wed, 12 Feb 2025, Bartosz Golaszewski wrote:
>
> > On Wed, Feb 12, 2025 at 9:59 AM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> > >
> > > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > >
> > > While it now returns void, it will soon be converted to return an
> > > integer instead. Don't do `return gpiod_set...`.
> > >
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202502121512.CmoMg9Q7-lkp@intel.com/
> > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > > ---
> > >  drivers/leds/leds-aw200xx.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/leds/leds-aw200xx.c b/drivers/leds/leds-aw200xx.c
> > > index 08cca128458c..fe223d363a5d 100644
> > > --- a/drivers/leds/leds-aw200xx.c
> > > +++ b/drivers/leds/leds-aw200xx.c
> > > @@ -379,7 +379,7 @@ static void aw200xx_enable(const struct aw200xx *const chip)
> > >
> > >  static void aw200xx_disable(const struct aw200xx *const chip)
> > >  {
> > > -       return gpiod_set_value_cansleep(chip->hwen, 0);
> > > +       gpiod_set_value_cansleep(chip->hwen, 0);
> > >  }
> > >
> > >  static int aw200xx_probe_get_display_rows(struct device *dev,
> > > --
> > > 2.45.2
> > >
> >
> > Lee, Pavel:
> >
> > If this is OK for you, can you please provide me with an immutable
> > branch so that I can pull it into the GPIO tree? It seems it's the
> > only such use-case in the tree apart from the gpio.h header that I can
> > fix locally. Alternatively you can just Ack this and let me take it
> > through the GPIO tree.
>
> I'm okay with it, but why do you need it?
>

For historical reasons gpiod_set_value() and its variants don't have a
return value. However, we now support all kinds of hardware that can
fail to set a line value: I2C, SPI, USB (hot-unpluggable chips), etc.
I want to rework the GPIO subsystem to make these functions return int
and become able to indicate failures. Build-bot complained about my
series[1] and pointed at this driver after the interface for
gpiod_set_value_cansleep() changed in patch 1. This is why I want to
fix it, get it into my tree and then pick up the series.

Sorry for not explaining it in detail earlier.

Bart

[1] https://lore.kernel.org/linux-gpio/20250211-gpio-set-retval-v1-0-52d3d613d7d3@linaro.org/