linux-kernel - Re: [PATCH 2/5] powerpc: 83xx/gpio: use new line value setter callbacks

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Message-ID: <CAMRc=MesdgXAivzDnm1RW-jcxs_5goZiyKvK0-JLwqDv=9F6LQ@mail.gmail.com>
Date: Wed, 30 Apr 2025 19:37:14 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Madhavan Srinivasan <maddy@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, 
	Nicholas Piggin <npiggin@...il.com>, Naveen N Rao <naveen@...nel.org>, 
	Linus Walleij <linus.walleij@...aro.org>, Anatolij Gustschin <agust@...x.de>, linuxppc-dev@...ts.ozlabs.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 2/5] powerpc: 83xx/gpio: use new line value setter callbacks

On Wed, Apr 30, 2025 at 7:33 PM Christophe Leroy
<christophe.leroy@...roup.eu> wrote:
>
>
>
> Le 08/04/2025 à 09:21, Bartosz Golaszewski a écrit :
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > struct gpio_chip now has callbacks for setting line values that return
> > an integer, allowing to indicate failures. Convert the driver to using
> > them.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > ---
> >   arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
> > index 4d8fa9ed1a67..d4ba6dbb86b2 100644
> > --- a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
> > +++ b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
> > @@ -92,7 +92,7 @@ static void mcu_power_off(void)
> >       mutex_unlock(&mcu->lock);
> >   }
> >
> > -static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> > +static int mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> >   {
> >       struct mcu *mcu = gpiochip_get_data(gc);
> >       u8 bit = 1 << (4 + gpio);
> > @@ -105,6 +105,8 @@ static void mcu_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> >
> >       i2c_smbus_write_byte_data(mcu->client, MCU_REG_CTRL, mcu->reg_ctrl);
> >       mutex_unlock(&mcu->lock);
> > +
> > +     return 0;
>
> i2c_smbus_write_byte_data() can fail, why not return the value returned
> by i2c_smbus_write_byte_data() ?
>

The calls to i2c_smbus_write_byte_data() in this driver are
universally not checked. I cannot test it and wasn't sure if that's on
purpose so I decided to stay safe. Someone who has access to this
platform could potentially fix it across the file.

Bartosz

> >   }
> >
> >   static int mcu_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
> > @@ -123,7 +125,7 @@ static int mcu_gpiochip_add(struct mcu *mcu)
> >       gc->can_sleep = 1;
> >       gc->ngpio = MCU_NUM_GPIO;
> >       gc->base = -1;
> > -     gc->set = mcu_gpio_set;
> > +     gc->set_rv = mcu_gpio_set;
> >       gc->direction_output = mcu_gpio_dir_out;
> >       gc->parent = dev;
> >
> >
>