linux-kernel - Re: [PATCH] pinctrl: core: Fix unused variable build warnings

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Date:   Mon, 23 Nov 2020 23:51:29 -0800
From:   Pawan Gupta <writetopawan@...il.com>
To:     Drew Fustini <drew@...gleboard.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: core: Fix unused variable build warnings

On Mon, Nov 23, 2020 at 09:06:18PM -0800, Drew Fustini wrote:
> On Mon, Nov 23, 2020 at 02:33:33PM -0800, Pawan Gupta wrote:
> > A recent commit f1b206cf7c57 ("pinctrl: core: print gpio in pins debugfs
> > file") added build warnings when CONFIG_GPIOLIB=n. Offcourse the kernel
> > fails to build when warnings are treated as errors. Below is the error
> > message:
> > 
> >   $ make CFLAGS_KERNEL+=-Werror
> > 
> >   drivers/pinctrl/core.c: In function ‘pinctrl_pins_show’:
> >   drivers/pinctrl/core.c:1607:20: error: unused variable ‘chip’ [-Werror=unused-variable]
> >    1607 |  struct gpio_chip *chip;
> >         |                    ^~~~
> >   drivers/pinctrl/core.c:1606:15: error: unused variable ‘gpio_num’ [-Werror=unused-variable]
> >    1606 |  unsigned int gpio_num;
> >         |               ^~~~~~~~
> >   drivers/pinctrl/core.c:1605:29: error: unused variable ‘range’ [-Werror=unused-variable]
> >    1605 |  struct pinctrl_gpio_range *range;
> >         |                             ^~~~~
> >   cc1: all warnings being treated as errors
> > 
> > These variables are only used inside #ifdef CONFIG_GPIOLIB, fix the
> > build warnings by wrapping the definition inside the config.
> > 
> > Fixes: f1b206cf7c57 ("pinctrl: core: print gpio in pins debugfs file")
> > Signed-off-by: Pawan Gupta <writetopawan@...il.com>
> > ---
> >  drivers/pinctrl/core.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
> > index 3663d87f51a0..1bb371a5cf8d 100644
> > --- a/drivers/pinctrl/core.c
> > +++ b/drivers/pinctrl/core.c
> > @@ -1602,10 +1602,11 @@ static int pinctrl_pins_show(struct seq_file *s, void *what)
> >  	struct pinctrl_dev *pctldev = s->private;
> >  	const struct pinctrl_ops *ops = pctldev->desc->pctlops;
> >  	unsigned i, pin;
> > +#ifdef CONFIG_GPIOLIB
> >  	struct pinctrl_gpio_range *range;
> >  	unsigned int gpio_num;
> >  	struct gpio_chip *chip;
> > -
> > +#endif
> >  	seq_printf(s, "registered pins: %d\n", pctldev->desc->npins);
> >  
> >  	mutex_lock(&pctldev->mutex);
> > -- 
> > 2.21.3
> > 
> 
> Thanks for pointing this out.  I don't have any systems where I build
> without CONFIG_GPIOLIB so I missed this.
> 
> I'm having trouble figuring out a .config that will reproduce this.  I
> tried tinyconfig but it compiled clean.

Just setting CONFIG_GPIOLIB=n via menuconfig is not an option?  Have you
tried x86?

> Could you share your .config?

Attaching the .config that reproduces the build warning.

Thanks,
Pawan

View attachment ".config" of type "text/plain" (173341 bytes)