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

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Message-ID: <20201124050618.GA337876@x1>
Date:   Mon, 23 Nov 2020 21:06:18 -0800
From:   Drew Fustini <drew@...gleboard.org>
To:     Pawan Gupta <writetopawan@...il.com>
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 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.

Could you share your .config?

Thank you,
Drew