linux-kernel - Re: [PATCH] gpiolib: fix linker errors when GPIOLIB is disabled

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Message-ID: <2403894.jE0xQCEvom@steina-w>
Date:   Tue, 17 Jan 2023 07:23:50 +0100
From:   Alexander Stein <alexander.stein@...tq-group.com>
To:     linus.walleij@...aro.org, brgl@...ev.pl,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pierluigi Passaro <pierluigi.p@...iscite.com>
Cc:     eran.m@...iscite.com, nate.d@...iscite.com,
        francesco.f@...iscite.com, pierluigi.p@...iscite.com,
        pierluigi.passaro@...il.com, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] gpiolib: fix linker errors when GPIOLIB is disabled

Hi,

Am Montag, 16. Januar 2023, 15:08:11 CET schrieb Pierluigi Passaro:
> Both the functions gpiochip_request_own_desc and
> gpiochip_free_own_desc are exported from
>     drivers/gpio/gpiolib.c
> but this file is compiled only when CONFIG_GPIOLIB is enabled.
> Move the protototypes under "#ifdef CONFIG_GPIOLIB" and provide
> reasonable definitions in the "#else" branch.
> 
> Signed-off-by: Pierluigi Passaro <pierluigi.p@...iscite.com>
> Reported-by: kernel test robot <lkp@...el.com>
> ---
>  include/linux/gpio/driver.h | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index 44783fc16125..ed77c6fc0beb 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -758,6 +758,8 @@ gpiochip_remove_pin_ranges(struct gpio_chip *gc)
> 
>  #endif /* CONFIG_PINCTRL */
> 
> +#ifdef CONFIG_GPIOLIB
> +
>  struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc,
>  					    unsigned int hwnum,
>  					    const char *label,
> @@ -765,8 +767,6 @@ struct gpio_desc *gpiochip_request_own_desc(struct
> gpio_chip *gc, enum gpiod_flags dflags);
>  void gpiochip_free_own_desc(struct gpio_desc *desc);
> 
> -#ifdef CONFIG_GPIOLIB
> -
>  /* lock/unlock as IRQ */
>  int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset);
>  void gpiochip_unlock_as_irq(struct gpio_chip *gc, unsigned int offset);
> @@ -776,6 +776,22 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc
> *desc);
> 
>  #else /* CONFIG_GPIOLIB */
> 
> +static inline struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip
> *gc, +					    unsigned int hwnum,
> +					    const char *label,
> +					    enum gpio_lookup_flags 
lflags,
> +					    enum gpiod_flags dflags)
> +{
> +	/* GPIO can never have been requested */
> +	WARN_ON(1);

This will raise the warning on each invocation. How about using 
WARN_ON_ONCE(1), or even WARN_ONCE("Kernel compiled without CONFIG_GPIOLIB 
support")?

> +	return ERR_PTR(-ENODEV);
> +}
> +
> +static inline void gpiochip_free_own_desc(struct gpio_desc *desc)
> +{
> +	WARN_ON(1);

Same as above.

Best regards,
Alexander

> +}
> +
>  static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
> {
>  	/* GPIO can never have been requested */