[PATCH] gpio: remove less important #ifdef around declarations

[PATCH] gpio: remove less important #ifdef around declarations

[Masahiro Yamada]

The whole struct/function declarations in this header are surrounded
by #ifdef.

As far as I understood, the motivation of doing so is probably to break
the build earlier if a driver misses to select or depend on correct
CONFIG options in Kconfig.

Since commit 94bed2a9c4ae ("Add -Werror-implicit-function-declaration")
no one cannot call functions that have not been declared.

So, I see some benefit in doing this in the cost of uglier headers.

In reality, it would not be so easy to catch missed 'select' or
'depends on' because GPIOLIB, GPIOLIB_IRQCHIP etc. are already selected
by someone else eventually. So, this kind of error, if any, will be
caught by randconfig bots.

In summary, I am not a big fan of cluttered #ifdef nesting, and this
does not matter for normal developers. The code readability wins.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

FYI,
If you want replace the commit log of the pinctrl variant,
the better log is available:
https://lkml.org/lkml/2019/6/26/1344

 include/linux/gpio/driver.h | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index a1d273c96016..845d657f2431 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -19,9 +19,6 @@ struct gpio_device;
 struct module;
 enum gpiod_flags;
 
-#ifdef CONFIG_GPIOLIB
-
-#ifdef CONFIG_GPIOLIB_IRQCHIP
 /**
  * struct gpio_irq_chip - GPIO interrupt controller
  */
@@ -167,7 +164,6 @@ struct gpio_irq_chip {
 	 */
 	void		(*irq_disable)(struct irq_data *data);
 };
-#endif
 
 /**
  * struct gpio_chip - abstract a GPIO controller
@@ -445,16 +441,12 @@ bool gpiochip_line_is_valid(const struct gpio_chip *chip, unsigned int offset);
 /* get driver data */
 void *gpiochip_get_data(struct gpio_chip *chip);
 
-struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
-
 struct bgpio_pdata {
 	const char *label;
 	int base;
 	int ngpio;
 };
 
-#if IS_ENABLED(CONFIG_GPIO_GENERIC)
-
 int bgpio_init(struct gpio_chip *gc, struct device *dev,
 	       unsigned long sz, void __iomem *dat, void __iomem *set,
 	       void __iomem *clr, void __iomem *dirout, void __iomem *dirin,
@@ -467,10 +459,6 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
 #define BGPIOF_READ_OUTPUT_REG_SET	BIT(4) /* reg_set stores output value */
 #define BGPIOF_NO_OUTPUT		BIT(5) /* only input */
 
-#endif
-
-#ifdef CONFIG_GPIOLIB_IRQCHIP
-
 int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
 		     irq_hw_number_t hwirq);
 void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq);
@@ -559,15 +547,11 @@ static inline int gpiochip_irqchip_add_nested(struct gpio_chip *gpiochip,
 }
 #endif /* CONFIG_LOCKDEP */
 
-#endif /* CONFIG_GPIOLIB_IRQCHIP */
-
 int gpiochip_generic_request(struct gpio_chip *chip, unsigned offset);
 void gpiochip_generic_free(struct gpio_chip *chip, unsigned offset);
 int gpiochip_generic_config(struct gpio_chip *chip, unsigned offset,
 			    unsigned long config);
 
-#ifdef CONFIG_PINCTRL
-
 /**
  * struct gpio_pin_range - pin range controlled by a gpio chip
  * @node: list for maintaining set of pin ranges, used internally
@@ -580,6 +564,8 @@ struct gpio_pin_range {
 	struct pinctrl_gpio_range range;
 };
 
+#ifdef CONFIG_PINCTRL
+
 int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
 			   unsigned int gpio_offset, unsigned int pin_offset,
 			   unsigned int npins);
@@ -620,6 +606,10 @@ void gpiochip_free_own_desc(struct gpio_desc *desc);
 void devprop_gpiochip_set_names(struct gpio_chip *chip,
 				const struct fwnode_handle *fwnode);
 
+#ifdef CONFIG_GPIOLIB
+
+struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc);
+
 #else /* CONFIG_GPIOLIB */
 
 static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
@@ -631,4 +621,4 @@ static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
 
 #endif /* CONFIG_GPIOLIB */
 
-#endif
+#endif /* __LINUX_GPIO_DRIVER_H */
-- 
2.17.1

Re: [PATCH] gpio: remove less important #ifdef around declarations

[Linus Walleij]

On Sun, Jul 7, 2019 at 4:31 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:

> The whole struct/function declarations in this header are surrounded
> by #ifdef.
>
> As far as I understood, the motivation of doing so is probably to break
> the build earlier if a driver misses to select or depend on correct
> CONFIG options in Kconfig.
>
> Since commit 94bed2a9c4ae ("Add -Werror-implicit-function-declaration")
> no one cannot call functions that have not been declared.
>
> So, I see some benefit in doing this in the cost of uglier headers.
>
> In reality, it would not be so easy to catch missed 'select' or
> 'depends on' because GPIOLIB, GPIOLIB_IRQCHIP etc. are already selected
> by someone else eventually. So, this kind of error, if any, will be
> caught by randconfig bots.
>
> In summary, I am not a big fan of cluttered #ifdef nesting, and this
> does not matter for normal developers. The code readability wins.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Hm I guess you're right.

This patch does not apply cleanly on v5.3-rc1, could you rebase it
and resend?

Yours,
Linus Walleij