gpio: remove const modifier from gpiod_get_direction()

Although gpiod_get_direction() can be considered side-effect free for
consumers, its internals involve setting or clearing bits in the
affected GPIO descriptor, for which we need to force-cast the const
descriptor variable to non-const. This could lead to incorrect behavior
if the compiler decides to optimize here, so remove this const
attribute. The intent is to make gpiod_get_direction() private anyway,
so it does not really matter.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 781fbed00fc3c6755a0c84364cbb396a5152116e..2ac1800b58bb7052032ecd23d3acf270a1deb132 100644 (file)
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -41,7 +41,7 @@ static DEFINE_MUTEX(sysfs_lock);
 static ssize_t gpio_direction_show(struct device *dev,
                struct device_attribute *attr, char *buf)
 {
-       const struct gpio_desc  *desc = dev_get_drvdata(dev);
+       struct gpio_desc        *desc = dev_get_drvdata(dev);
        ssize_t                 status;
 
        mutex_lock(&sysfs_lock);

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5619922ebf44f7c97d84a418aa63de8882ab8acf..0b271ef87c0917267b30c1ec883fd0170e31f2e0 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -148,7 +148,7 @@ static int gpiochip_find_base(int ngpio)
  *
  * This function may sleep if gpiod_cansleep() is true.
  */
-int gpiod_get_direction(const struct gpio_desc *desc)
+int gpiod_get_direction(struct gpio_desc *desc)
 {
        struct gpio_chip        *chip;
        unsigned                offset;
@@ -164,13 +164,11 @@ int gpiod_get_direction(const struct gpio_desc *desc)
        if (status > 0) {
                /* GPIOF_DIR_IN, or other positive */
                status = 1;
-               /* FLAG_IS_OUT is just a cache of the result of get_direction(),
-                * so it does not affect constness per se */
-               clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
+               clear_bit(FLAG_IS_OUT, &desc->flags);
        }
        if (status == 0) {
                /* GPIOF_DIR_OUT */
-               set_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
+               set_bit(FLAG_IS_OUT, &desc->flags);
        }
        return status;
 }

diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 83c0a61c605dbf390bd09493b6f5ce3e04099b5c..d54d158ca3271850a37873b875971b9785262de4 100644 (file)
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -66,7 +66,7 @@ __devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
                              unsigned int index, enum gpiod_flags flags);
 void devm_gpiod_put(struct device *dev, struct gpio_desc *desc);
 
-int gpiod_get_direction(const struct gpio_desc *desc);
+int gpiod_get_direction(struct gpio_desc *desc);
 int gpiod_direction_input(struct gpio_desc *desc);
 int gpiod_direction_output(struct gpio_desc *desc, int value);
 int gpiod_direction_output_raw(struct gpio_desc *desc, int value);