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gpio: remove const modifier from gpiod_get_direction()

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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>
This commit is contained in:
Alexandre Courbot 2014-11-25 17:16:31 +09:00 committed by Linus Walleij
parent 14e85c0e69
commit 8e53b0f190
3 changed files with 5 additions and 7 deletions
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2
drivers/gpio/gpiolib-sysfs.c
View File

@ -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);

8
drivers/gpio/gpiolib.c
View File

@ -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;
}

2
include/linux/gpio/consumer.h
View File

@ -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);