2015-11-30 17:30:43

by Jose Diaz de Grenu de Pedro

Subject: [PATCH v2] gpiolib: return 0 or 1 in gpiod_get_value*() functions

Commit 79a9becda894 moved the awareness of active low state
into the gpiod_get_value*() functions, but it only inverts the
GPIO's raw value when it is active low. If the GPIO is active
high, the gpiod_get_value*() functions return the raw value of
the register, which can be any positive value.

This patch does a double inversion when the GPIO is active high
to make sure either 0 or 1 is returned by these functions.

Signed-off-by: Jose Diaz de Grenu de Pedro <[email protected]>
Signed-off-by: Hector Palacios <[email protected]>
---
change in v2:
- add missing semicolon
---
drivers/gpio/gpiolib.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 50c4922fe53a..bd96f0457ba8 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1981,9 +1981,9 @@ int gpiod_get_value(const struct gpio_desc *desc)

value = _gpiod_get_raw_value(desc);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
- value = !value;
-
- return value;
+ return !value;
+ else
+ return !!value;
}
EXPORT_SYMBOL_GPL(gpiod_get_value);

@@ -2224,9 +2224,9 @@ int gpiod_get_value_cansleep(const struct gpio_desc *desc)

value = _gpiod_get_raw_value(desc);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
- value = !value;
-
- return value;
+ return !value;
+ else
+ return !!value;
}
EXPORT_SYMBOL_GPL(gpiod_get_value_cansleep);

--
2.6.3

2015-11-30 20:05:53

by Bjorn Andersson

Subject: Re: [PATCH v2] gpiolib: return 0 or 1 in gpiod_get_value*() functions

On Mon, Nov 30, 2015 at 9:30 AM, Jose Diaz de Grenu de Pedro
<[email protected]> wrote:
> Commit 79a9becda894 moved the awareness of active low state
> into the gpiod_get_value*() functions, but it only inverts the
> GPIO's raw value when it is active low. If the GPIO is active
> high, the gpiod_get_value*() functions return the raw value of
> the register, which can be any positive value.
>
> This patch does a double inversion when the GPIO is active high
> to make sure either 0 or 1 is returned by these functions.
>
> Signed-off-by: Jose Diaz de Grenu de Pedro <[email protected]>
> Signed-off-by: Hector Palacios <[email protected]>
> ---
> change in v2:
> - add missing semicolon
> ---
> drivers/gpio/gpiolib.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 50c4922fe53a..bd96f0457ba8 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1981,9 +1981,9 @@ int gpiod_get_value(const struct gpio_desc *desc)
>
> value = _gpiod_get_raw_value(desc);
> if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
> - value = !value;
> -
> - return value;
> + return !value;
> + else
> + return !!value;
> }
> EXPORT_SYMBOL_GPL(gpiod_get_value);

On linux-next (at least) _gpiod_get_raw_value() returns the following value:

value = value < 0 ? value : !!value;

So this should already be negative errno, 0 or 1.

Regards,
Bjorn

2015-12-10 16:54:04

by Linus Walleij

Subject: Re: [PATCH v2] gpiolib: return 0 or 1 in gpiod_get_value*() functions

On Mon, Nov 30, 2015 at 6:30 PM, Jose Diaz de Grenu de Pedro
<[email protected]> wrote:

> Commit 79a9becda894 moved the awareness of active low state
> into the gpiod_get_value*() functions, but it only inverts the
> GPIO's raw value when it is active low. If the GPIO is active
> high, the gpiod_get_value*() functions return the raw value of
> the register, which can be any positive value.

No, because:

static int _gpiod_get_raw_value(const struct gpio_desc *desc)
{
struct gpio_chip *chip;
int offset;
int value;

chip = desc->chip;
offset = gpio_chip_hwgpio(desc);
value = chip->get ? chip->get(chip, offset) : -EIO;
value = value < 0 ? value : !!value;
trace_gpio_value(desc_to_gpio(desc), 1, value);
return value;
}

This returns a negative error code or the value clamped to [0,1]

Yours,
Linus Walleij