diff mbox series

Documentation: gpio: fix typo and unclear legacy API section

Message ID 20201122092548.61979-1-gnurou@gmail.com
State Accepted
Commit a0de695819f63b02645e0c1c8d493324c02b0eb0
Headers show
Series Documentation: gpio: fix typo and unclear legacy API section | expand

Commit Message

Alexandre Courbot Nov. 22, 2020, 9:25 a.m. UTC 
The "Interacting With the Legacy GPIO Subsystem" of the documentation
was unclear at best, and even included a sentence that seems to say the
opposite of what it should say about the lifetime of the return value of
the conversion functions.

Try to clarify things a bit and hopefully make that section more
readable.

Signed-off-by: Alexandre Courbot <gnurou@gmail.com>
---
 Documentation/driver-api/gpio/consumer.rst | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

Comments

Linus Walleij Dec. 4, 2020, 8:49 a.m. UTC | #1 
On Sun, Nov 22, 2020 at 10:26 AM Alexandre Courbot <gnurou@gmail.com> wrote:

> The "Interacting With the Legacy GPIO Subsystem" of the documentation

> was unclear at best, and even included a sentence that seems to say the

> opposite of what it should say about the lifetime of the return value of

> the conversion functions.

>

> Try to clarify things a bit and hopefully make that section more

> readable.

>

> Signed-off-by: Alexandre Courbot <gnurou@gmail.com>


Patch applied!

Thanks for fixing this up and thanks to Andy for coordinating with
the fine folks over at StackOverflow. I added the BugLink and
Andy's Reported-by.

Yours,
Linus Walleij
diff mbox series

Patch

diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst
index 423492d125b9..173e4c7b037d 100644
--- a/Documentation/driver-api/gpio/consumer.rst
+++ b/Documentation/driver-api/gpio/consumer.rst
@@ -440,18 +440,20 @@  For details refer to Documentation/firmware-guide/acpi/gpio-properties.rst
 
 Interacting With the Legacy GPIO Subsystem
 ==========================================
-Many kernel subsystems still handle GPIOs using the legacy integer-based
-interface. Although it is strongly encouraged to upgrade them to the safer
-descriptor-based API, the following two functions allow you to convert a GPIO
-descriptor into the GPIO integer namespace and vice-versa::
+Many kernel subsystems and drivers still handle GPIOs using the legacy
+integer-based interface. It is strongly recommended to update these to the new
+gpiod interface. For cases where both interfaces need to be used, the following
+two functions allow to convert a GPIO descriptor into the GPIO integer namespace
+and vice-versa::
 
 	int desc_to_gpio(const struct gpio_desc *desc)
 	struct gpio_desc *gpio_to_desc(unsigned gpio)
 
-The GPIO number returned by desc_to_gpio() can be safely used as long as the
-GPIO descriptor has not been freed. All the same, a GPIO number passed to
-gpio_to_desc() must have been properly acquired, and usage of the returned GPIO
-descriptor is only possible after the GPIO number has been released.
+The GPIO number returned by desc_to_gpio() can safely be used as a parameter of
+the gpio\_*() functions for as long as the GPIO descriptor `desc` is not freed.
+All the same, a GPIO number passed to gpio_to_desc() must first be properly
+acquired using e.g. gpio_request_one(), and the returned GPIO descriptor is only
+considered valid until that GPIO number is released using gpio_free().
 
 Freeing a GPIO obtained by one API with the other API is forbidden and an
 unchecked error.