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authorMark Brown <broonie@kernel.org>2020-12-28 17:16:53 +0300
committerMark Brown <broonie@kernel.org>2020-12-28 17:16:53 +0300
commitf81325a05e9317f09a2e4ec57a52e4e49eb42b54 (patch)
treea5a91589c9ef8e212f2899f1462cfb5c3f0130ef /Documentation/driver-api/gpio/consumer.rst
parent671ee4db952449acde126965bf76817a3159040d (diff)
parent5c8fe583cce542aa0b84adc939ce85293de36e5e (diff)
downloadlinux-f81325a05e9317f09a2e4ec57a52e4e49eb42b54.tar.xz
Merge tag 'v5.11-rc1' into asoc-5.11
Linux 5.11-rc1
Diffstat (limited to 'Documentation/driver-api/gpio/consumer.rst')
-rw-r--r--Documentation/driver-api/gpio/consumer.rst18
1 files changed, 10 insertions, 8 deletions
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.