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author | Mark Brown <broonie@kernel.org> | 2020-12-28 17:16:53 +0300 |
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committer | Mark Brown <broonie@kernel.org> | 2020-12-28 17:16:53 +0300 |
commit | f81325a05e9317f09a2e4ec57a52e4e49eb42b54 (patch) | |
tree | a5a91589c9ef8e212f2899f1462cfb5c3f0130ef /Documentation/driver-api/gpio/consumer.rst | |
parent | 671ee4db952449acde126965bf76817a3159040d (diff) | |
parent | 5c8fe583cce542aa0b84adc939ce85293de36e5e (diff) | |
download | linux-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.rst | 18 |
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. |