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-rw-r--r--Documentation/gpio/consumer.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 05676fdacfe3..912568baabb9 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -70,6 +70,12 @@ instead of -ENOENT if no GPIO has been assigned to the requested function:
unsigned int index,
enum gpiod_flags flags)
+Note that gpio_get*_optional() functions (and their managed variants), unlike
+the rest of gpiolib API, also return NULL when gpiolib support is disabled.
+This is helpful to driver authors, since they do not need to special case
+-ENOSYS return codes. System integrators should however be careful to enable
+gpiolib on systems that need it.
+
For a function using multiple GPIOs all of those can be obtained with one call:
struct gpio_descs *gpiod_get_array(struct device *dev,