path: root/Documentation/gpio
diff options
authorAlexandre Courbot <acourbot@nvidia.com>2013-12-11 11:32:28 +0900
committerLinus Walleij <linus.walleij@linaro.org>2013-12-12 19:33:59 +0100
commit2a3cf6a3599e901528d3e0025a1bd0722a8d3575 (patch)
tree67bb549dbb30bf8a0a40395176aac02466a25c23 /Documentation/gpio
parent3b31d0eca5fd8d7d485c7cb7319a5cd6a3207726 (diff)
gpiolib: return -ENOENT if no GPIO mapping exists
Some devices drivers make use of optional GPIO parameters. For such drivers, it is important to discriminate between the case where no GPIO mapping has been defined for the function they are requesting, and the case where a mapping exists but an error occured while resolving it or when acquiring the GPIO. This patch changes the family of gpiod_get() functions such that they will return -ENOENT if and only if no GPIO mapping is defined for the requested function. Other error codes are used when an actual error occured during the GPIO resolution. Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation/gpio')
1 files changed, 5 insertions, 1 deletions
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 07c74a3765a0..e42f77d8d4ca 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -38,7 +38,11 @@ device that displays digits), an additional index argument can be specified:
const char *con_id, unsigned int idx)
Both functions return either a valid GPIO descriptor, or an error code checkable
-with IS_ERR(). They will never return a NULL pointer.
+with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
+if and only if no GPIO has been assigned to the device/function/index triplet,
+other error codes are used for cases where a GPIO has been assigned but an error
+occured while trying to acquire it. This is useful to discriminate between mere
+errors and an absence of GPIO for optional GPIO parameters.
Device-managed variants of these functions are also defined:

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