simple-api: improve documentation

Mention the meaning of a positive value returned from the polling
callback of the simple event loop routines.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>

diff --git a/include/gpiod.h b/include/gpiod.h
index 7ef3ce436fa69eefea9e3afa9ffd4c8889eb3ed6..264c403e6ca99261b1efd28cbf37c8b069c0479e 100644 (file)
--- a/include/gpiod.h
+++ b/include/gpiod.h
@@ -168,6 +168,9 @@ typedef int (*gpiod_simple_event_handle_cb)(int, unsigned int,
 
 /**
  * @brief Return status values that the simple event poll callback can return.
+ *
+ * Positive value returned from the polling callback indicates the number of
+ * events that occurred on the set of monitored lines.
  */
 enum {
        GPIOD_SIMPLE_EVENT_POLL_RET_STOP = -2,