diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index bc0c14da7162..fb1ecf8baa90 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -60,7 +60,9 @@ struct module;
  * @names: if set, must be an array of strings to use as alternative
  *      names for the GPIOs in this chip. Any entry in the array
  *      may be NULL if there is no alias for the GPIO, however the
- *      array must be @ngpio entries long.
+ *      array must be @ngpio entries long.  A name can include a single printk
+ *      format specifier for an unsigned int.  It is substituted by the actual
+ *      number of the gpio.
  *
  * A gpio_chip can help platforms abstract various sources of GPIOs so
  * they can all be accessed through a common programing interface.