Update/correct some comments

drivers/input/Kconfig

@@ -347,8 +347,9 @@ config AJOYSTICK
 	---help---
 		Enable standard analog joystick upper half driver.  An analog
 		joystick refers to a joystick that provides position data as an
-		integer value that might have been obtained through DACs.
-		Discrete button inputs are also supported.
+		integer value that might have been obtained through Analog-
+		to-Digital Conversion (ADC).  The analog positional data may also
+		be accompanied by discrete button data.
 
 if AJOYSTICK
 

drivers/input/ajoystick.c

@@ -33,6 +33,17 @@
  *
  ****************************************************************************/
 
+/* This file provides a driver for a standard analog joystick device.  An
+ * analog joystick refers to a joystick that provides X/Y positional data as
+ * integer values such as might be provides by Analog-to-Digital Conversion
+ * (ADC).  The analog positional data may also be accompanied by discrete
+ * button data.
+ *
+ * The analog joystick driver exports a standard character driver
+ * interface. By convention, the analog joystick is registered as an input
+ * device at /dev/ajoyN where N uniquely identifies the driver instance.
+ */
+
 /****************************************************************************
  * Included Files
  ****************************************************************************/

drivers/input/djoystick.c

@@ -33,6 +33,17 @@
  *
  ****************************************************************************/
 
+/* This file provides a driver for a standard discrete joystick device.  A
+ * discrete joystick refers to a joystick that could be implemented entirely
+ * with GPIO input pins.  So up, down, left, and right are all discrete
+ * values like buttons (as opposed to integer values like you might obtain
+ * from an analog joystick).
+ *
+ * The discrete joystick driver exports a standard character driver
+ * interface. By convention, the discrete joystick is registered as an input
+ * device at /dev/djoyN where N uniquely identifies the driver instance.
+ */
+
 /****************************************************************************
  * Included Files
  ****************************************************************************/

include/nuttx/input/ajoystick.h

@@ -35,8 +35,9 @@
 
 /* This header file provides definition for a standard analog joystick
  * interface.  An analog joystick refers to a joystick that provides X/Y
- * positional data as integer values such as might be provides by DACs.
- * The analog positional data may be accompanied by discrete button data.
+ * positional data as integer values such as might be provides by Analog-
+ * to-Digital Conversion (ADC).  The analog positional data may also be
+ * accompanied by discrete button data.
  *
  * The analog joystick driver exports a standard character driver
  * interface. By convention, the analog joystick is registered as an input
@@ -109,7 +110,9 @@
  *
  * 1) The read() method will always return a single value of size
  *    struct ajoy_sample_s represent the current joystick positional and the
- *    state of all joystick buttons. read() never blocks.
+ *    state of all joystick buttons. read() never blocks.  X an Y position
+ *    data is raw converted data.  Zeroing and scaling must be performed by
+ *    the application.
  * 2) The poll() method can be used to notify a client if there is a change
  *    in any of the joystick button inputs.  This feature, of course,
  *    depends upon interrupt GPIO support from the platform.  NOTE: that