mixer: use an enum for airmode

src/modules/mc_att_control/mc_att_control_params.c

@@ -569,14 +569,15 @@ PARAM_DEFINE_FLOAT(MC_DTERM_CUTOFF, 30.f);
  *
  * The air-mode enables the mixer to increase the total thrust of the multirotor
  * in order to keep attitude and rate control even at low and high throttle.
+ *
  * This function should be disabled during tuning as it will help the controller
- * to diverge if the closed-loop is unstable.
+ * to diverge if the closed-loop is unstable (i.e. the vehicle is not tuned yet).
  *
- * 0 = Disabled, 1 = Roll/Pitch, 2 = Roll/Pitch/Yaw
+ * Enabling air-mode for yaw requires the use of an arming switch.
  *
- * @min 0
- * @max 2
- * @decimal 0
+ * @value 0 Disabled
+ * @value 1 Roll/Pitch
+ * @value 2 Roll/Pitch/Yaw
  * @group Multicopter Attitude Control
  */
 PARAM_DEFINE_INT32(MC_AIRMODE, 0);

src/modules/px4iofirmware/mixer.cpp

@@ -259,7 +259,7 @@ mixer_tick(void)
 	/*
 	 * Update air-mode parameter
 	 */
-	mixer_group.set_airmode(REG_TO_BOOL(r_setup_airmode));
+	mixer_group.set_airmode((Mixer::Airmode)REG_TO_SIGNED(r_setup_airmode));
 
 
 	/*