AP_Mount: Don't set GIMBAL_DEVICE_FLAGS_YAW_IN_VEHICLE_FRAME if yaw i…

…s locked

libraries/AP_Mount/AP_Mount_Backend.cpp

@@ -857,12 +857,14 @@ uint16_t AP_Mount_Backend::get_gimbal_device_flags() const
         break;
     }
 
+    const uint16_t yaw_ef_flags = GIMBAL_DEVICE_FLAGS_YAW_IN_EARTH_FRAME | GIMBAL_DEVICE_FLAGS_YAW_LOCK;
+    const uint16_t yaw_bf_flags = GIMBAL_DEVICE_FLAGS_YAW_IN_VEHICLE_FRAME;
+
     const uint16_t flags = (get_mode() == MAV_MOUNT_MODE_RETRACT ? GIMBAL_DEVICE_FLAGS_RETRACT : 0) |
                            (get_mode() == MAV_MOUNT_MODE_NEUTRAL ? GIMBAL_DEVICE_FLAGS_NEUTRAL : 0) |
-                           GIMBAL_DEVICE_FLAGS_ROLL_LOCK | // roll angle is always earth-frame
-                           GIMBAL_DEVICE_FLAGS_PITCH_LOCK| // pitch angle is always earth-frame, yaw_angle is always body-frame
-                           GIMBAL_DEVICE_FLAGS_YAW_IN_VEHICLE_FRAME | // yaw angle is always in vehicle-frame
-                           (yaw_lock_state ? GIMBAL_DEVICE_FLAGS_YAW_LOCK : 0);
+                           GIMBAL_DEVICE_FLAGS_ROLL_LOCK  | // roll angle is always earth-frame
+                           GIMBAL_DEVICE_FLAGS_PITCH_LOCK | // pitch angle is always earth-frame
+                           (yaw_lock_state ? yaw_ef_flags : yaw_bf_flags); // yaw angle can be either earth-frame or body-frame
     return flags;
 }