Copter: do common gps arming checks first before moving on

ArduCopter/AP_Arming.cpp

@@ -417,15 +417,6 @@ bool AP_Arming_Copter::rc_calibration_checks(bool display_failure)
 // performs pre_arm gps related checks and returns true if passed
 bool AP_Arming_Copter::gps_checks(bool display_failure)
 {
-    // run mandatory gps checks first
-    if (!mandatory_gps_checks(display_failure)) {
-        AP_Notify::flags.pre_arm_gps_check = false;
-        return false;
-    }
-
-    // check if flight mode requires GPS
-    bool mode_requires_gps = copter.flightmode->requires_GPS();
-
     // check if fence requires GPS
     bool fence_requires_gps = false;
     #if AC_FENCE == ENABLED
@@ -433,6 +424,23 @@ bool AP_Arming_Copter::gps_checks(bool display_failure)
     fence_requires_gps = (copter.fence.get_enabled_fences() & (AC_FENCE_TYPE_CIRCLE | AC_FENCE_TYPE_POLYGON)) > 0;
     #endif
 
+    // check if flight mode requires GPS
+    bool mode_requires_gps = copter.flightmode->requires_GPS();
+
+    // call parent gps checks
+    if (mode_requires_gps || fence_requires_gps) {
+        if (!AP_Arming::gps_checks(display_failure)) {
+            AP_Notify::flags.pre_arm_gps_check = false;
+            return false;
+        }
+    }
+
+    // run mandatory gps checks first
+    if (!mandatory_gps_checks(display_failure)) {
+        AP_Notify::flags.pre_arm_gps_check = false;
+        return false;
+    }
+
     // return true if GPS is not required
     if (!mode_requires_gps && !fence_requires_gps) {
         AP_Notify::flags.pre_arm_gps_check = true;
@@ -452,12 +460,6 @@ bool AP_Arming_Copter::gps_checks(bool display_failure)
         return false;
     }
 
-    // call parent gps checks
-    if (!AP_Arming::gps_checks(display_failure)) {
-        AP_Notify::flags.pre_arm_gps_check = false;
-        return false;
-    }
-
     // if we got here all must be ok
     AP_Notify::flags.pre_arm_gps_check = true;
     return true;