From f87da51b37a15d9671632018bef00b309f090589 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Sat, 18 Oct 2014 12:46:20 +1100
Subject: [PATCH] Plane: prevent calling jump_to_landing_sequence() too often

---
 ArduPlane/ArduPlane.pde | 14 ++++++++++++--
 ArduPlane/system.pde    |  3 +++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/ArduPlane/ArduPlane.pde b/ArduPlane/ArduPlane.pde
index 061eb9d7c8..194ff3fff0 100644
--- a/ArduPlane/ArduPlane.pde
+++ b/ArduPlane/ArduPlane.pde
@@ -546,6 +546,9 @@ static struct {
     // in FBWA taildragger takeoff mode
     bool fbwa_tdrag_takeoff_mode:1;
 
+    // have we checked for an auto-land?
+    bool checked_for_autoland:1;
+
     // Altitude threshold to complete a takeoff command in autonomous modes.  Centimeters
     int32_t takeoff_altitude_cm;
 
@@ -574,6 +577,7 @@ static struct {
     next_wp_no_crosstrack : true,
     no_crosstrack : true,
     fbwa_tdrag_takeoff_mode : false,
+    checked_for_autoland : false,
     takeoff_altitude_cm : 0,
     takeoff_pitch_cd : 0,
     highest_airspeed : 0,
@@ -1421,12 +1425,18 @@ static void update_navigation()
             
     case RTL:
         if (g.rtl_autoland && 
+            !auto_state.checked_for_autoland &&
             nav_controller->reached_loiter_target() && 
             labs(altitude_error_cm) < 1000) {
-            if (mission.jump_to_landing_sequence()) {
-                gcs_send_text_P(PSTR("Starting auto landing"));
+            // we've reached the RTL point, see if we have a landing sequence
+            if (!auto_state.checked_for_autoland &&
+                mission.jump_to_landing_sequence()) {
+                gcs_send_text_P(SEVERITY_LOW, PSTR("Starting auto landing"));
                 set_mode(AUTO);
             }
+            // prevent running the expensive jump_to_landing_sequence
+            // on every loop
+            auto_state.checked_for_autoland = true;
         }
         // fall through to LOITER
 
diff --git a/ArduPlane/system.pde b/ArduPlane/system.pde
index 66252d2682..723e237328 100644
--- a/ArduPlane/system.pde
+++ b/ArduPlane/system.pde
@@ -297,6 +297,9 @@ static void set_mode(enum FlightMode mode)
     // don't cross-track when starting a mission
     auto_state.next_wp_no_crosstrack = true;
 
+    // reset landing check
+    auto_state.checked_for_autoland = false;
+
     // zero locked course
     steer_state.locked_course_err = 0;