From c7df96114472b09ba4d109f59a90f9a307baf081 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Wed, 20 Apr 2016 13:01:58 -0700
Subject: [PATCH 1/2] Fix G92 so it only sets the plan position once

---
 Marlin/Marlin_main.cpp | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index ecd9f9e38..7f49d8b5b 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -1427,6 +1427,7 @@ inline void sync_plan_position() {
   #endif
   plan_set_position(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS]);
 }
+inline void sync_plan_position_e() { plan_set_e_position(current_position[E_AXIS]); }
 inline void set_current_to_destination() { memcpy(current_position, destination, sizeof(current_position)); }
 inline void set_destination_to_current() { memcpy(destination, current_position, sizeof(destination)); }
 
@@ -3642,8 +3643,9 @@ inline void gcode_G28() {
  * G92: Set current position to given X Y Z E
  */
 inline void gcode_G92() {
-  if (!code_seen(axis_codes[E_AXIS]))
-    st_synchronize();
+  bool didE = code_seen(axis_codes[E_AXIS]);
+
+  if (!didE) st_synchronize();
 
   bool didXYZ = false;
   for (int i = 0; i < NUM_AXIS; i++) {
@@ -3653,14 +3655,11 @@ inline void gcode_G92() {
 
       current_position[i] = v;
 
-      if (i == E_AXIS)
-        plan_set_e_position(v);
-      else {
+      if (i != E_AXIS) {
         position_shift[i] += v - p; // Offset the coordinate space
         update_software_endstops((AxisEnum)i);
-		  
         didXYZ = true;
-	  }
+      }
     }
   }
   if (didXYZ) {
@@ -3670,6 +3669,9 @@ inline void gcode_G92() {
       sync_plan_position();
     #endif
   }
+  else if (didE) {
+    sync_plan_position_e();
+  }
 }
 
 #if ENABLED(ULTIPANEL)

From 1caa2628da8cb2cfda3eb5e2f47ebe8183c8b267 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <sourcetree@thinkyhead.com>
Date: Wed, 20 Apr 2016 13:02:19 -0700
Subject: [PATCH 2/2] Use sync_plan_position_e function elsewhere

---
 Marlin/Marlin_main.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 7f49d8b5b..66e84843c 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -2321,7 +2321,7 @@ static void homeaxis(AxisEnum axis) {
 
       feedrate = retract_feedrate * 60;
       current_position[E_AXIS] += (swapping ? retract_length_swap : retract_length) / volumetric_multiplier[active_extruder];
-      plan_set_e_position(current_position[E_AXIS]);
+      sync_plan_position_e();
       prepare_move();
 
       if (retract_zlift > 0.01) {
@@ -2349,7 +2349,7 @@ static void homeaxis(AxisEnum axis) {
       feedrate = retract_recover_feedrate * 60;
       float move_e = swapping ? retract_length_swap + retract_recover_length_swap : retract_length + retract_recover_length;
       current_position[E_AXIS] -= move_e / volumetric_multiplier[active_extruder];
-      plan_set_e_position(current_position[E_AXIS]);
+      sync_plan_position_e();
       prepare_move();
     }
 
@@ -2440,7 +2440,7 @@ inline void gcode_G0_G1() {
         // Is this move an attempt to retract or recover?
         if ((echange < -MIN_RETRACT && !retracted[active_extruder]) || (echange > MIN_RETRACT && retracted[active_extruder])) {
           current_position[E_AXIS] = destination[E_AXIS]; // hide the slicer-generated retract/recover from calculations
-          plan_set_e_position(current_position[E_AXIS]);  // AND from the planner
+          sync_plan_position_e();  // AND from the planner
           retract(!retracted[active_extruder]);
           return;
         }
@@ -6108,7 +6108,7 @@ inline void gcode_M503() {
     #endif
 
     current_position[E_AXIS] = destination[E_AXIS]; //the long retract of L is compensated by manual filament feeding
-    plan_set_e_position(current_position[E_AXIS]);
+    sync_plan_position_e();
 
     RUNPLAN; //should do nothing