🐛 Fix M_State_grbl when G29 calls G28

Marlin/src/gcode/bedlevel/abl/G29.cpp

   #endif
 #endif
 
-#define G29_RETURN(b) return TERN_(G29_RETRY_AND_RECOVER, b)
+#define G29_RETURN(retry) do{ \
+  if (TERN(G29_RETRY_AND_RECOVER, !retry, true)) { \
+    TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_IDLE, false)); \
+  } \
+  return TERN_(G29_RETRY_AND_RECOVER, retry); \
+}while(0)
 
 // For manual probing values persist over multiple G29
 class G29_State {
 G29_TYPE GcodeSuite::G29() {
   DEBUG_SECTION(log_G29, "G29", DEBUGGING(LEVELING));
 
+  // Leveling state is persistent when done manually with multiple G29 commands
   TERN_(PROBE_MANUALLY, static) G29_State abl;
 
-  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_PROBE));
-
+  // Keep powered steppers from timing out
   reset_stepper_timeout();
 
+  // Q = Query leveling and G29 state
   const bool seenQ = EITHER(DEBUG_LEVELING_FEATURE, PROBE_MANUALLY) && parser.seen_test('Q');
 
   // G29 Q is also available if debugging
     if (DISABLED(PROBE_MANUALLY) && seenQ) G29_RETURN(false);
   #endif
 
+  // A = Abort manual probing
+  // C<bool> = Generate fake probe points (DEBUG_LEVELING_FEATURE)
   const bool seenA = TERN0(PROBE_MANUALLY, parser.seen_test('A')),
          no_action = seenA || seenQ,
               faux = ENABLED(DEBUG_LEVELING_FEATURE) && DISABLED(PROBE_MANUALLY) ? parser.boolval('C') : no_action;
 
-  if (!no_action && planner.leveling_active && parser.boolval('O')) { // Auto-level only if needed
+  // O = Don't level if leveling is already active
+  if (!no_action && planner.leveling_active && parser.boolval('O')) {
     if (DEBUGGING(LEVELING)) DEBUG_ECHOLNPGM("> Auto-level not needed, skip");
     G29_RETURN(false);
   }
   // Don't allow auto-leveling without homing first
   if (homing_needed_error()) G29_RETURN(false);
 
+  // 3-point leveling gets points from the probe class
   #if ENABLED(AUTO_BED_LEVELING_3POINT)
     vector_3 points[3];
     probe.get_three_points(points);
   #endif
 
+  // Storage for ABL Linear results
   #if ENABLED(AUTO_BED_LEVELING_LINEAR)
     struct linear_fit_data lsf_results;
   #endif
 
+  // Set and report "probing" state to host
+  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_PROBE, false));
+
   /**
    * On the initial G29 fetch command parameters.
    */
     if (!no_action) set_bed_leveling_enabled(false);
 
     // Deploy certain probes before starting probing
-    #if HAS_BED_PROBE
-      if (ENABLED(BLTOUCH))
-        do_z_clearance(Z_CLEARANCE_DEPLOY_PROBE);
-      else if (probe.deploy()) {
+    #if ENABLED(BLTOUCH)
+      do_z_clearance(Z_CLEARANCE_DEPLOY_PROBE);
+    #elif HAS_BED_PROBE
+      if (probe.deploy()) { // (returns true on deploy failure)
         set_bed_leveling_enabled(abl.reenable);
         G29_RETURN(false);
       }
         SERIAL_ECHOLNPGM("idle");
     }
 
+    // For 'A' or 'Q' exit with success state
     if (no_action) G29_RETURN(false);
 
     if (abl.abl_probe_index == 0) {
 
   report_current_position();
 
-  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_IDLE));
-
   G29_RETURN(isnan(abl.measured_z));
 
 }

Marlin/src/gcode/bedlevel/mbl/G29.cpp

     }
   #endif
 
-  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_PROBE));
-
   static int mbl_probe_index = -1;
 
   MeshLevelingState state = (MeshLevelingState)parser.byteval('S', (int8_t)MeshReport);
     return;
   }
 
+  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_PROBE));
+
   int8_t ix, iy;
   ix = iy = 0;
 

Marlin/src/gcode/calibrate/G28.cpp

 
   TERN_(LASER_MOVE_G28_OFF, cutter.set_inline_enabled(false));  // turn off laser
 
-  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_HOMING));
-
   #if ENABLED(DUAL_X_CARRIAGE)
     bool IDEX_saved_duplication_state = extruder_duplication_enabled;
     DualXMode IDEX_saved_mode = dual_x_carriage_mode;
     return;
   }
 
+  #if ENABLED(FULL_REPORT_TO_HOST_FEATURE)
+    const M_StateEnum old_grblstate = M_State_grbl;
+    set_and_report_grblstate(M_HOMING);
+  #endif
+
   TERN_(HAS_DWIN_E3V2_BASIC, DWIN_StartHoming());
   TERN_(EXTENSIBLE_UI, ExtUI::onHomingStart());
 
   if (ENABLED(NANODLP_Z_SYNC) && (doZ || ENABLED(NANODLP_ALL_AXIS)))
     SERIAL_ECHOLNPGM(STR_Z_MOVE_COMP);
 
-  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(M_IDLE));
+  TERN_(FULL_REPORT_TO_HOST_FEATURE, set_and_report_grblstate(old_grblstate));
 
   #if HAS_L64XX
     // Set L6470 absolute position registers to counts

Marlin/src/module/motion.h

   void report_current_position_moving();
 
   #if ENABLED(FULL_REPORT_TO_HOST_FEATURE)
-    inline void set_and_report_grblstate(const M_StateEnum state) {
-      M_State_grbl = state;
-      report_current_grblstate_moving();
+    inline void set_and_report_grblstate(const M_StateEnum state, const bool force=true) {
+      if (force || M_State_grbl != state) {
+        M_State_grbl = state;
+        report_current_grblstate_moving();
+      }
     }
   #endif