🚸 Use M600 for disabled MMU (#21865)

Marlin/src/MarlinCore.cpp

   (void)check_tool_sensor_stats(active_extruder, true);
 
   // Handle filament runout sensors
-  TERN_(HAS_FILAMENT_SENSOR, runout.run());
+  #if HAS_FILAMENT_SENSOR
+    if (TERN1(HAS_PRUSA_MMU2, !mmu2.enabled()))
+      runout.run();
+  #endif
 
   // Run HAL idle tasks
   TERN_(HAL_IDLETASK, HAL_idletask());

Marlin/src/feature/pause.h

 
 extern uint8_t did_pause_print;
 
-#if ENABLED(DUAL_X_CARRIAGE)
-  #define DXC_PARAMS , const int8_t DXC_ext=-1
-  #define DXC_ARGS   , const int8_t DXC_ext
-  #define DXC_PASS   , DXC_ext
-  #define DXC_SAY    , " dxc:", int(DXC_ext)
-#else
-  #define DXC_PARAMS
-  #define DXC_ARGS
-  #define DXC_PASS
-  #define DXC_SAY
-#endif
+#define DXC_PARAMS OPTARG(DUAL_X_CARRIAGE, const int8_t DXC_ext=-1)
+#define DXC_ARGS   OPTARG(DUAL_X_CARRIAGE, const int8_t DXC_ext)
+#define DXC_PASS   OPTARG(DUAL_X_CARRIAGE, DXC_ext)
+#define DXC_SAY    OPTARG(DUAL_X_CARRIAGE, " dxc:", int(DXC_ext))
 
 // Pause the print. If unload_length is set, do a Filament Unload
 bool pause_print(

Marlin/src/gcode/feature/pause/M600.cpp

   #include "../../../module/tool_change.h"
 #endif
 
-#if ENABLED(MMU2_MENUS)
-  #include "../../../lcd/menu/menu_mmu2.h"
+#if ENABLED(HAS_PRUSA_MMU2)
+  #include "../../../feature/mmu/mmu2.h"
+  #if ENABLED(MMU2_MENUS)
+    #include "../../../lcd/menu/menu_mmu2.h"
+  #endif
 #endif
 
 #if ENABLED(MIXING_EXTRUDER)
     }
   #endif
 
+  const bool standardM600 = TERN1(MMU2_MENUS, !mmu2.enabled());
+
   // Show initial "wait for start" message
-  #if DISABLED(MMU2_MENUS)
+  if (standardM600)
     ui.pause_show_message(PAUSE_MESSAGE_CHANGING, PAUSE_MODE_PAUSE_PRINT, target_extruder);
-  #endif
 
   #if ENABLED(HOME_BEFORE_FILAMENT_CHANGE)
     // If needed, home before parking for filament change
   #endif
 
   #if ENABLED(MMU2_MENUS)
-    // For MMU2 reset retract and load/unload values so they don't mess with MMU filament handling
-    constexpr float unload_length = 0.5f,
-                    slow_load_length = 0.0f,
-                    fast_load_length = 0.0f;
+    // For MMU2, when enabled, reset retract value so it doesn't mess with MMU filament handling
+    const float unload_length = standardM600 ? -ABS(parser.axisunitsval('U', E_AXIS, fc_settings[active_extruder].unload_length)) : 0.5f;
   #else
     // Unload filament
     const float unload_length = -ABS(parser.axisunitsval('U', E_AXIS, fc_settings[active_extruder].unload_length));
-    // Slow load filament
-    constexpr float slow_load_length = FILAMENT_CHANGE_SLOW_LOAD_LENGTH;
-    // Fast load filament
-    const float fast_load_length = ABS(parser.axisunitsval('L', E_AXIS, fc_settings[active_extruder].load_length));
   #endif
 
   const int beep_count = parser.intval('B', -1
   );
 
   if (pause_print(retract, park_point, true, unload_length DXC_PASS)) {
-    #if ENABLED(MMU2_MENUS)
-      mmu2_M600();
-      resume_print(slow_load_length, fast_load_length, 0, beep_count DXC_PASS);
-    #else
+    if (standardM600) {
       wait_for_confirmation(true, beep_count DXC_PASS);
-      resume_print(slow_load_length, fast_load_length, ADVANCED_PAUSE_PURGE_LENGTH,
-                   beep_count, (parser.seenval('R') ? parser.value_celsius() : 0) DXC_PASS);
-    #endif
+      resume_print(
+        FILAMENT_CHANGE_SLOW_LOAD_LENGTH,
+        ABS(parser.axisunitsval('L', E_AXIS, fc_settings[active_extruder].load_length)),
+        ADVANCED_PAUSE_PURGE_LENGTH,
+        beep_count,
+        parser.celsiusval('R')
+        DXC_PASS
+      );
+    }
+    else {
+      #if ENABLED(MMU2_MENUS)
+        mmu2_M600();
+        resume_print(0, 0, 0, beep_count, 0 DXC_PASS);
+      #endif
+    }
   }
 
   #if HAS_MULTI_EXTRUDER