🩹 Fix Extensible MMU for >8 colors (#25772)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/MarlinCore.cpp

@@ -676,28 +676,9 @@ inline void manage_inactivity(const bool no_stepper_sleep=false) {
       && ELAPSED(ms, gcode.previous_move_ms + SEC_TO_MS(EXTRUDER_RUNOUT_SECONDS))
       && !planner.has_blocks_queued()
     ) {
-      #if HAS_SWITCHING_EXTRUDER
+      const int8_t e_stepper = TERN(HAS_SWITCHING_EXTRUDER, active_extruder >> 1, active_extruder);
-        bool oldstatus;
+      const bool e_off = !stepper.AXIS_IS_ENABLED(E_AXIS, e_stepper);
-        switch (active_extruder) {
+      if (e_off) stepper.ENABLE_EXTRUDER(e_stepper);
-          default: oldstatus = stepper.AXIS_IS_ENABLED(E_AXIS, 0); stepper.ENABLE_EXTRUDER(0); break;
-          #if E_STEPPERS > 1
-            case 2: case 3: oldstatus = stepper.AXIS_IS_ENABLED(E_AXIS, 1); stepper.ENABLE_EXTRUDER(1); break;
-            #if E_STEPPERS > 2
-              case 4: case 5: oldstatus = stepper.AXIS_IS_ENABLED(E_AXIS, 2); stepper.ENABLE_EXTRUDER(2); break;
-              #if E_STEPPERS > 3
-                case 6: case 7: oldstatus = stepper.AXIS_IS_ENABLED(E_AXIS, 3); stepper.ENABLE_EXTRUDER(3); break;
-              #endif // E_STEPPERS > 3
-            #endif // E_STEPPERS > 2
-          #endif // E_STEPPERS > 1
-        }
-      #else // !HAS_SWITCHING_EXTRUDER
-        bool oldstatus;
-        switch (active_extruder) {
-          default:
-          #define _CASE_EN(N) case N: oldstatus = stepper.AXIS_IS_ENABLED(E_AXIS, N); stepper.ENABLE_EXTRUDER(N); break;
-          REPEAT(E_STEPPERS, _CASE_EN);
-        }
-      #endif
 
       const float olde = current_position.e;
       current_position.e += EXTRUDER_RUNOUT_EXTRUDE;
@@ -706,22 +687,7 @@ inline void manage_inactivity(const bool no_stepper_sleep=false) {
       planner.set_e_position_mm(olde);
       planner.synchronize();
 
-      #if HAS_SWITCHING_EXTRUDER
+      if (e_off) stepper.DISABLE_EXTRUDER(e_stepper);
-        switch (active_extruder) {
-          default: if (oldstatus) stepper.ENABLE_EXTRUDER(0); else stepper.DISABLE_EXTRUDER(0); break;
-          #if E_STEPPERS > 1
-            case 2: case 3: if (oldstatus) stepper.ENABLE_EXTRUDER(1); else stepper.DISABLE_EXTRUDER(1); break;
-            #if E_STEPPERS > 2
-              case 4: case 5: if (oldstatus) stepper.ENABLE_EXTRUDER(2); else stepper.DISABLE_EXTRUDER(2); break;
-            #endif // E_STEPPERS > 2
-          #endif // E_STEPPERS > 1
-        }
-      #else // !HAS_SWITCHING_EXTRUDER
-        switch (active_extruder) {
-          #define _CASE_RESTORE(N) case N: if (oldstatus) stepper.ENABLE_EXTRUDER(N); else stepper.DISABLE_EXTRUDER(N); break;
-          REPEAT(E_STEPPERS, _CASE_RESTORE);
-        }
-      #endif // !HAS_SWITCHING_EXTRUDER
 
       gcode.reset_stepper_timeout(ms);
     }

Marlin/src/gcode/control/M17_M18_M84.cpp

@@ -71,7 +71,7 @@ void do_enable(const stepper_flags_t to_enable) {
 
   if (!shall_enable) return;    // All specified axes already enabled?
 
-  ena_mask_t also_enabled = 0;    // Track steppers enabled due to overlap
+  ena_mask_t also_enabled = 0;  // Track steppers enabled due to overlap
 
   // Enable all flagged axes
   LOOP_NUM_AXES(a) {

Marlin/src/module/stepper.h

@@ -255,8 +255,19 @@
 // This does not account for the possibility of multi-stepping.
 #define MIN_STEP_ISR_FREQUENCY (MAX_STEP_ISR_FREQUENCY_1X >> 1)
 
+// TODO: Review and ensure proper handling for special E axes with commands like M17/M18, stepper timeout, etc.
+#if ENABLED(MIXING_EXTRUDER)
+  #define E_STATES EXTRUDERS  // All steppers are set together for each mixer. (Currently limited to 1.)
+#elif HAS_SWITCHING_EXTRUDER
+  #define E_STATES E_STEPPERS // One stepper for every two EXTRUDERS. The last extruder can be non-switching.
+#elif HAS_PRUSA_MMU2
+  #define E_STATES E_STEPPERS // One E stepper shared with all EXTRUDERS, so setting any only sets one.
+#else
+  #define E_STATES E_STEPPERS // One stepper for each extruder, so each can be disabled individually.
+#endif
+
 // Number of axes that could be enabled/disabled. Dual/multiple steppers are combined.
-#define ENABLE_COUNT (NUM_AXES + E_STEPPERS)
+#define ENABLE_COUNT (NUM_AXES + E_STATES)
 typedef bits_t(ENABLE_COUNT) ena_mask_t;
 
 // Axis flags type, for enabled state or other simple state
@@ -265,8 +276,8 @@ typedef struct {
     ena_mask_t bits;
     struct {
       bool NUM_AXIS_LIST(X:1, Y:1, Z:1, I:1, J:1, K:1, U:1, V:1, W:1);
-      #if HAS_EXTRUDERS
+      #if E_STATES
-        bool LIST_N(EXTRUDERS, E0:1, E1:1, E2:1, E3:1, E4:1, E5:1, E6:1, E7:1);
+        bool LIST_N(E_STATES, E0:1, E1:1, E2:1, E3:1, E4:1, E5:1, E6:1, E7:1);
       #endif
     };
   };