Update G-code injection, sub-commands (#14418)

Marlin/src/Marlin.cpp

@@ -502,19 +502,16 @@ void manage_inactivity(const bool ignore_stepper_queue/*=false*/) {
   #endif
 
   #if HAS_HOME
-    // Check to see if we have to home, use poor man's debouncer
-    // ---------------------------------------------------------
-    static int homeDebounceCount = 0;   // poor man's debouncing count
-    const int HOME_DEBOUNCE_DELAY = 2500;
-    if (!IS_SD_PRINTING() && !READ(HOME_PIN)) {
-      if (!homeDebounceCount) {
-        queue.inject_P(PSTR("G28"));
+    // Handle a standalone HOME button
+    constexpr millis_t HOME_DEBOUNCE_DELAY = 1000UL;
+    static millis_t next_home_key_ms; // = 0
+    if (!IS_SD_PRINTING() && !READ(HOME_PIN)) { // HOME_PIN goes LOW when pressed
+      const millis_t ms = millis();
+      if (ELAPSED(ms, next_home_key_ms)) {
+        next_home_key_ms = ms + HOME_DEBOUNCE_DELAY;
         LCD_MESSAGEPGM(MSG_AUTO_HOME);
+        queue.enqueue_now_P(PSTR("G28"));
       }
-      if (homeDebounceCount < HOME_DEBOUNCE_DELAY)
-        homeDebounceCount++;
-      else
-        homeDebounceCount = 0;
     }
   #endif
 

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

@@ -966,7 +966,7 @@ G29_TYPE GcodeSuite::G29() {
     #ifdef Z_PROBE_END_SCRIPT
       if (DEBUGGING(LEVELING)) DEBUG_ECHOLNPAIR("Z Probe End Script: ", Z_PROBE_END_SCRIPT);
       planner.synchronize();
-      queue.inject_P(PSTR(Z_PROBE_END_SCRIPT));
+      process_subcommands_now_P(PSTR(Z_PROBE_END_SCRIPT));
     #endif
 
     // Auto Bed Leveling is complete! Enable if possible.