Blink the value for unhomed/unknown axes (#10670)

Marlin/src/lcd/dogm/status_screen_DOGM.h

   }
 }
 
-FORCE_INLINE void _draw_axis_label(const AxisEnum axis, const char* const pstr, const bool blink) {
+//
+// Before homing, blink '123' <-> '???'.
+// Homed but unknown... '123' <-> '   '.
+// Homed and known, display constantly.
+//
+FORCE_INLINE void _draw_axis_value(const AxisEnum axis, const char *value, const bool blink) {
   if (blink)
-    lcd_put_u8str_rom(pstr);
+    lcd_put_u8str(value);
   else {
     if (!axis_homed[axis])
-      lcd_put_wchar('?');
+      while (const char c = *value++) lcd_put_wchar(c <= '.' ? c : '?');
     else {
       #if DISABLED(HOME_AFTER_DEACTIVATE) && DISABLED(DISABLE_REDUCED_ACCURACY_WARNING)
         if (!axis_known_position[axis])
-          lcd_put_wchar(' ');
+          lcd_put_u8str_rom(axis == Z_AXIS ? PSTR("      ") : PSTR("    "));
         else
       #endif
-          lcd_put_u8str_rom(pstr);
+          lcd_put_u8str(value);
     }
   }
 }
     #define XYZ_FRAME_HEIGHT INFO_FONT_HEIGHT + 1
   #endif
 
-  // Before homing the axis letters are blinking 'X' <-> '?'.
-  // When axis is homed but axis_known_position is false the axis letters are blinking 'X' <-> ' '.
-  // When everything is ok you see a constant 'X'.
-
   static char xstring[5], ystring[5], zstring[7];
   #if ENABLED(FILAMENT_LCD_DISPLAY)
     static char wstring[5], mstring[4];
       #endif
 
       lcd_moveto(0 * XYZ_SPACING + X_LABEL_POS, XYZ_BASELINE);
-      _draw_axis_label(X_AXIS, PSTR(MSG_X), blink);
+      lcd_put_wchar('X');
       lcd_moveto(0 * XYZ_SPACING + X_VALUE_POS, XYZ_BASELINE);
-      lcd_put_u8str(xstring);
+      _draw_axis_value(X_AXIS, xstring, blink);
 
       lcd_moveto(1 * XYZ_SPACING + X_LABEL_POS, XYZ_BASELINE);
-      _draw_axis_label(Y_AXIS, PSTR(MSG_Y), blink);
+      lcd_put_wchar('Y');
       lcd_moveto(1 * XYZ_SPACING + X_VALUE_POS, XYZ_BASELINE);
-      lcd_put_u8str(ystring);
+      _draw_axis_value(Y_AXIS, ystring, blink);
 
       lcd_moveto(2 * XYZ_SPACING + X_LABEL_POS, XYZ_BASELINE);
-      _draw_axis_label(Z_AXIS, PSTR(MSG_Z), blink);
+      lcd_put_wchar('Z');
       lcd_moveto(2 * XYZ_SPACING + X_VALUE_POS, XYZ_BASELINE);
-      lcd_put_u8str(zstring);
+      _draw_axis_value(Z_AXIS, zstring, blink);
 
       #if DISABLED(XYZ_HOLLOW_FRAME)
         u8g.setColorIndex(1); // black on white

Marlin/src/lcd/ultralcd_impl_HD44780.h

   lcd_put_u8str_rom(PSTR(MSG_PLEASE_RESET));
 }
 
-FORCE_INLINE void _draw_axis_label(const AxisEnum axis, const char* const pstr, const bool blink) {
+//
+// Before homing, blink '123' <-> '???'.
+// Homed but unknown... '123' <-> '   '.
+// Homed and known, display constantly.
+//
+FORCE_INLINE void _draw_axis_value(const AxisEnum axis, const char *value, const bool blink) {
+  lcd_put_wchar('X' + uint8_t(axis));
   if (blink)
-    lcd_put_u8str_rom(pstr);
+    lcd_put_u8str(value);
   else {
     if (!axis_homed[axis])
-      lcd_put_wchar('?');
+      while (const char c = *value++) lcd_put_wchar(c <= '.' ? c : '?');
     else {
       #if DISABLED(HOME_AFTER_DEACTIVATE) && DISABLED(DISABLE_REDUCED_ACCURACY_WARNING)
         if (!axis_known_position[axis])
-          lcd_put_wchar(' ');
+          lcd_put_u8str_rom(axis == Z_AXIS ? PSTR("      ") : PSTR("    "));
         else
       #endif
-          lcd_put_u8str_rom(pstr);
+          lcd_put_u8str(value);
     }
   }
 }
         ), blink);
 
       #else // HOTENDS <= 2 && (HOTENDS <= 1 || !TEMP_SENSOR_BED)
-        // Before homing the axis letters are blinking 'X' <-> '?'.
-        // When axis is homed but axis_known_position is false the axis letters are blinking 'X' <-> ' '.
-        // When everything is ok you see a constant 'X'.
 
-        _draw_axis_label(X_AXIS, PSTR(MSG_X), blink);
-        lcd_put_u8str(ftostr4sign(LOGICAL_X_POSITION(current_position[X_AXIS])));
+        _draw_axis_value(X_AXIS, ftostr4sign(LOGICAL_X_POSITION(current_position[X_AXIS])), blink);
 
         lcd_put_wchar(' ');
 
-        _draw_axis_label(Y_AXIS, PSTR(MSG_Y), blink);
-        lcd_put_u8str(ftostr4sign(LOGICAL_Y_POSITION(current_position[Y_AXIS])));
+        _draw_axis_value(Y_AXIS, ftostr4sign(LOGICAL_Y_POSITION(current_position[Y_AXIS])), blink);
 
       #endif // HOTENDS <= 2 && (HOTENDS <= 1 || !TEMP_SENSOR_BED)
 
     #endif // LCD_WIDTH >= 20
 
     lcd_moveto(LCD_WIDTH - 8, 1);
-    _draw_axis_label(Z_AXIS, PSTR(MSG_Z), blink);
-    lcd_put_u8str(ftostr52sp(LOGICAL_Z_POSITION(current_position[Z_AXIS])));
+    _draw_axis_value(Z_AXIS, ftostr52sp(LOGICAL_Z_POSITION(current_position[Z_AXIS])), blink);
 
     #if HAS_LEVELING && !TEMP_SENSOR_BED
       lcd_put_wchar(planner.leveling_active || blink ? '_' : ' ');