Minor serial code cleanup

Marlin/src/HAL/AVR/MarlinSerial.cpp

@@ -566,7 +566,7 @@ ISR(SERIAL_REGNAME(USART, SERIAL_PORT, _UDRE_vect)) {
   MarlinSerial<MarlinSerialCfg<SERIAL_PORT>>::_tx_udr_empty_irq();
 }
 
-// Because of the template definition above, it's required to instantiate the template to have all method generated
+// Because of the template definition above, it's required to instantiate the template to have all methods generated
 template class MarlinSerial< MarlinSerialCfg<SERIAL_PORT> >;
 MSerialT customizedSerial1(MSerialT::HasEmergencyParser);
 

Marlin/src/core/serial.h

@@ -62,6 +62,7 @@ typedef int8_t serial_index_t;
 #define SERIAL_ALL 0x7F
 #if HAS_MULTI_SERIAL
   #define _PORT_REDIRECT(n,p)   REMEMBER(n,multiSerial.portMask,p)
+  #define _PORT_RESTORE(n,p)    RESTORE(n)
   #define SERIAL_ASSERT(P)      if(multiSerial.portMask!=(P)){ debugger(); }
   #ifdef SERIAL_CATCHALL
     typedef MultiSerial<decltype(MYSERIAL), decltype(SERIAL_CATCHALL), 0> SerialOutputT;
@@ -72,6 +73,7 @@ typedef int8_t serial_index_t;
   #define SERIAL_IMPL           multiSerial
 #else
   #define _PORT_REDIRECT(n,p)   NOOP
+  #define _PORT_RESTORE(n)      NOOP
   #define SERIAL_ASSERT(P)      NOOP
   #define SERIAL_IMPL           MYSERIAL0
 #endif
@@ -79,6 +81,7 @@ typedef int8_t serial_index_t;
 #define SERIAL_OUT(WHAT, V...)  (void)SERIAL_IMPL.WHAT(V)
 
 #define PORT_REDIRECT(p)        _PORT_REDIRECT(1,p)
+#define PORT_RESTORE()          _PORT_RESTORE(1)
 #define SERIAL_PORTMASK(P)      _BV(P)
 
 //

Marlin/src/gcode/host/M118.cpp

@@ -53,14 +53,10 @@ void GcodeSuite::M118() {
   }
 
   #if HAS_MULTI_SERIAL
-    const int8_t old_serial = multiSerial.portMask;
-    if (WITHIN(port, 0, NUM_SERIAL))
-      multiSerial.portMask = port ? _BV(port - 1) : SERIAL_ALL;
+    PORT_REDIRECT(WITHIN(port, 0, NUM_SERIAL) ? (port ? _BV(port - 1) : SERIAL_ALL) : multiSerial.portMask);
   #endif
 
   if (hasE) SERIAL_ECHO_START();
   if (hasA) SERIAL_ECHOPGM("//");
   SERIAL_ECHOLN(p);
-
-  TERN_(HAS_MULTI_SERIAL, multiSerial.portMask = old_serial);
 }

Marlin/src/libs/autoreport.h

@@ -42,8 +42,9 @@ struct AutoReporter {
     const millis_t ms = millis();
     if (ELAPSED(ms, next_report_ms)) {
       next_report_ms = ms + SEC_TO_MS(report_interval);
-      TERN_(HAS_MULTI_SERIAL, PORT_REDIRECT(report_port_mask));
+      PORT_REDIRECT(report_port_mask);
       Helper::report();
+      //PORT_RESTORE();
     }
   }
 };

docs/Serial.md

@@ -1,11 +1,10 @@
 # Serial port architecture in Marlin
 
-Marlin is targeting a pletora of different CPU architecture and platforms. Each of these platforms has its own serial interface.
+Marlin is targeting a plethora of different CPU architecture and platforms. Each of these platforms has its own serial interface.
 While many provide a Arduino-like Serial class, it's not all of them, and the differences in the existing API create a very complex brain teaser for writing code that works more or less on each platform.
 
 Moreover, many platform have intrinsic needs about serial port (like forwarding the output on multiple serial port, providing a *serial-like* telnet server, mixing USB-based serial port with SD card emulation) that are difficult to handle cleanly in the other platform serial logic.
 
-
 Starting with version `2.0.9`, Marlin provides a common interface for its serial needs.
 
 ## Common interface
@@ -16,7 +15,7 @@ Any implementation will need to follow this interface for being used transparent
 The implementation was written to prioritize performance over abstraction, so the base interface is not using virtual inheritance to avoid the cost of virtual dispatching while calling methods.
 Instead, the Curiously Recurring Template Pattern (**CRTP**) is used so that, upon compilation, the interface abstraction does not incur a performance cost.
 
-Because some platform do not follow the same interface, the missing method in the actual low-level implementation are detected via SFINAE and a wrapper is generated when such method are missing. See `CALL_IF_EXISTS` macro in `Marlin/src/core/macros.h` for the documentation of this technic.
+Because some platform do not follow the same interface, the missing method in the actual low-level implementation are detected via SFINAE and a wrapper is generated when such method are missing. See the `CALL_IF_EXISTS` macro in `Marlin/src/core/macros.h` for documentation of this technique.
 
 ## Composing the desired feature
 The different specificities for each architecture are provided by composing the serial type based on desired functionality.
@@ -32,7 +31,7 @@ Since all the types above are using CRTP, it's possible to combine them to get t
 This is easily done via type definition of the feature.
 
 For example, to present a serial interface that's outputting to 2 serial port, the first one being hooked at runtime and the second one connected to a runtime switchable telnet client, you'll declare the type to use as:
-```
+```cpp
 typedef MultiSerial< RuntimeSerial<Serial>, ConditionalSerial<TelnetClient> > Serial0Type;
 ```