Add XON/XOFF options to example configs

Marlin/example_configurations/AlephObjects/TAZ4/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/AlephObjects/TAZ4/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/AliExpress/CL-260/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Anet/A6/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/Anet/A6/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Anet/A8/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/Anet/A8/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/BQ/Hephestos/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/BQ/Hephestos/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/BQ/Hephestos_2/Configuration.h

@@ -106,8 +106,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/BQ/Hephestos_2/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 32
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/BQ/WITBOX/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/BQ/WITBOX/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Cartesio/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/Cartesio/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Creality/CR-10/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/Felix/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Felix/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Felix/DUAL/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Folger Tech/i3-2020/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Folger Tech/i3-2020/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Geeetech/GT2560/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Geeetech/I3_Pro_X-GT2560/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Infitary/i3-M508/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Infitary/i3-M508/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Malyan/M150/Configuration.h

@@ -112,8 +112,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/Malyan/M150/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/RigidBot/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/RigidBot/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/SCARA/Configuration.h

@@ -137,8 +137,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/SCARA/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/TinyBoy2/Configuration.h

@@ -123,8 +123,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/TinyBoy2/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 64
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Velleman/K8200/Configuration.h

@@ -123,8 +123,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Velleman/K8200/Configuration_adv.h

@@ -753,6 +753,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 128
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Velleman/K8400/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/Velleman/K8400/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/Velleman/K8400/Dual-head/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/adafruit/ST7565/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration_adv.h

@@ -742,6 +742,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration_adv.h

@@ -742,6 +742,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/delta/generic/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/generic/Configuration_adv.h

@@ -742,6 +742,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/delta/kossel_mini/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/kossel_mini/Configuration_adv.h

@@ -742,6 +742,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/delta/kossel_pro/Configuration.h

@@ -111,8 +111,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/delta/kossel_pro/Configuration_adv.h

@@ -747,6 +747,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/delta/kossel_xl/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/delta/kossel_xl/Configuration_adv.h

@@ -742,6 +742,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/gCreate/gMax1.5+/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/gCreate/gMax1.5+/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 32
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/makibox/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/makibox/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/tvrrug/Round2/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 250000
 

Marlin/example_configurations/tvrrug/Round2/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410

Marlin/example_configurations/wt150/Configuration.h

@@ -107,8 +107,9 @@
  *
  * 250000 works in most cases, but you might try a lower speed if
  * you commonly experience drop-outs during host printing.
+ * You may try up to 1000000 to speed up SD file transfer.
  *
- * :[2400, 9600, 19200, 38400, 57600, 115200, 250000]
+ * :[2400, 9600, 19200, 38400, 57600, 115200, 250000, 500000, 1000000]
  */
 #define BAUDRATE 115200
 

Marlin/example_configurations/wt150/Configuration_adv.h

@@ -740,6 +740,28 @@
 // :[0, 2, 4, 8, 16, 32, 64, 128, 256]
 #define TX_BUFFER_SIZE 0
 
+// Host Receive Buffer Size
+// Without XON/XOFF flow control (see SERIAL_XON_XOFF below) 32 bytes should be enough.
+// To use flow control, set this buffer size to at least 1024 bytes.
+// :[0, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048]
+//#define RX_BUFFER_SIZE 1024
+
+#if RX_BUFFER_SIZE >= 1024
+  // Enable to have the controller send XON/XOFF control characters to
+  // the host to signal the RX buffer is becoming full.
+  //#define SERIAL_XON_XOFF
+#endif
+
+#if ENABLED(SDSUPPORT)
+  // Enable this option to collect and display the maximum
+  // RX queue usage after transferring a file to SD.
+  //#define SERIAL_STATS_MAX_RX_QUEUED
+
+  // Enable this option to collect and display the number
+  // of dropped bytes after a file transfer to SD.
+  //#define SERIAL_STATS_DROPPED_RX
+#endif
+
 // Enable an emergency-command parser to intercept certain commands as they
 // enter the serial receive buffer, so they cannot be blocked.
 // Currently handles M108, M112, M410