USBH CDC setBaudrate() do nothing if baud is already matched

begin() will also change baudrate if mounted()

Author: hathach

src/arduino/cdc/Adafruit_USBH_CDC.cpp

@@ -42,6 +42,11 @@ void Adafruit_USBH_CDC::begin(unsigned long baudrate) {
   if (_baud == 0) {
     _baud = 115200; // default, backward compatible with previous API begin(0)
   }
+
+  // if already mounted, this will set baudrate
+  if (mounted()) {
+    setBaudrate(_baud);
+  }
 }
 
 void Adafruit_USBH_CDC::begin(unsigned long baudrate, uint16_t config) {
@@ -103,6 +108,11 @@ bool Adafruit_USBH_CDC::setBaudrate(uint32_t baudrate,
     return false;
   }
 
+  if (baud() == baudrate) {
+    // skip if already matched
+    return true;
+  }
+
   return tuh_cdc_set_baudrate(_idx, baudrate, complete_cb, user_data);
 }