4 files changed, 14 insertions, 25 deletions

diff --git a/src/serialport/qserialport.cpp b/src/serialport/qserialport.cpp
index 65fcfbb..4f9d180 100644
--- a/src/serialport/qserialport.cpp
+++ b/src/serialport/qserialport.cpp
@@ -1240,10 +1240,9 @@ qint64 QSerialPort::readBufferSize() const
 void QSerialPort::setReadBufferSize(qint64 size)
 {
     Q_D(QSerialPort);
-
-    if (d->readBufferMaxSize == size)
-        return;
     d->readBufferMaxSize = size;
+    if (isReadable())
+        d->startAsyncRead();
 }
 
 /*!
@@ -1429,21 +1428,9 @@ qint64 QSerialPort::readData(char *data, qint64 maxSize)
     Q_UNUSED(data);
     Q_UNUSED(maxSize);
 
-#if defined(Q_OS_WIN32)
-    // We need try to start async reading to read a remainder from a driver's queue
-    // in case we have a limited read buffer size. Because the read notification can
-    // be stalled since Windows do not re-triggered an EV_RXCHAR event if a driver's
-    // buffer has a remainder of data ready to read until a new data will be received.
-    Q_D(QSerialPort);
-    if (d->readBufferMaxSize || d->flowControl == QSerialPort::HardwareControl)
-        d->startAsyncRead();
-#elif defined(Q_OS_UNIX)
-    // We need try to re-trigger the read notification to read a remainder from a
-    // driver's queue in case we have a limited read buffer size.
-    Q_D(QSerialPort);
-    if (d->readBufferMaxSize && !d->isReadNotificationEnabled())
-        d->setReadNotificationEnabled(true);
-#endif
+    // In any case we need to start the notifications if they were
+    // disabled by the read handler. If enabled, next call does nothing.
+    d_func()->startAsyncRead();
 
     // return 0 indicating there may be more data in the future
     return qint64(0);
diff --git a/src/serialport/qserialport_p.h b/src/serialport/qserialport_p.h
index a81cc4b..a742e0f 100644
--- a/src/serialport/qserialport_p.h
+++ b/src/serialport/qserialport_p.h
@@ -175,6 +175,8 @@ public:
     bool settingsRestoredOnClose;
     bool isBreakEnabled;
 
+    bool startAsyncRead();
+
 #if defined(Q_OS_WIN32)
 
     bool setDcb(DCB *dcb);
@@ -188,7 +190,6 @@ public:
     bool completeAsyncWrite(qint64 bytesTransferred);
 
     bool startAsyncCommunication();
-    bool startAsyncRead();
     bool _q_startAsyncWrite();
     void _q_notified(DWORD numberOfBytes, DWORD errorCode, OVERLAPPED *overlapped);
 
diff --git a/src/serialport/qserialport_unix.cpp b/src/serialport/qserialport_unix.cpp
index 0c79b47..544658c 100644
--- a/src/serialport/qserialport_unix.cpp
+++ b/src/serialport/qserialport_unix.cpp
@@ -763,6 +763,12 @@ bool QSerialPortPrivate::setFlowControl(QSerialPort::FlowControl flowControl)
     return setTermios(&tio);
 }
 
+bool QSerialPortPrivate::startAsyncRead()
+{
+    setReadNotificationEnabled(true);
+    return true;
+}
+
 bool QSerialPortPrivate::readNotification()
 {
     Q_Q(QSerialPort);
@@ -798,10 +804,6 @@ bool QSerialPortPrivate::readNotification()
 
     newBytes = buffer.size() - newBytes;
 
-    // If read buffer is full, disable the read port notifier.
-    if (readBufferMaxSize && buffer.size() == readBufferMaxSize)
-        setReadNotificationEnabled(false);
-
     // only emit readyRead() when not recursing, and only if there is data available
     const bool hasData = newBytes > 0;
 
diff --git a/src/serialport/qserialport_win.cpp b/src/serialport/qserialport_win.cpp
index 67c68ee..8ca2be9 100644
--- a/src/serialport/qserialport_win.cpp
+++ b/src/serialport/qserialport_win.cpp
@@ -484,8 +484,7 @@ bool QSerialPortPrivate::completeAsyncRead(qint64 bytesTransferred)
     if (bytesTransferred == QSERIALPORT_BUFFERSIZE
             || queuedBytesCount(QSerialPort::Input) > 0) {
         result = startAsyncRead();
-    } else if (readBufferMaxSize == 0
-               || readBufferMaxSize > buffer.size()) {
+    } else {
         result = startAsyncCommunication();
     }