2 files changed, 52 insertions, 1 deletions

diff --git a/src/serialport/qserialport_unix.cpp b/src/serialport/qserialport_unix.cpp
index 7c18d08..df8e9cb 100644
--- a/src/serialport/qserialport_unix.cpp
+++ b/src/serialport/qserialport_unix.cpp
@@ -395,7 +395,12 @@ bool QSerialPortPrivate::setBreakEnabled(bool set)
 
 qint64 QSerialPortPrivate::readData(char *data, qint64 maxSize)
 {
-    return readBuffer.read(data, maxSize);
+    const qint64 result = readBuffer.read(data, maxSize);
+    // 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.
+    if (d->readBufferMaxSize && result > 0 && !d->isReadNotificationEnabled())
+        d->setReadNotificationEnabled(true);
+    return result;
 }
 
 bool QSerialPortPrivate::waitForReadyRead(int msecs)
@@ -744,6 +749,7 @@ bool QSerialPortPrivate::readNotification()
         if (bytesToRead == 0) {
             // Buffer is full. User must read data from the buffer
             // before we can read more from the port.
+            setReadNotificationEnabled(false);
             return false;
         }
     }
diff --git a/tests/auto/qserialport/tst_qserialport.cpp b/tests/auto/qserialport/tst_qserialport.cpp
index 74eec3d..134c7d7 100644
--- a/tests/auto/qserialport/tst_qserialport.cpp
+++ b/tests/auto/qserialport/tst_qserialport.cpp
@@ -129,6 +129,8 @@ private slots:
     void asynchronousWriteByTimer_data();
     void asynchronousWriteByTimer();
 
+    void asyncReadWithLimitedReadBufferSize();
+
     void readBufferOverflow();
     void readAfterInputClear();
     void synchronousReadWriteAfterAsynchronousReadWrite();
@@ -807,6 +809,49 @@ void tst_QSerialPort::asynchronousWriteByTimer()
     QCOMPARE(receiverPort.readAll(), alphabetArray);
 }
 
+class AsyncReader2 : public QObject
+{
+    Q_OBJECT
+public:
+    explicit AsyncReader2(QSerialPort &port, const QByteArray &expectedData)
+        : serialPort(port), expectedData(expectedData)
+    {
+        connect(&serialPort, SIGNAL(readyRead()), this, SLOT(receive()));
+    }
+
+private slots:
+    void receive()
+    {
+        receivedData.append(serialPort.readAll());
+        if (receivedData == expectedData)
+            tst_QSerialPort::exitLoop();
+    }
+
+private:
+    QSerialPort &serialPort;
+    const QByteArray expectedData;
+    QByteArray receivedData;
+};
+
+void tst_QSerialPort::asyncReadWithLimitedReadBufferSize()
+{
+    QSerialPort senderPort(m_senderPortName);
+    QVERIFY(senderPort.open(QSerialPort::WriteOnly));
+
+    QSerialPort receiverPort(m_receiverPortName);
+    QVERIFY(receiverPort.open(QSerialPort::ReadOnly));
+
+    receiverPort.setReadBufferSize(1);
+    QCOMPARE(receiverPort.readBufferSize(), qint64(1));
+
+    AsyncReader2 reader(receiverPort, alphabetArray);
+
+    QCOMPARE(senderPort.write(alphabetArray), qint64(alphabetArray.size()));
+
+    enterLoop(1);
+    QVERIFY2(!timeout(), "Timed out when waiting for the read or write.");
+}
+
 void tst_QSerialPort::readBufferOverflow()
 {
     QSerialPort senderPort(m_senderPortName);