alsa: Prevent buffer underrun errors when QIODevice has no data to read

Fixes: QTBUG-114900
Pick-to: 6.6 6.5
Change-Id: I093538ea4f1b4f9fdcf22d38343b4c8aff55a39d
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
(cherry picked from commit c39a9a4f26fda6560de4ffb0cd4451c7482a9b6e)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/src/multimedia/alsa/qalsaaudiosink.cpp b/src/multimedia/alsa/qalsaaudiosink.cpp
index 2417d6051..98a68861f 100644
--- a/src/multimedia/alsa/qalsaaudiosink.cpp
+++ b/src/multimedia/alsa/qalsaaudiosink.cpp
@@ -157,6 +157,11 @@ void QAlsaAudioSink::start(QIODevice* device)
     pullMode = true;
     audioSource = device;
 
+    connect(audioSource, &QIODevice::readyRead, timer, [this] {
+        if (!timer->isActive()) {
+            timer->start(period_time / 1000);
+        }
+    });
     deviceState = QAudio::ActiveState;
 
     open();
@@ -606,11 +611,13 @@ bool QAlsaAudioSink::deviceReady()
 
         } else if(l == 0) {
             // Did not get any data to output
+            timer->stop();
+            snd_pcm_drain(handle);
             bytesAvailable = bytesFree();
             if(bytesAvailable > snd_pcm_frames_to_bytes(handle, buffer_frames-period_frames)) {
                 // Underrun
                 if (deviceState != QAudio::IdleState) {
-                    errorState = QAudio::UnderrunError;
+                    errorState = audioSource->atEnd() ? QAudio::NoError : QAudio::UnderrunError;
                     emit errorChanged(errorState);
                     deviceState = QAudio::IdleState;
                     emit stateChanged(deviceState);