set volume on change

selfdrive/ui/soundd/sound.cc

@@ -36,7 +36,10 @@ void Sound::update() {
   if (sm.updated("microphone")) {
     float volume = util::map_val(sm["microphone"].getMicrophone().getFilteredSoundPressureWeightedDb(), 30.f, 60.f, 0.f, 1.f);
     volume = QAudio::convertVolume(volume, QAudio::LogarithmicVolumeScale, QAudio::LinearVolumeScale);
-    Hardware::set_volume(volume);
+    // set volume on changes
+    if (std::exchange(current_volume, std::nearbyint(volume * 10)) != current_volume) {
+      Hardware::set_volume(volume);
+    }
   }
 
   setAlert(Alert::get(sm, 0));

selfdrive/ui/soundd/sound.h

@@ -30,4 +30,5 @@ protected:
   SubMaster sm;
   Alert current_alert = {};
   QMap<AudibleAlert, QPair<QSoundEffect *, int>> sounds;
+  int current_volume = -1;
 };