ALSA: hda/hdmi - Don't report spurious jack state changes

The HDMI jack handling reports the state change always via
snd_jack_report() whenever hdmi_present_sense() is called, even if the
state itself doesn't change from the previous time.  This is mostly
harmless but still a bit confusing to user-space.

This patch reduces such spurious jack state changes and reports only
when the state really changed.  Also, as a minor optimization, avoid
overwriting the pin ELD data when the state is identical.
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_hdmi.c

@@ -1421,7 +1421,7 @@ static void hdmi_pcm_reset_pin(struct hdmi_spec *spec,
 /* update per_pin ELD from the given new ELD;
  * setup info frame and notification accordingly
  */
-static void update_eld(struct hda_codec *codec,
+static bool update_eld(struct hda_codec *codec,
 		       struct hdmi_spec_per_pin *per_pin,
 		       struct hdmi_eld *eld)
 {
@@ -1452,18 +1452,22 @@ static void update_eld(struct hda_codec *codec,
 		snd_hdmi_show_eld(codec, &eld->info);
 
 	eld_changed = (pin_eld->eld_valid != eld->eld_valid);
-	if (eld->eld_valid && pin_eld->eld_valid)
+	eld_changed |= (pin_eld->monitor_present != eld->monitor_present);
+	if (!eld_changed && eld->eld_valid && pin_eld->eld_valid)
 		if (pin_eld->eld_size != eld->eld_size ||
 		    memcmp(pin_eld->eld_buffer, eld->eld_buffer,
 			   eld->eld_size) != 0)
 			eld_changed = true;
 
-	pin_eld->monitor_present = eld->monitor_present;
-	pin_eld->eld_valid = eld->eld_valid;
-	pin_eld->eld_size = eld->eld_size;
-	if (eld->eld_valid)
-		memcpy(pin_eld->eld_buffer, eld->eld_buffer, eld->eld_size);
-	pin_eld->info = eld->info;
+	if (eld_changed) {
+		pin_eld->monitor_present = eld->monitor_present;
+		pin_eld->eld_valid = eld->eld_valid;
+		pin_eld->eld_size = eld->eld_size;
+		if (eld->eld_valid)
+			memcpy(pin_eld->eld_buffer, eld->eld_buffer,
+			       eld->eld_size);
+		pin_eld->info = eld->info;
+	}
 
 	/*
 	 * Re-setup pin and infoframe. This is needed e.g. when
@@ -1481,6 +1485,7 @@ static void update_eld(struct hda_codec *codec,
 			       SNDRV_CTL_EVENT_MASK_VALUE |
 			       SNDRV_CTL_EVENT_MASK_INFO,
 			       &get_hdmi_pcm(spec, pcm_idx)->eld_ctl->id);
+	return eld_changed;
 }
 
 /* update ELD and jack state via HD-audio verbs */
@@ -1582,6 +1587,7 @@ static void sync_eld_via_acomp(struct hda_codec *codec,
 	struct hdmi_spec *spec = codec->spec;
 	struct hdmi_eld *eld = &spec->temp_eld;
 	struct snd_jack *jack = NULL;
+	bool changed;
 	int size;
 
 	mutex_lock(&per_pin->lock);
@@ -1608,15 +1614,13 @@ static void sync_eld_via_acomp(struct hda_codec *codec,
 	 * disconnected event. Jack must be fetched before update_eld()
 	 */
 	jack = pin_idx_to_jack(codec, per_pin);
-	update_eld(codec, per_pin, eld);
+	changed = update_eld(codec, per_pin, eld);
 	if (jack == NULL)
 		jack = pin_idx_to_jack(codec, per_pin);
-	if (jack == NULL)
-		goto unlock;
-	snd_jack_report(jack,
-			(eld->monitor_present && eld->eld_valid) ?
+	if (changed && jack)
+		snd_jack_report(jack,
+				(eld->monitor_present && eld->eld_valid) ?
 				SND_JACK_AVOUT : 0);
- unlock:
 	mutex_unlock(&per_pin->lock);
 }