ALSA: aloop: Mark paused device as inactive

BugLink: http://bugs.launchpad.net/bugs/1774173

commit 306a4f3c upstream.

Show paused ALSA aloop device as inactive, i.e. the control
"PCM Slave Active" set as false. Notification sent upon state change.

This makes it possible for client capturing from aloop device to know if
data is expected. Without it the client expects data even if playback
is paused.
Signed-off-by: Robert Rosengren <robert.rosengren@axis.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

sound/drivers/aloop.c

@@ -296,6 +296,8 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
 		cable->pause |= stream;
 		loopback_timer_stop(dpcm);
 		spin_unlock(&cable->lock);
+		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+			loopback_active_notify(dpcm);
 		break;
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 	case SNDRV_PCM_TRIGGER_RESUME:
@@ -304,6 +306,8 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
 		cable->pause &= ~stream;
 		loopback_timer_start(dpcm);
 		spin_unlock(&cable->lock);
+		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+			loopback_active_notify(dpcm);
 		break;
 	default:
 		return -EINVAL;
@@ -893,9 +897,11 @@ static int loopback_active_get(struct snd_kcontrol *kcontrol,
 			[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
 	unsigned int val = 0;
 
-	if (cable != NULL)
-		val = (cable->running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
-									1 : 0;
+	if (cable != NULL) {
+		unsigned int running = cable->running ^ cable->pause;
+
+		val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
+	}
 	ucontrol->value.integer.value[0] = val;
 	return 0;
 }