Use control messages for audio data to fix scratch hang.

Use vchiq versioning to try to handle mismatches kernel.img/start.elf

sound/arm/bcm2835-ctl.c

@@ -41,7 +41,7 @@
 static int snd_bcm2835_ctl_info(struct snd_kcontrol *kcontrol,
 				struct snd_ctl_elem_info *uinfo)
 {
-	audio_info(" ... IN ");
+	audio_info(" ... IN\n");
 	if (kcontrol->private_value == PCM_PLAYBACK_VOLUME) {
 		uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
 		uinfo->count = 1;
@@ -58,7 +58,7 @@ static int snd_bcm2835_ctl_info(struct snd_kcontrol *kcontrol,
 		uinfo->value.integer.min = 0;
 		uinfo->value.integer.max = AUDIO_DEST_MAX-1;
 	}
-	audio_info(" ... OUT ");
+	audio_info(" ... OUT\n");
 	return 0;
 }
 
@@ -75,13 +75,13 @@ static int toggle_mute(struct bcm2835_chip *chip, int nmute)
 	if(chip->mute == CTRL_VOL_MUTE)
 	{
 		chip->volume = chip->old_volume; /* copy the old volume back */
-		audio_info("Unmuting, old_volume = %d, volume = %d ...", chip->old_volume, chip->volume);
+		audio_info("Unmuting, old_volume = %d, volume = %d ...\n", chip->old_volume, chip->volume);
 	}
 	else /* otherwise we mute */
 	{
 		chip->old_volume = chip->volume;
 		chip->volume = 26214; /* set volume to minimum level AKA mute */
-		audio_info("Muting, old_volume = %d, volume = %d ...", chip->old_volume, chip->volume);
+		audio_info("Muting, old_volume = %d, volume = %d ...\n", chip->old_volume, chip->volume);
 	}
 
 	chip->mute = nmute;
@@ -112,7 +112,7 @@ static int snd_bcm2835_ctl_put(struct snd_kcontrol *kcontrol,
 	int changed = 0;
 
 	if (kcontrol->private_value == PCM_PLAYBACK_VOLUME) {
-		audio_info("Volume change attempted.. volume = %d new_volume = %d", chip->volume, (int)ucontrol->value.integer.value[0]);
+		audio_info("Volume change attempted.. volume = %d new_volume = %d\n", chip->volume, (int)ucontrol->value.integer.value[0]);
 		if (chip->mute == CTRL_VOL_MUTE) {
 			/* changed = toggle_mute(chip, CTRL_VOL_UNMUTE); */
 			return 1; /* should return 0 to signify no change but the mixer takes this as the opposite sign (no idea why) */
@@ -126,7 +126,7 @@ static int snd_bcm2835_ctl_put(struct snd_kcontrol *kcontrol,
 
 	} else if (kcontrol->private_value == PCM_PLAYBACK_MUTE) {
 		/* Now implemented */
-		audio_info(" Mute attempted");
+		audio_info(" Mute attempted\n");
 		changed = toggle_mute(chip, ucontrol->value.integer.value[0]);
 
 	} else if (kcontrol->private_value == PCM_PLAYBACK_DEVICE) {

sound/arm/bcm2835-pcm.c

@@ -281,14 +281,15 @@ static int snd_bcm2835_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 			if (err == 0) {
 				alsa_stream->running = 1;
 				alsa_stream->draining = 1;
+			} else {
+				audio_error(" Failed to START alsa device (%d)\n", err);
 			}
 		}
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 		audio_debug
 		    ("bcm2835_AUDIO_TRIGGER_STOP running=%d draining=%d\n",
-		     runtime->status->state == SNDRV_PCM_STATE_DRAINING,
-		     alsa_stream->running);
+			     alsa_stream->running, runtime->status->state == SNDRV_PCM_STATE_DRAINING);
 		if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
 			audio_info("DRAINING\n");
 			alsa_stream->draining = 1;
@@ -299,7 +300,7 @@ static int snd_bcm2835_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 		if (alsa_stream->running) {
 			err = bcm2835_audio_stop(alsa_stream);
 			if (err != 0)
-				audio_error(" Failed to STOP alsa device\n");
+				audio_error(" Failed to STOP alsa device (%d)\n", err);
 			alsa_stream->running = 0;
 		}
 		break;