1 files changed, 58 insertions, 0 deletions
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 0d8aba5f..ec214f8e 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -524,6 +524,64 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 	return 0;
 }
 
+int snd_usb_enable_audio_stream(struct snd_usb_substream *subs,
+	bool enable)
+{
+	struct audioformat *fmt;
+	struct usb_host_interface *alts;
+	struct usb_interface *iface;
+	int ret;
+
+	if (!enable) {
+		if (subs->interface >= 0) {
+			usb_set_interface(subs->dev, subs->interface, 0);
+			subs->altset_idx = 0;
+			subs->interface = -1;
+			subs->cur_audiofmt = NULL;
+		}
+
+		snd_usb_autosuspend(subs->stream->chip);
+		return 0;
+	}
+
+	snd_usb_autoresume(subs->stream->chip);
+	fmt = find_format(subs);
+	if (!fmt) {
+		dev_err(&subs->dev->dev,
+		"cannot set format: format = %#x, rate = %d, channels = %d\n",
+			   subs->pcm_format, subs->cur_rate, subs->channels);
+		return -EINVAL;
+	}
+
+	subs->altset_idx = 0;
+	subs->interface = -1;
+	if (subs->stream->chip->shutdown) {
+		ret = -ENODEV;
+	} else {
+		ret = set_format(subs, fmt);
+		if (ret < 0)
+			return ret;
+
+		iface = usb_ifnum_to_if(subs->dev, subs->cur_audiofmt->iface);
+		alts = &iface->altsetting[subs->cur_audiofmt->altset_idx];
+		ret = snd_usb_init_sample_rate(subs->stream->chip,
+					       subs->cur_audiofmt->iface,
+					       alts,
+					       subs->cur_audiofmt,
+					       subs->cur_rate);
+		if (ret < 0) {
+			dev_err(&subs->dev->dev, "failed to set rate %d\n",
+				subs->cur_rate);
+			return ret;
+		}
+	}
+
+	subs->interface = fmt->iface;
+	subs->altset_idx = fmt->altset_idx;
+
+	return 0;
+}
+
 /*
  * Return the score of matching two audioformats.
  * Veto the audioformat if: