Merge remote-tracking branch 'remotes/fslc/4.9-2.3.x-imx' into toradex_4.9-2.3.x-imx-nextColibri-iMX7_LXDE-Image_2.8b6.184-20190401Colibri-iMX6_LXDE-Image_2.8b6.184-20190401Colibri-iMX6ULL_LXDE-Image_2.8b6.184-20190401Apalis-iMX6_LXDE-Image_2.8b6.184-20190401

1 files changed, 8 insertions, 1 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index e6ac7b9b4648..497bad9f2789 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -313,6 +313,9 @@ static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
 	return 0;
 }
 
+/* Setup an implicit feedback endpoint from a quirk. Returns 0 if no quirk
+ * applies. Returns 1 if a quirk was found.
+ */
 static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 					 struct usb_device *dev,
 					 struct usb_interface_descriptor *altsd,
@@ -391,7 +394,7 @@ add_sync_ep:
 
 	subs->data_endpoint->sync_master = subs->sync_endpoint;
 
-	return 0;
+	return 1;
 }
 
 static int set_sync_endpoint(struct snd_usb_substream *subs,
@@ -430,6 +433,10 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
 	if (err < 0)
 		return err;
 
+	/* endpoint set by quirk */
+	if (err > 0)
+		return 0;
+
 	if (altsd->bNumEndpoints < 2)
 		return 0;