ALSA: usb-audio: Fix implicit fb endpoint setup by quirk

The commit a60945fd08e4 ("ALSA: usb-audio: move implicit fb quirks to
separate function") introduced an error in the handling of quirks for
implicit feedback endpoints. This commit fixes this.

If a quirk successfully sets up an implicit feedback endpoint, usb-audio
no longer tries to find the implicit fb endpoint itself.

Fixes: a60945fd08e4 ("ALSA: usb-audio: move implicit fb quirks to separate function")
Signed-off-by: Manuel Reinhardt <manuel.rhdt@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 382847154227ef69bb77b477402ed6a3a54f4170..db114f3977e0fb4044e88c028f9dea9bad6382af 100644 (file)
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -314,6 +314,9 @@ 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,
@@ -384,7 +387,7 @@ 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,
@@ -423,6 +426,10 @@ 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;