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

commit 2bc16b9f3223d049b57202ee702fcb5b9b507019 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index d8a46d46bcd2ad20070bca986b86d694785b352d..b1a1eb1f65aa34d89b07c7dfb6badbc34c1b3a2e 100644 (file)
--- 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;