From: Manuel Reinhardt <manuel.rhdt@gmail.com>
Date: Thu, 31 Jan 2019 14:32:35 +0000 (+0100)
Subject: ALSA: usb-audio: Fix implicit fb endpoint setup by quirk
X-Git-Tag: v3.18.135~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=51700aa4bfed4cb2f724386f98bca13277109f2f;p=thirdparty%2Fkernel%2Fstable.git

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 946f89883ae05..26d6d63c50ebc 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -311,6 +311,9 @@ 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,
@@ -370,7 +373,7 @@ 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,
@@ -395,6 +398,10 @@ 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;