From abe5affda565d8fedb602a4825c56b2445f843f9 Mon Sep 17 00:00:00 2001
From: Lassi Ylikojola <lassi.ylikojola@gmail.com>
Date: Fri, 9 Feb 2018 16:51:36 +0200
Subject: [PATCH] ALSA: usb-audio: add implicit fb quirk for Behringer UFX1204

commit 5e35dc0338d85ccebacf3f77eca1e5dea73155e8 upstream.

Add quirk to ensure a sync endpoint is properly configured.
This patch is a fix for same symptoms on Behringer UFX1204 as patch
from Albertto Aquirre on Dec 8 2016 for Axe-Fx II.

Signed-off-by: Lassi Ylikojola <lassi.ylikojola@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 sound/usb/pcm.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 0bf61d4a1080..17e611064334 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -343,6 +343,15 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 		ep = 0x81;
 		iface = usb_ifnum_to_if(dev, 2);
 
+		if (!iface || iface->num_altsetting == 0)
+			return -EINVAL;
+
+		alts = &iface->altsetting[1];
+		goto add_sync_ep;
+	case USB_ID(0x1397, 0x0002):
+		ep = 0x81;
+		iface = usb_ifnum_to_if(dev, 1);
+
 		if (!iface || iface->num_altsetting == 0)
 			return -EINVAL;