From: Lassi Ylikojola <lassi.ylikojola@xxxxxxxxx> This patch has been added to the 4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 5e35dc0338d85ccebacf3f77eca1e5dea73155e8 ] 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@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- sound/usb/pcm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index a51155197277..3351e2f9656d 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; -- 2.14.1