1 files changed, 42 insertions, 3 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 93b6e32cfea..15b151ed489 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -202,13 +202,11 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
 		       struct usb_host_interface *alts,
 		       struct audioformat *fmt)
 {
-	struct usb_interface_descriptor *altsd = get_iface_desc(alts);
-
 	/* if endpoint doesn't have pitch control, bail out */
 	if (!(fmt->attributes & UAC_EP_CS_ATTR_PITCH_CONTROL))
 		return 0;
 
-	switch (altsd->bInterfaceProtocol) {
+	switch (fmt->protocol) {
 	case UAC_VERSION_1:
 	default:
 		return init_pitch_v1(chip, iface, alts, fmt);
@@ -300,6 +298,35 @@ static int deactivate_endpoints(struct snd_usb_substream *subs)
 	return 0;
 }
 
+static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
+				     unsigned int altsetting,
+				     struct usb_host_interface **alts,
+				     unsigned int *ep)
+{
+	struct usb_interface *iface;
+	struct usb_interface_descriptor *altsd;
+	struct usb_endpoint_descriptor *epd;
+
+	iface = usb_ifnum_to_if(dev, ifnum);
+	if (!iface || iface->num_altsetting < altsetting + 1)
+		return -ENOENT;
+	*alts = &iface->altsetting[altsetting];
+	altsd = get_iface_desc(*alts);
+	if (altsd->bAlternateSetting != altsetting ||
+	    altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC ||
+	    (altsd->bInterfaceSubClass != 2 &&
+	     altsd->bInterfaceProtocol != 2   ) ||
+	    altsd->bNumEndpoints < 1)
+		return -ENOENT;
+	epd = get_endpoint(*alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
+					USB_ENDPOINT_USAGE_IMPLICIT_FB)
+		return -ENOENT;
+	*ep = epd->bEndpointAddress;
+	return 0;
+}
+
 /*
  * find a matching format and set up the interface
  */
@@ -395,6 +422,18 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
 			goto add_sync_ep;
 		}
 	}
+	if (is_playback &&
+	    attr == USB_ENDPOINT_SYNC_ASYNC &&
+	    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
+	    altsd->bInterfaceProtocol == 2 &&
+	    altsd->bNumEndpoints == 1 &&
+	    USB_ID_VENDOR(subs->stream->chip->usb_id) == 0x0582 /* Roland */ &&
+	    search_roland_implicit_fb(dev, altsd->bInterfaceNumber + 1,
+				      altsd->bAlternateSetting,
+				      &alts, &ep) >= 0) {
+		implicit_fb = 1;
+		goto add_sync_ep;
+	}
 
 	if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
 	     (!is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&