1 files changed, 26 insertions, 11 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 0f107834c100..2d3a04d829b7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -301,7 +301,7 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
         struct usb_interface *iface;
         unsigned int ep, attr;
         int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
-        int err;
+        int err, implicit_fb = 0;
 
         iface = usb_ifnum_to_if(dev, fmt->iface);
         if (WARN_ON(!iface))
@@ -326,25 +326,34 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
          * assume it as adaptive-out or sync-in.
          */
         attr = fmt->ep_attr & USB_ENDPOINT_SYNCTYPE;
-        if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
-             (! is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
-            altsd->bNumEndpoints >= 2) {
-                switch (subs->stream->chip->usb_id) {
-                case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
-                case USB_ID(0x0763, 0x2081):
+
+        switch (subs->stream->chip->usb_id) {
+        case USB_ID(0x0763, 0x2080): /* M-Audio FastTrack Ultra */
+        case USB_ID(0x0763, 0x2081):
+                if (is_playback) {
+                        implicit_fb = 1;
                         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;
                 }
+        }
 
+        if (((is_playback && attr == USB_ENDPOINT_SYNC_ASYNC) ||
+             (!is_playback && attr == USB_ENDPOINT_SYNC_ADAPTIVE)) &&
+            altsd->bNumEndpoints >= 2) {
                 /* check sync-pipe endpoint */
                 /* ... and check descriptor size before accessing bSynchAddress
                    because there is a version of the SB Audigy 2 NX firmware lacking
                    the audio fields in the endpoint descriptors */
                 if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
                     (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
-                     get_endpoint(alts, 1)->bSynchAddress != 0)) {
+                     get_endpoint(alts, 1)->bSynchAddress != 0 &&
+                     !implicit_fb)) {
                         snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
                                    dev->devnum, fmt->iface, fmt->altsetting);
                         return -EINVAL;
@@ -352,16 +361,22 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt)
                 ep = get_endpoint(alts, 1)->bEndpointAddress;
                 if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
                     (( is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
-                     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
+                     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)) ||
+                     ( is_playback && !implicit_fb))) {
                         snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
                                    dev->devnum, fmt->iface, fmt->altsetting);
                         return -EINVAL;
                 }
+
+                implicit_fb = (get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_USAGE_MASK)
+                                == USB_ENDPOINT_USAGE_IMPLICIT_FB;
+
 add_sync_ep:
                 subs->sync_endpoint = snd_usb_add_endpoint(subs->stream->chip,
                                                            alts, ep, !subs->direction,
-                                                           SND_USB_ENDPOINT_TYPE_SYNC);
-
+                                                           implicit_fb ?
+                                                                SND_USB_ENDPOINT_TYPE_DATA :
+                                                                SND_USB_ENDPOINT_TYPE_SYNC);
                 if (!subs->sync_endpoint)
                         return -EINVAL;