6 files changed, 54 insertions, 11 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index ed4d89c8b52..e90daf8cdaa 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1331,16 +1331,23 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void
 		}
 		channels = (hdr->bLength - 7) / csize - 1;
 		bmaControls = hdr->bmaControls;
+		if (hdr->bLength < 7 + csize) {
+			snd_printk(KERN_ERR "usbaudio: unit %u: "
+				   "invalid UAC_FEATURE_UNIT descriptor\n",
+				   unitid);
+			return -EINVAL;
+		}
 	} else {
 		struct uac2_feature_unit_descriptor *ftr = _ftr;
 		csize = 4;
 		channels = (hdr->bLength - 6) / 4 - 1;
 		bmaControls = ftr->bmaControls;
-	}
-
-	if (hdr->bLength < 7 || !csize || hdr->bLength < 7 + csize) {
-		snd_printk(KERN_ERR "usbaudio: unit %u: invalid UAC_FEATURE_UNIT descriptor\n", unitid);
-		return -EINVAL;
+		if (hdr->bLength < 6 + csize) {
+			snd_printk(KERN_ERR "usbaudio: unit %u: "
+				   "invalid UAC_FEATURE_UNIT descriptor\n",
+				   unitid);
+			return -EINVAL;
+		}
 	}
 
 	/* parse the source unit */
diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index e71fe55cebe..0e2ed3d05c4 100644
--- a/sound/usb/mixer_maps.c
+++ b/sound/usb/mixer_maps.c
@@ -179,6 +179,15 @@ static struct usbmix_name_map audigy2nx_map[] = {
 	{ 0 } /* terminator */
 };
 
+static struct usbmix_selector_map c400_selectors[] = {
+	{
+		.id = 0x80,
+		.count = 2,
+		.names = (const char*[]) {"Internal", "SPDIF"}
+	},
+	{ 0 } /* terminator */
+};
+
 static struct usbmix_selector_map audigy2nx_selectors[] = {
 	{
 		.id = 14, /* Capture Source */
@@ -367,6 +376,10 @@ static struct usbmix_ctl_map usbmix_ctl_maps[] = {
 		.map = hercules_usb51_map,
 	},
 	{
+		.id = USB_ID(0x0763, 0x2030),
+		.selector_map = c400_selectors,
+	},
+	{
 		.id = USB_ID(0x08bb, 0x2702),
 		.map = linex_map,
 		.ignore_ctl_error = 1,
diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 0422b1360af..15520de1df5 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -1206,7 +1206,7 @@ static int snd_c400_create_mixer(struct usb_mixer_interface *mixer)
  * are valid they presents mono controls as L and R channels of
  * stereo. So we provide a good mixer here.
  */
-struct std_mono_table ebox44_table[] = {
+static struct std_mono_table ebox44_table[] = {
 	{
 		.unitid = 4,
 		.control = 1,
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index c6593101c04..d82e378d37c 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -511,6 +511,16 @@ static int configure_sync_endpoint(struct snd_usb_substream *subs)
 	struct snd_usb_substream *sync_subs =
 		&subs->stream->substream[subs->direction ^ 1];
 
+	if (subs->sync_endpoint->type != SND_USB_ENDPOINT_TYPE_DATA ||
+	    !subs->stream)
+		return snd_usb_endpoint_set_params(subs->sync_endpoint,
+						   subs->pcm_format,
+						   subs->channels,
+						   subs->period_bytes,
+						   subs->cur_rate,
+						   subs->cur_audiofmt,
+						   NULL);
+
 	/* Try to find the best matching audioformat. */
 	list_for_each_entry(fp, &sync_subs->fmt_list, list) {
 		int score = match_endpoint_audioformats(fp, subs->cur_audiofmt,
diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 78e845ec65d..64d25a7a4d5 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2289,7 +2289,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.rate_table = (unsigned int[]) {
 							44100, 48000, 88200, 96000
 					},
-					.clock = 0x81,
+					.clock = 0x80,
 				}
 			},
 			/* Capture */
@@ -2315,7 +2315,7 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.rate_table = (unsigned int[]) {
 						44100, 48000, 88200, 96000
 					},
-					.clock = 0x81,
+					.clock = 0x80,
 				}
 			},
 			/* MIDI */
diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index acc12f004c2..2c971858d6b 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -387,11 +387,13 @@ static int snd_usb_fasttrackpro_boot_quirk(struct usb_device *dev)
 		 * rules
 		 */
 		err = usb_driver_set_configuration(dev, 2);
-		if (err < 0) {
+		if (err < 0)
 			snd_printdd("error usb_driver_set_configuration: %d\n",
 				    err);
-			return -ENODEV;
-		}
+		/* Always return an error, so that we stop creating a device
+		   that will just be destroyed and recreated with a new
+		   configuration */
+		return -ENODEV;
 	} else
 		snd_printk(KERN_INFO "usb-audio: Fast Track Pro config OK\n");
 
@@ -859,6 +861,17 @@ void snd_usb_endpoint_start_quirk(struct snd_usb_endpoint *ep)
 	if ((le16_to_cpu(ep->chip->dev->descriptor.idVendor) == 0x23ba) &&
 	    ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
 		ep->skip_packets = 4;
+
+	/*
+	 * M-Audio Fast Track C400 - when packets are not skipped, real world
+	 * latency varies by approx. +/- 50 frames (at 96KHz) each time the
+	 * stream is (re)started. When skipping packets 16 at endpoint start
+	 * up, the real world latency is stable within +/- 1 frame (also
+	 * across power cycles).
+	 */
+	if (ep->chip->usb_id == USB_ID(0x0763, 0x2030) &&
+	    ep->type == SND_USB_ENDPOINT_TYPE_DATA)
+		ep->skip_packets = 16;
 }
 
 void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,