3 files changed, 31 insertions, 5 deletions
diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index e71fe55..0e2ed3d 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/quirks-table.h b/sound/usb/quirks-table.h
index 78e845e..64d25a7 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 acc12f0..2c97185 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,