1 files changed, 23 insertions, 12 deletions

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index f104c68fe1e0..2c971858d6b7 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -306,7 +306,6 @@ int snd_usb_create_quirk(struct snd_usb_audio *chip,
                 [QUIRK_MIDI_YAMAHA] = create_any_midi_quirk,
                 [QUIRK_MIDI_MIDIMAN] = create_any_midi_quirk,
                 [QUIRK_MIDI_NOVATION] = create_any_midi_quirk,
-                [QUIRK_MIDI_MBOX2] = create_any_midi_quirk,
                 [QUIRK_MIDI_RAW_BYTES] = create_any_midi_quirk,
                 [QUIRK_MIDI_EMAGIC] = create_any_midi_quirk,
                 [QUIRK_MIDI_CME] = create_any_midi_quirk,
@@ -388,11 +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");
 
@@ -528,11 +529,11 @@ static void mbox2_setup_48_24_magic(struct usb_device *dev)
 #define MBOX2_BOOT_LOADING     0x01 /* Hard coded into the device */
 #define MBOX2_BOOT_READY       0x02 /* Hard coded into the device */
 
-int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
+static int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
 {
         struct usb_host_config *config = dev->actconfig;
         int err;
-        u8 bootresponse;
+        u8 bootresponse[12];
         int fwsize;
         int count;
 
@@ -546,20 +547,20 @@ int snd_usb_mbox2_boot_quirk(struct usb_device *dev)
         snd_printd("usb-audio: Sending Digidesign Mbox 2 boot sequence...\n");
 
         count = 0;
-        bootresponse = MBOX2_BOOT_LOADING;
-        while ((bootresponse == MBOX2_BOOT_LOADING) && (count < 10)) {
+        bootresponse[0] = MBOX2_BOOT_LOADING;
+        while ((bootresponse[0] == MBOX2_BOOT_LOADING) && (count < 10)) {
                 msleep(500); /* 0.5 second delay */
                 snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0),
                         /* Control magic - load onboard firmware */
                         0x85, 0xc0, 0x0001, 0x0000, &bootresponse, 0x0012);
-                if (bootresponse == MBOX2_BOOT_READY)
+                if (bootresponse[0] == MBOX2_BOOT_READY)
                         break;
                 snd_printd("usb-audio: device not ready, resending boot sequence...\n");
                 count++;
         }
 
-        if (bootresponse != MBOX2_BOOT_READY) {
-                snd_printk(KERN_ERR "usb-audio: Unknown bootresponse=%d, or timed out, ignoring device.\n", bootresponse);
+        if (bootresponse[0] != MBOX2_BOOT_READY) {
+                snd_printk(KERN_ERR "usb-audio: Unknown bootresponse=%d, or timed out, ignoring device.\n", bootresponse[0]);
                 return -ENODEV;
         }
 
@@ -660,7 +661,6 @@ static int audiophile_skip_setting_quirk(struct snd_usb_audio *chip,
         return 0; /* keep this altsetting */
 }
 
-
 static int fasttrackpro_skip_setting_quirk(struct snd_usb_audio *chip,
                                            int iface, int altno)
 {
@@ -861,6 +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,