Merge tag 'f2fs-for-3.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk...

[~andy/linux] / sound / usb / quirks.c

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index acc12f004c23f05f12b21aa311f2f49dc77652d5..2c971858d6b70a146e57266bfa0afe7a1bfe80cb 100644 (file)
--- 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,