1 files changed, 41 insertions, 12 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 706d249a9ad6..26268ffb8274 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -690,7 +690,7 @@ static bool get_alias_id(struct usb_device *dev, unsigned int *id)
 	return false;
 }
 
-static bool check_delayed_register_option(struct snd_usb_audio *chip, int iface)
+static int check_delayed_register_option(struct snd_usb_audio *chip)
 {
 	int i;
 	unsigned int id, inum;
@@ -699,14 +699,31 @@ static bool check_delayed_register_option(struct snd_usb_audio *chip, int iface)
 		if (delayed_register[i] &&
 		    sscanf(delayed_register[i], "%x:%x", &id, &inum) == 2 &&
 		    id == chip->usb_id)
-			return iface < inum;
+			return inum;
 	}
 
-	return false;
+	return -1;
 }
 
 static const struct usb_device_id usb_audio_ids[]; /* defined below */
 
+/* look for the last interface that matches with our ids and remember it */
+static void find_last_interface(struct snd_usb_audio *chip)
+{
+	struct usb_host_config *config = chip->dev->actconfig;
+	struct usb_interface *intf;
+	int i;
+
+	if (!config)
+		return;
+	for (i = 0; i < config->desc.bNumInterfaces; i++) {
+		intf = config->interface[i];
+		if (usb_match_id(intf, usb_audio_ids))
+			chip->last_iface = intf->altsetting[0].desc.bInterfaceNumber;
+	}
+	usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface);
+}
+
 /* look for the corresponding quirk */
 static const struct snd_usb_audio_quirk *
 get_alias_quirk(struct usb_device *dev, unsigned int id)
@@ -725,6 +742,18 @@ get_alias_quirk(struct usb_device *dev, unsigned int id)
 	return NULL;
 }
 
+/* register card if we reach to the last interface or to the specified
+ * one given via option
+ */
+static int try_to_register_card(struct snd_usb_audio *chip, int ifnum)
+{
+	if (check_delayed_register_option(chip) == ifnum ||
+	    chip->last_iface == ifnum ||
+	    usb_interface_claimed(usb_ifnum_to_if(chip->dev, chip->last_iface)))
+		return snd_card_register(chip->card);
+	return 0;
+}
+
 /*
  * probe the active usb device
  *
@@ -813,6 +842,7 @@ static int usb_audio_probe(struct usb_interface *intf,
 			err = -ENODEV;
 			goto __error;
 		}
+		find_last_interface(chip);
 	}
 
 	if (chip->num_interfaces >= MAX_CARD_INTERFACES) {
@@ -862,15 +892,9 @@ static int usb_audio_probe(struct usb_interface *intf,
 		chip->need_delayed_register = false; /* clear again */
 	}
 
-	/* we are allowed to call snd_card_register() many times, but first
-	 * check to see if a device needs to skip it or do anything special
-	 */
-	if (!snd_usb_registration_quirk(chip, ifnum) &&
-	    !check_delayed_register_option(chip, ifnum)) {
-		err = snd_card_register(chip->card);
-		if (err < 0)
-			goto __error;
-	}
+	err = try_to_register_card(chip, ifnum);
+	if (err < 0)
+		goto __error_no_register;
 
 	if (chip->quirk_flags & QUIRK_FLAG_SHARE_MEDIA_DEVICE) {
 		/* don't want to fail when snd_media_device_create() fails */
@@ -889,6 +913,11 @@ static int usb_audio_probe(struct usb_interface *intf,
 	return 0;
 
  __error:
+	/* in the case of error in secondary interface, still try to register */
+	if (chip)
+		try_to_register_card(chip, ifnum);
+
+ __error_no_register:
 	if (chip) {
 		/* chip->active is inside the chip->card object,
 		 * decrement before memory is possibly returned.