ALSA: usb-mixer: Add support for Audio Class v2.0

USB Audio Class v2.0 compliant devices have different descriptors and a
different way of setting/getting min/max/res/cur properties. This patch
adds support for them.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 63101ae201cc..130123854a6c 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -10,6 +10,9 @@ struct usb_mixer_interface {
         /* array[MAX_ID_ELEMS], indexed by unit id */
         struct usb_mixer_elem_info **id_elems;
 
+        /* the usb audio specification version this interface complies to */
+        int protocol;
+
         /* Sound Blaster remote control stuff */
         const struct rc_config *rc_cfg;
         u32 rc_code;