[PATCH] ALSA: usb-audio: Disable Lenovo P620 Rear line-in volume control

[Kai-Heng Feng]

The USB device (0x17aa:0x1046) that support Lenovo P620 rear panel
line-in claim to support volume control, but it doens't seem to have an
AMP, so when line-in volume lowers below 80, nothing gets recorded
anymore.

Disable the volume control to workaround the issue.

Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 sound/usb/mixer_maps.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index c369c81e74c4..5b43e9e40e49 100644
--- a/sound/usb/mixer_maps.c
+++ b/sound/usb/mixer_maps.c
@@ -371,6 +371,7 @@ static const struct usbmix_name_map asus_rog_map[] = {
 };
 
 static const struct usbmix_name_map lenovo_p620_rear_map[] = {
+	{ 19, NULL, 2 }, /* FU, Volume */
 	{ 19, NULL, 12 }, /* FU, Input Gain Pad */
 	{}
 };
-- 
2.17.1