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

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.

Fixes: f8c11eb7da4a ("ALSA: usb-audio: Add support for Lenovo ThinkStation P620")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20200810133108.31580-1-kai.heng.feng@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index c369c81..5b43e9e 100644 (file)
--- 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 */
        {}
 };