ALSA: usb-audio: mixer: volume quirk for ESS Technology Asus USB DAC

The Asus USB DAC is a USB type-C audio dongle for connecting to
the headset and headphone. The volume minimum value -23040 which
is 0xa600 in hexadecimal with the resolution value 1 indicates
this should be endianness issue caused by the firmware bug. Add
a volume quirk to fix the volume control problem.

Also fixes this warning:
  Warning! Unlikely big volume range (=23040), cval->res is probably wrong.
  [5] FU [Headset Capture Volume] ch = 1, val = -23040/0/1
  Warning! Unlikely big volume range (=23040), cval->res is probably wrong.
  [7] FU [Headset Playback Volume] ch = 1, val = -23040/0/1

Signed-off-by: Chris Chiu <chiu@endlessm.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200526062613.55401-1-chiu@endlessm.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index a88d7854513b96ff7dc3f44ccaebfeea2b12ee35..15769f266790e359bb9c962ebda8464bb52f334d 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1182,6 +1182,14 @@ static void volume_control_quirks(struct usb_mixer_elem_info *cval,
                        cval->res = 384;
                }
                break;
+       case USB_ID(0x0495, 0x3042): /* ESS Technology Asus USB DAC */
+               if ((strstr(kctl->id.name, "Playback Volume") != NULL) ||
+                       strstr(kctl->id.name, "Capture Volume") != NULL) {
+                       cval->min >>= 8;
+                       cval->max = 0;
+                       cval->res = 1;
+               }
+               break;
        }
 }