[PATCH 2/4] ALSA: usb-audio: Propagate errors in scarlett_ctl_enum_put()

["Cássio Gabriel" <cassiogabrielcontato@gmail.com>]

scarlett_ctl_enum_put() ignores the return value from
snd_usb_set_cur_mix_value() and reports success whenever the
requested enum value differs from the current one.

If the SET_CUR request fails, the callback still returns success even
though neither the hardware state nor the cached mixer value changed.

Fixes: 76b188c4b370 ("ALSA: usb-audio: Scarlett mixer interface for 6i6, 18i6, 18i8 and 18i20")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
---
 sound/usb/mixer_scarlett.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/usb/mixer_scarlett.c b/sound/usb/mixer_scarlett.c
index 1bb01e827654..673eb8d8724d 100644
--- a/sound/usb/mixer_scarlett.c
+++ b/sound/usb/mixer_scarlett.c
@@ -680,7 +680,9 @@ static int scarlett_ctl_enum_put(struct snd_kcontrol *kctl,
 	val = ucontrol->value.integer.value[0];
 	val = val + opt->start;
 	if (val != oval) {
-		snd_usb_set_cur_mix_value(elem, 0, 0, val);
+		err = snd_usb_set_cur_mix_value(elem, 0, 0, val);
+		if (err < 0)
+			return err;
 		return 1;
 	}
 	return 0;

-- 
2.53.0