ALSA: usb-audio: Carve out connector value checking into a helper

This is preparation for next patch, no functional change intended.
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20210325165918.22593-1-kai.heng.feng@canonical.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer.c

@@ -1446,13 +1446,11 @@ static int mixer_ctl_master_bool_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-/* get the connectors status and report it as boolean type */
-static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
-				   struct snd_ctl_elem_value *ucontrol)
+static int get_connector_value(struct usb_mixer_elem_info *cval,
+			       char *name, int *val)
 {
-	struct usb_mixer_elem_info *cval = kcontrol->private_data;
 	struct snd_usb_audio *chip = cval->head.mixer->chip;
-	int idx = 0, validx, ret, val;
+	int idx = 0, validx, ret;
 
 	validx = cval->control << 8 | 0;
 
@@ -1467,21 +1465,24 @@ static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
 		ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), UAC2_CS_CUR,
 				      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 				      validx, idx, &uac2_conn, sizeof(uac2_conn));
-		val = !!uac2_conn.bNrChannels;
+		if (val)
+			*val = !!uac2_conn.bNrChannels;
 	} else { /* UAC_VERSION_3 */
 		struct uac3_insertion_ctl_blk uac3_conn;
 
 		ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), UAC2_CS_CUR,
 				      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 				      validx, idx, &uac3_conn, sizeof(uac3_conn));
-		val = !!uac3_conn.bmConInserted;
+		if (val)
+			*val = !!uac3_conn.bmConInserted;
 	}
 
 	snd_usb_unlock_shutdown(chip);
 
 	if (ret < 0) {
-		if (strstr(kcontrol->id.name, "Speaker")) {
-			ucontrol->value.integer.value[0] = 1;
+		if (name && strstr(name, "Speaker")) {
+			if (val)
+				*val = 1;
 			return 0;
 		}
 error:
@@ -1491,6 +1492,21 @@ static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
 		return filter_error(cval, ret);
 	}
 
+	return ret;
+}
+
+/* get the connectors status and report it as boolean type */
+static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_value *ucontrol)
+{
+	struct usb_mixer_elem_info *cval = kcontrol->private_data;
+	int ret, val;
+
+	ret = get_connector_value(cval, kcontrol->id.name, &val);
+
+	if (ret < 0)
+		return ret;
+
 	ucontrol->value.integer.value[0] = val;
 	return 0;
 }