ALSA: usb-audio: Handle error for the current selector gracefully

Currently we bail out when the device returns an error or an invalid
value for the current clock selector value via
uac_clock_selector_get_val().  But it's possible that the device is
really uninitialized and waits for the setup of the proper route at
first.

For handling such a case, this patch lets the driver dealing with the
error or the invalid error more gracefully, choosing the clock source
automatically instead.

Link: https://lore.kernel.org/r/20210518152112.8016-3-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/clock.c

@@ -299,8 +299,11 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 		/* the entity ID we are looking for is a selector.
 		 * find out what it currently selects */
 		ret = uac_clock_selector_get_val(chip, clock_id);
-		if (ret < 0)
-			return ret;
+		if (ret < 0) {
+			if (!chip->autoclock)
+				return ret;
+			goto find_others;
+		}
 
 		/* Selector values are one-based */
 
@@ -309,7 +312,10 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 				"%s(): selector reported illegal value, id %d, ret %d\n",
 				__func__, clock_id, ret);
 
-			return -EINVAL;
+			if (!chip->autoclock)
+				return -EINVAL;
+			ret = 0;
+			goto find_others;
 		}
 
 	find_source:
@@ -326,6 +332,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;
 
+	find_others:
 		/* The current clock source is invalid, try others. */
 		for (i = 1; i <= pins; i++) {
 			if (i == cur)