Merge branch 'for-linus' into for-next

Back-merge of 4.15-rc development branch for further development of
USB-audio stuff.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 18 insertions, 8 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 61b348383de8..2b4ceda36291 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -204,6 +204,10 @@ static int snd_usb_copy_string_desc(struct mixer_build *state,
 				    int index, char *buf, int maxlen)
 {
 	int len = usb_string(state->chip->dev, index, buf, maxlen - 1);
+
+	if (len < 0)
+		return 0;
+
 	buf[len] = 0;
 	return len;
 }
@@ -2169,19 +2173,25 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid,
 	kctl->private_value = (unsigned long)namelist;
 	kctl->private_free = usb_mixer_selector_elem_free;
 
-	nameid = uac_selector_unit_iSelector(desc);
+	/* check the static mapping table at first */
 	len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));
-	if (len)
-		;
-	else if (nameid)
-		snd_usb_copy_string_desc(state, nameid, kctl->id.name,
-					 sizeof(kctl->id.name));
-	else {
-		len = get_term_name(state, &state->oterm,
+	if (!len) {
+		/* no mapping ? */
+		/* if iSelector is given, use it */
+		nameid = uac_selector_unit_iSelector(desc);
+		if (nameid)
+			len = snd_usb_copy_string_desc(state, nameid,
+						       kctl->id.name,
+						       sizeof(kctl->id.name));
+		/* ... or pick up the terminal name at next */
+		if (!len)
+			len = get_term_name(state, &state->oterm,
 				    kctl->id.name, sizeof(kctl->id.name), 0);
+		/* ... or use the fixed string "USB" as the last resort */
 		if (!len)
 			strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
 
+		/* and add the proper suffix */
 		if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
 			append_ctl_name(kctl, " Clock Source");
 		else if ((state->oterm.type & 0xff00) == 0x0100)