ALSA: usb-audio: Show sync endpoint information in proc outputs

Now the sync endpoints have been parsed at the beginning and won't be
changed dynamically, let's show them in the proc outputs for helping
debugging.
Tested-by: NKeith Milner <kamilner@superlative.org>
Tested-by: NDylan Robinson <dylan_robinson@motu.com>
Link: https://lore.kernel.org/r/20201123085347.19667-36-tiwai@suse.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>

sound/usb/proc.c

@@ -108,7 +108,8 @@ static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct s
 					    snd_pcm_format_name(fmt));
 		snd_iprintf(buffer, "\n");
 		snd_iprintf(buffer, "    Channels: %d\n", fp->channels);
-		snd_iprintf(buffer, "    Endpoint: %d %s (%s)\n",
+		snd_iprintf(buffer, "    Endpoint: 0x%02x (%d %s) (%s)\n",
+			    fp->endpoint,
 			    fp->endpoint & USB_ENDPOINT_NUMBER_MASK,
 			    fp->endpoint & USB_DIR_IN ? "IN" : "OUT",
 			    sync_types[(fp->ep_attr & USB_ENDPOINT_SYNCTYPE) >> 2]);
@@ -150,6 +151,19 @@ static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct s
 			snd_iprintf(buffer, "\n");
 		}
 
+		if (fp->sync_ep) {
+			snd_iprintf(buffer, "    Sync Endpoint: 0x%02x (%d %s)\n",
+				    fp->sync_ep,
+				    fp->sync_ep & USB_ENDPOINT_NUMBER_MASK,
+				    fp->sync_ep & USB_DIR_IN ? "IN" : "OUT");
+			snd_iprintf(buffer, "    Sync EP Interface: %d\n",
+				    fp->sync_iface);
+			snd_iprintf(buffer, "    Sync EP Altset: %d\n",
+				    fp->sync_altsetting);
+			snd_iprintf(buffer, "    Implicit Feedback Mode: %s\n",
+				    fp->implicit_fb ? "Yes" : "No");
+		}
+
 		// snd_iprintf(buffer, "    Max Packet Size = %d\n", fp->maxpacksize);
 		// snd_iprintf(buffer, "    EP Attribute = %#x\n", fp->attributes);
 	}