ALSA: snd-usb-us122l: Fix MIDI output

The US-122L always reads 9 bytes per urb unless they are set to 0xFD.
Signed-off-by: NKarsten Wiese <fzu@wemgehoertderstaat.de>
Cc: stable@kernel.org
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/usb/midi.c

@@ -850,8 +850,8 @@ static void snd_usbmidi_us122l_output(struct snd_usb_midi_out_endpoint *ep,
 		return;
 	}
 
-	memset(urb->transfer_buffer + count, 0xFD, 9 - count);
-	urb->transfer_buffer_length = count;
+	memset(urb->transfer_buffer + count, 0xFD, ep->max_transfer - count);
+	urb->transfer_buffer_length = ep->max_transfer;
 }
 
 static struct usb_protocol_ops snd_usbmidi_122l_ops = {
@@ -1295,6 +1295,13 @@ static int snd_usbmidi_out_endpoint_create(struct snd_usb_midi* umidi,
 	case USB_ID(0x1a86, 0x752d): /* QinHeng CH345 "USB2.0-MIDI" */
 		ep->max_transfer = 4;
 		break;
+		/*
+		 * Some devices only work with 9 bytes packet size:
+		 */
+	case USB_ID(0x0644, 0x800E): /* Tascam US-122L */
+	case USB_ID(0x0644, 0x800F): /* Tascam US-144 */
+		ep->max_transfer = 9;
+		break;
 	}
 	for (i = 0; i < OUTPUT_URBS; ++i) {
 		buffer = usb_alloc_coherent(umidi->dev,