From c249177944b650816069f6c49b769baaa94339dc Mon Sep 17 00:00:00 2001
From: Alexander Tsoy <alexander@tsoy.me>
Date: Wed, 15 Jan 2020 18:13:58 +0300
Subject: [PATCH] ALSA: usb-audio: add implicit fb quirk for MOTU M Series
Git-commit: c249177944b650816069f6c49b769baaa94339dc
Patch-mainline: v5.6-rc1
References: bsc#1111666

This fixes crackling sound during playback.

Further note: MOTU is known for reusing Product IDs for different
devices or different generations of the device (e.g. MicroBook
I/II/IIc shares a single Product ID). This patch was only tested with
M4 audio interface, but the same Product ID is also used by M2. Hope
it will work for M2 as well.

Signed-off-by: Alexander Tsoy <alexander@tsoy.me>
Link: https://lore.kernel.org/r/20200115151358.56672-1-alexander@tsoy.me
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/usb/pcm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 2f6a80ca36fc..5844a0c9d0db 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -361,6 +361,10 @@ static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
 		ep = 0x84;
 		ifnum = 0;
 		goto add_sync_ep_from_ifnum;
+	case USB_ID(0x07fd, 0x0008): /* MOTU M Series */
+		ep = 0x81;
+		ifnum = 2;
+		goto add_sync_ep_from_ifnum;
 	case USB_ID(0x0582, 0x01d8): /* BOSS Katana */
 		/* BOSS Katana amplifiers do not need quirks */
 		return 0;
-- 
2.16.4