MOTU M2 stopped working after upgrade to 5.5

[Michael Gebetsroither]

On 25.04.20 21:29, Michael Gebetsroither wrote:
Hi,

> I suspect c249177944b650816069f6c49b769baaa94339dc to be the reason for this
> "ALSA: usb-audio: add implicit fb quirk for MOTU M Series"

Confirmed, if i revert this commit my Motu M2 interface works again as expected.
With full sound quality (no audio drops or cracks in either in or output).
And with the headset fully working again.

Patch i'm running no ontop 5.5

commit 0224cb66ca86863d527c0c93a2052ca663cb2c29 (HEAD -> master)
Author: Michael Gebetsroither <michael at mgeb.org>
Date:   Sat Apr 25 23:33:10 2020 +0200

    Revert "ALSA: usb-audio: add implicit fb quirk for MOTU M Series"

    This reverts commit c249177944b650816069f6c49b769baaa94339dc.

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index a4e4064f9aee..80a6a53b48e7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -366,10 +366,6 @@ 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;

greets,
gebi