Both Behringer UMC 202 HD and 404 HD need explicit quirks to enable the implicit feedback mode and start the playback stream primarily. The former seems fixing the stuttering and the latter is required for a playback-only case.

Note that the "clock source 41 is not valid" error message still appears even after this fix, but it should be only once at probe. The reason of the error is still unknown, but this seems to be mostly harmless as it's a one-off error and the driver retires the clock setup and it succeeds afterwards.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215934 Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/quirks.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c index e8468f9b007d..12ce69b04f63 100644 --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -1842,6 +1842,10 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = { QUIRK_FLAG_SHARE_MEDIA_DEVICE | QUIRK_FLAG_ALIGN_TRANSFER), DEVICE_FLG(0x1395, 0x740a, /* Sennheiser DECT */ QUIRK_FLAG_GET_SAMPLE_RATE), + DEVICE_FLG(0x1397, 0x0508, /* Behringer UMC204HD */ + QUIRK_FLAG_PLAYBACK_FIRST | QUIRK_FLAG_GENERIC_IMPLICIT_FB), + DEVICE_FLG(0x1397, 0x0509, /* Behringer UMC404HD */ + QUIRK_FLAG_PLAYBACK_FIRST | QUIRK_FLAG_GENERIC_IMPLICIT_FB), DEVICE_FLG(0x13e5, 0x0001, /* Serato Phono */ QUIRK_FLAG_IGNORE_CTL_ERROR), DEVICE_FLG(0x154e, 0x1002, /* Denon DCD-1500RE */