The Behringer FCA1616 (1397:0004) returns silent capture samples unless its
playback endpoint is active.

Use the existing fixed implicit-feedback mechanism to keep playback endpoint
0x01 on interface 1 active during capture.

Tested with 16-channel S32_LE capture at 44.1 and 48 kHz.

Signed-off-by: Kitty Makin <autumnull@posteo.net>
---
 sound/usb/implicit.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/usb/implicit.c b/sound/usb/implicit.c
index 77f06da93..bd4d569a8 100644
--- a/sound/usb/implicit.c
+++ b/sound/usb/implicit.c
@@ -76,6 +76,7 @@ static const struct snd_usb_implicit_fb_match playback_implicit_fb_quirks[] = {
 
 /* Implicit feedback quirk table for capture: only FIXED type */
 static const struct snd_usb_implicit_fb_match capture_implicit_fb_quirks[] = {
+	IMPLICIT_FB_FIXED_DEV(0x1397, 0x0004, 0x01, 1), /* Behringer FCA1616 */
 	{} /* terminator */
 };
 
-- 
2.55.0

On Mon, 14 Sep 2026 02:24:24 +0200,
Kitty Makin wrote:
> 
> The Behringer FCA1616 (1397:0004) returns silent capture samples unless its
> playback endpoint is active.
> 
> Use the existing fixed implicit-feedback mechanism to keep playback endpoint
> 0x01 on interface 1 active during capture.
> 
> Tested with 16-channel S32_LE capture at 44.1 and 48 kHz.
> 
> Signed-off-by: Kitty Makin <autumnull@posteo.net>

It's interesting that this capture implicit quirk is still needed.
Maybe we can work around in a different way, but this addition would
be likely simpler.  Let's see whether any other devices need to follow
this pattern, then we can rethink.

In anyway, applied now.  Thanks.


Takashi