[PATCH] ALSA: usb-audio: Add native DSD quirk for HiBy FC4

[Achilles Zhang <bnqzzdf@gmail.com>]

The HiBy FC4 with USB ID 32bb:0004 advertises its native DSD
stream as UAC2 RAW_DATA with a 4-byte, 32-bit subslot. Without a
quirk snd-usb-audio leaves this alternate setting as
SNDRV_PCM_FORMAT_SPECIAL, so userspace cannot select a native DSD
format.

Mark the device with QUIRK_FLAG_DSD_RAW so the existing generic raw
DSD handling exposes the stream as DSD_U32_BE.

Tested on an FC4 at DSD256. With the quirk the playback alternate
setting changes from SPECIAL to DSD_U32_BE and reports DOP=0,
bitrev=0; native DSD256 playback works correctly.

Signed-off-by: Achilles Zhang <bnqzzdf@gmail.com>
---
 sound/usb/quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index c587090..924d930 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2542,6 +2542,8 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_IGNORE_CTL_ERROR),
 	DEVICE_FLG(0x3255, 0x0000, /* Luxman D-10X */
 		   QUIRK_FLAG_ITF_USB_DSD_DAC | QUIRK_FLAG_CTL_MSG_DELAY),
+	DEVICE_FLG(0x32bb, 0x0004, /* HiBy FC4 */
+		   QUIRK_FLAG_DSD_RAW),
 	DEVICE_FLG(0x3302, 0x17c2, /* TTGK Technology USB-C Audio */
 		   QUIRK_FLAG_FORCE_IFACE_RESET | QUIRK_FLAG_IFACE_DELAY),
 	DEVICE_FLG(0x339b, 0x3a07, /* Synaptics HONOR USB-C HEADSET */
-- 
2.53.0