[PATCH] ALSA: usb-audio: add Pioneer DJ DDJ-SZ support

[Hanh Kieu <hhkieu@gmail.com>]

The Pioneer DJ DDJ-SZ exposes its audio interface as USB vendor-specific
class (0xFF) rather than USB Audio Class, so it needs a quirks-table
entry like its sibling Pioneer devices (DJM-750, DJM-850, DJM-900NXS2,
DJM-450, DJM-V10) already have.

The device presents 10 channels of S24_3LE audio in both directions,
fixed at 44.1kHz, on interface 0 altsetting 1: playback on endpoint
0x01, capture on endpoint 0x82. The unit contains its own analog mixer,
and each playback channel pair feeds one of its physical channel strips:
0/1, 2/3, 4/5 and 6/7 feed strips 1-4 respectively, and 8/9 feed the
booth output. The master output is produced in analog by that mixer and
is not carried over USB at all. On the capture side, channels 8/9 are
the mic input; capture channels 0-7 are not yet mapped to specific
physical inputs.

Implicit feedback needs no quirk flag here: is_pioneer_implicit_fb() in
implicit.c already covers vendor 0x08e4 with a vendor-spec class
interface and two endpoints, and the driver duly reports endpoint 0x82
as the playback sync endpoint.

Activation reuses the existing pioneer_djm_set_format_quirk() used by
the DJM-750/850/900NXS2/450/V10 (SET_INTERFACE to altsetting 1, then a
UAC-shaped SET_CUR sample-rate control transfer) with this device's own
captured wIndex (0x0082). Unlike those devices, the DDJ-SZ additionally
needs a vendor "arm" sequence before its capture path produces real
audio -- without it, capture opens and runs with no USB/ALSA errors
but delivers silence (a hard zero on every channel) rather than any
error, so this is easy to miss. The arm sequence is six vendor control
transfers (bmRequestType=0x40, bRequest=3, varying wValue/wIndex, each
followed by a bmRequestType=0xc0, bRequest=0 status read), replicated
byte-for-byte from a USB capture of the official Windows driver.

All of the above -- endpoint numbers, format, channel mapping, and the
arm sequence bytes -- were determined by capturing and decoding real USB
traffic from the Windows driver (USBPcap + Wireshark) during
enumeration, playback, and mic recording, then verifying the format
hypothesis against actual de-interleaved payload data rather than
packet-size arithmetic alone. Both playback and capture have been
verified working with real audio, not just clean enumeration.

Signed-off-by: Hanh Kieu <hhkieu@gmail.com>
---
 sound/usb/quirks-table.h | 47 +++++++++++++++++++++++++++++++
 sound/usb/quirks.c       | 60 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)

diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index a1a33f11d..2da8cbe3e 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -3731,6 +3731,53 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 		}
 	}
 },
+{
+	/*
+	 * Pioneer DJ DDJ-SZ
+	 * 10 channels playback & 10 channels capture @ 44.1kHz S24LE
+	 */
+	USB_DEVICE_VENDOR_SPEC(0x08e4, 0x0191),
+	QUIRK_DRIVER_INFO {
+		QUIRK_DATA_COMPOSITE {
+			{
+				QUIRK_DATA_AUDIOFORMAT(0) {
+					.formats = SNDRV_PCM_FMTBIT_S24_3LE,
+					.channels = 10,
+					.iface = 0,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.endpoint = 0x01,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC|
+						   USB_ENDPOINT_SYNC_ASYNC,
+					.rates = SNDRV_PCM_RATE_44100,
+					.rate_min = 44100,
+					.rate_max = 44100,
+					.nr_rates = 1,
+					.rate_table = (unsigned int[]) { 44100 }
+				}
+			},
+			{
+				QUIRK_DATA_AUDIOFORMAT(0) {
+					.formats = SNDRV_PCM_FMTBIT_S24_3LE,
+					.channels = 10,
+					.iface = 0,
+					.altsetting = 1,
+					.altset_idx = 1,
+					.endpoint = 0x82,
+					.ep_idx = 1,
+					.ep_attr = USB_ENDPOINT_XFER_ISOC|
+						   USB_ENDPOINT_SYNC_ASYNC,
+					.rates = SNDRV_PCM_RATE_44100,
+					.rate_min = 44100,
+					.rate_max = 44100,
+					.nr_rates = 1,
+					.rate_table = (unsigned int[]) { 44100 }
+				}
+			},
+			QUIRK_COMPOSITE_END
+		}
+	}
+},
 {
 	/*
 	 * Pioneer DJ DJM-750MK2
diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 4936d66f9..f09599c0d 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -1767,6 +1767,62 @@ static void set_format_emu_quirk(struct snd_usb_substream *subs,
 	subs->pkt_offset_adj = (emu_samplerate_id >= EMU_QUIRK_SR_176400HZ) ? 4 : 0;
 }
 
+/*
+ * The DDJ-SZ needs a vendor "arm" sequence before its capture path
+ * produces real audio; without it capture runs with no USB or ALSA error
+ * but delivers a hard zero on every channel. The sequence is replicated
+ * byte-for-byte from a USB capture of the Windows driver: each write is
+ * followed by a status read whose content is a fixed value regardless of
+ * what was written, but the read is replicated too, since it is unclear
+ * whether the device requires it to process the preceding write.
+ *
+ * This runs from snd_usb_set_format_quirk(), i.e. on every format setup
+ * rather than once per device. Re-arming is harmless in practice and
+ * keeps the device armed if it is reset behind our back.
+ */
+static void ddj_sz_arm_quirk(struct usb_device *dev)
+{
+	static const struct {
+		u16 value;
+		u16 index;
+		u8 read_len;
+	} cmds[] = {
+		{ 0x0100, 0x8002, 6 },
+		{ 0x0200, 0x8002, 6 },
+		{ 0x0303, 0x8002, 6 },
+		{ 0x0403, 0x8002, 6 },
+		{ 0x050a, 0x8002, 6 },
+		{ 0x0000, 0x8003, 2 },
+	};
+	u8 buf[6];
+	unsigned int i;
+	int err;
+
+	for (i = 0; i < ARRAY_SIZE(cmds); i++) {
+		err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), 3,
+				      USB_DIR_OUT | USB_TYPE_VENDOR |
+				      USB_RECIP_DEVICE,
+				      cmds[i].value, cmds[i].index, NULL, 0);
+		if (err < 0)
+			goto err_out;
+
+		err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), 0,
+				      USB_DIR_IN | USB_TYPE_VENDOR |
+				      USB_RECIP_DEVICE,
+				      0x0000, cmds[i].index, buf,
+				      cmds[i].read_len);
+		if (err < 0)
+			goto err_out;
+	}
+
+	return;
+
+err_out:
+	dev_warn(&dev->dev,
+		 "DDJ-SZ: arm sequence step %u failed (%d), capture may be silent\n",
+		 i, err);
+}
+
 static int pioneer_djm_set_format_quirk(struct snd_usb_substream *subs,
 					u16 windex)
 {
@@ -1948,6 +2004,10 @@ void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
 	case USB_ID(0x08e4, 0x0163): /* Pioneer DJM-850 */
 		pioneer_djm_set_format_quirk(subs, 0x0086);
 		break;
+	case USB_ID(0x08e4, 0x0191): /* Pioneer DDJ-SZ */
+		ddj_sz_arm_quirk(subs->dev);
+		pioneer_djm_set_format_quirk(subs, 0x0082);
+		break;
 	case USB_ID(0x0dba, 0x5000):
 		mbox3_set_format_quirk(subs, fmt); /* Digidesign Mbox 3 */
 		break;

base-commit: 4c4e4be4edd5dbf5f7f6a3ef4fc0c243f2d01b3c
-- 
2.47.3