[PATCH v3 0/1] ALSA: usb: Add support for Reloop Jockey 3 DJ controllers

[PATCH v3 0/1] ALSA: usb: Add support for Reloop Jockey 3 DJ controllers

[Frank van de Pol]

Hi Takashi, Jaroslav, and the ALSA community,

After being away from active ALSA development for some 25 years or so, I am
happy to submit this patch to introduce a dedicated driver supporting the
Jockey 3 series of DJ Controllers made by Reloop (specifically covering the
Master Edition and the Remix variants).

I initially evaluated the feasibility of integrating the required logic to
handle the non-standard proprietary Ploytec framing protocol into the standard
USB-audio driver via quirks. However, doing so would require introducing
numerous hardware-specific exceptions throughout the core layout, adding
significant complexity. A clean, isolated driver subdirectory provides much
better long-term maintainability without cluttering the existing class-compliant
architecture.

Following up on the feedback received from the v1 and v2 submissions of my
driver, I have made several updates to the code to improve locking consistency,
lifecycle safety, and the general readability and maintainability of the code.

Changes v1 -> v2:
 - Migrated URB lifecycle management to use standard usb_anchors.
 - Revised and hardened URB buffer memory allocation constraints.
 - Addressed locking consistency, scoping issues, and static analysis warnings
   raised by Takashi and the Sashiko automated review.
 - Implemented dynamic PCM rate constraints when a stream is active.
 - Implemented full MIDI Running Status support for the control surface.
 - Refactored several large code blocks to improve overall readability.
 - Added clarifications on hardware-specific quirks and codec format.
 - Optimized struct jockey3_chip layout for padding and locality.

Changes v2 -> v3:
 - Removed redundant dependencies and defaults from Kconfig.
 - Fixed an AB-BA deadlock condition highlighted by Sashiko review.
 - Corrected an URB resubmission race condition.
 - Implemented explicit USB endpoint validation during initialization.
 - Added Sample Rate verification and post-reset recovery handling.
 - Abstracted disconnect and stopping status checks out into helper functions.
 - Moved substream registration safely under the chip spinlock.
 - Implemented native suspend/resume power management triggers and callbacks.
 - Refactored jockey3_probe() and jockey3_pcm_trigger() for cleaner state tracking.
 - Further refined the internal MIDI Running Status state parser logic.

I have successfully validated and stress-tested this driver across three
distinct hardware architectures to ensure robustness regarding DMA, timing,
and memory alignment:

 - x86_64 (Standard PC desktop environment)
 - armhf (32-bit on a Raspberry Pi 1B -- functional, though tight at 96 kHz)
 - arm64 (64-bit modern SoC environment on a Raspberry Pi 4)

I look forward to your review and feedback, and I am more than happy to
make further architectural adjustments as required.

Best regards,
Frank

Frank van de Pol (1):
  ALSA: usb: Add support for Reloop Jockey 3 DJ controllers

 MAINTAINERS                       |    7 +
 sound/usb/Kconfig                 |    1 +
 sound/usb/Makefile                |    1 +
 sound/usb/jockey3/Kconfig         |   17 +
 sound/usb/jockey3/Makefile        |    3 +
 sound/usb/jockey3/jockey3.c       | 1188 +++++++++++++++++++++++++++++
 sound/usb/jockey3/ploytec_proto.c |  330 ++++++++
 sound/usb/jockey3/ploytec_proto.h |   66 ++
 8 files changed, 1613 insertions(+)
 create mode 100644 sound/usb/jockey3/Kconfig
 create mode 100644 sound/usb/jockey3/Makefile
 create mode 100644 sound/usb/jockey3/jockey3.c
 create mode 100644 sound/usb/jockey3/ploytec_proto.c
 create mode 100644 sound/usb/jockey3/ploytec_proto.h

-- 
2.47.3

[PATCH v3 1/1] ALSA: usb: Add support for Reloop Jockey 3 DJ controllers

[Frank van de Pol]

Introduce a dedicated repository subdirectory and driver for the Reloop
Jockey 3 Master Edition and Reloop Jockey 3 Remix USB DJ controllers.

Because these devices utilize a non-standard, proprietary Ploytec USB
framing protocol instead of standard USB Audio Class (UAC) mechanisms,
they require specialized handling outside of standard quirks.

This driver provides:
 - 24-bit multi-channel (6x4) audio capture and playback.
 - Support for 44.1, 48, 88.2, and 96 kHz sample rates.
 - ALSA RawMIDI input and output mapping for the integrated control surface.

The custom Ploytec encapsulation and streaming format was successfully
reverse-engineered via USB protocol analysis and is isolated cleanly into
ca local hardware-independent codec abstraction.

Signed-off-by: Frank van de Pol <fvdpol@gmail.com>
---
 MAINTAINERS                       |    7 +
 sound/usb/Kconfig                 |    1 +
 sound/usb/Makefile                |    1 +
 sound/usb/jockey3/Kconfig         |   17 +
 sound/usb/jockey3/Makefile        |    3 +
 sound/usb/jockey3/jockey3.c       | 1188 +++++++++++++++++++++++++++++
 sound/usb/jockey3/ploytec_proto.c |  330 ++++++++
 sound/usb/jockey3/ploytec_proto.h |   66 ++
 8 files changed, 1613 insertions(+)
 create mode 100644 sound/usb/jockey3/Kconfig
 create mode 100644 sound/usb/jockey3/Makefile
 create mode 100644 sound/usb/jockey3/jockey3.c
 create mode 100644 sound/usb/jockey3/ploytec_proto.c
 create mode 100644 sound/usb/jockey3/ploytec_proto.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 42feedf526c3..531fa0bf23f6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22539,6 +22539,13 @@ F:	Documentation/filesystems/relay.rst
 F:	include/linux/relay.h
 F:	kernel/relay.c
 
+RELOOP JOCKEY 3 DJ CONTROLLER DRIVER
+M:	Frank van de Pol <fvdpol@gmail.com>
+L:	linux-sound@vger.kernel.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git
+F:	sound/usb/jockey3/
+
 REGISTER MAP ABSTRACTION
 M:	Mark Brown <broonie@kernel.org>
 L:	linux-kernel@vger.kernel.org
diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index b4588915efa1..d7edfbaf099b 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig
@@ -205,6 +205,7 @@ config SND_USB_AUDIO_QMI
 	  will be called snd-usb-audio-qmi.
 
 source "sound/usb/line6/Kconfig"
+source "sound/usb/jockey3/Kconfig"
 
 endif	# SND_USB
 
diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index e62794a87e73..1f045c00dbc9 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -37,3 +37,4 @@ obj-$(CONFIG_SND_USB_US122L) += snd-usbmidi-lib.o
 
 obj-$(CONFIG_SND) += misc/ usx2y/ caiaq/ 6fire/ hiface/ bcd2000/ qcom/
 obj-$(CONFIG_SND_USB_LINE6)	+= line6/
+obj-$(CONFIG_SND_USB_JOCKEY3) += jockey3/
diff --git a/sound/usb/jockey3/Kconfig b/sound/usb/jockey3/Kconfig
new file mode 100644
index 000000000000..52964ff86a8f
--- /dev/null
+++ b/sound/usb/jockey3/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SND_USB_JOCKEY3
+	tristate "Reloop Jockey 3 support"
+	select SND_PCM
+	select SND_RAWMIDI
+	help
+	  Say Y here to include support for the Reloop Jockey 3 DJ controllers.
+          These devices utilize a non-standard, proprietary Ploytec USB
+          protocol.
+
+	  Supported devices:
+
+            * Reloop Jockey 3 Master Edition
+            * Reloop Jockey 3 Remix
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called snd-reloop-jockey3.
diff --git a/sound/usb/jockey3/Makefile b/sound/usb/jockey3/Makefile
new file mode 100644
index 000000000000..85f9c6dcba14
--- /dev/null
+++ b/sound/usb/jockey3/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_SND_USB_JOCKEY3) += snd-reloop-jockey3.o
+snd-reloop-jockey3-objs := jockey3.o ploytec_proto.o
diff --git a/sound/usb/jockey3/jockey3.c b/sound/usb/jockey3/jockey3.c
new file mode 100644
index 000000000000..4026de56b45a
--- /dev/null
+++ b/sound/usb/jockey3/jockey3.c
@@ -0,0 +1,1188 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   ALSA driver for Reloop Jockey 3 devices
+ *
+ *   Copyright (c) 2026 by Frank van de Pol <fvdpol@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/rawmidi.h>
+#include <sound/pcm.h>
+#include <linux/mutex.h>
+#include <linux/cleanup.h>
+#include "ploytec_proto.h"
+
+#define RELOOP_VENDOR_ID         0x200c
+#define RELOOP_JOCKEY3_ME_PID    0x1009
+#define RELOOP_JOCKEY3_REMIX_PID 0x1037
+
+enum { JOCKEY3_ME, JOCKEY3_REMIX };
+
+#define JOCKEY3_N_URBS 8
+
+/* Chip flags */
+#define JOCKEY3_FLAG_DISCONNECTED 0
+#define JOCKEY3_FLAG_STOPPING     1
+
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
+static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;
+
+#define CARD_NAME "Reloop Jockey 3"
+
+module_param_array(index, int, NULL, 0444);
+MODULE_PARM_DESC(index, "Index value for " CARD_NAME " soundcard.");
+module_param_array(id, charp, NULL, 0444);
+MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
+module_param_array(enable, bool, NULL, 0444);
+MODULE_PARM_DESC(enable, "Enable " CARD_NAME " soundcard.");
+
+struct jockey3_chip {
+	/* Core ALSA and USB handles (Mostly read-only after probe) */
+	struct snd_card *card;
+	struct usb_device *dev;
+	struct usb_interface *intf0;
+	struct usb_interface *intf1;
+	struct snd_pcm *pcm;
+	struct snd_rawmidi *rmidi;
+	unsigned char *xfer_buf;
+	struct mutex rate_mutex; // serializes sample rate changes and active stream tracking
+	unsigned long flags;
+	unsigned int current_rate;
+	int active_streams;
+
+	/* MIDI Path */
+	struct snd_rawmidi_substream *midi_in_substream;
+	struct snd_rawmidi_substream *midi_out_substream;
+	struct urb *midi_in_urb;
+	unsigned char *midi_in_buf;
+	spinlock_t midi_lock; // protects MIDI substreams in completion handlers and rate-limiting
+	unsigned int midi_out_acc;
+	struct ploytec_midi_state midi_state;
+
+	/* Playback Path */
+	struct snd_pcm_substream *playback_substream;
+	struct usb_anchor playback_anchor;
+	struct urb *playback_urbs[JOCKEY3_N_URBS];
+	unsigned char *playback_bufs[JOCKEY3_N_URBS];
+	spinlock_t playback_lock; // protects playback stream state and buffer offsets
+	unsigned int dma_off;
+	unsigned int period_off;
+	bool stream_running;
+
+	/* Capture Path */
+	struct snd_pcm_substream *capture_substream;
+	struct usb_anchor capture_anchor;
+	struct urb *capture_urbs[JOCKEY3_N_URBS];
+	unsigned char *capture_bufs[JOCKEY3_N_URBS];
+	spinlock_t capture_lock; // protects capture stream state and buffer offsets
+	unsigned int capture_dma_off;
+	unsigned int capture_period_off;
+	bool capture_running;
+};
+
+static inline bool jockey3_is_disconnected(const struct jockey3_chip *chip)
+{
+	return test_bit(JOCKEY3_FLAG_DISCONNECTED, &chip->flags);
+}
+
+static inline bool jockey3_is_stopping(const struct jockey3_chip *chip)
+{
+	return test_bit(JOCKEY3_FLAG_STOPPING, &chip->flags);
+}
+
+static bool jockey3_process_out_packet(struct jockey3_chip *chip, u8 *urb_buf)
+{
+	struct snd_pcm_substream *substream = chip->playback_substream;
+	struct snd_pcm_runtime *runtime;
+	unsigned int pcm_buffer_size;
+	unsigned int alsa_frame_size;
+	int f;
+
+	if (unlikely(!substream || !substream->runtime))
+		return false;
+
+	runtime = substream->runtime;
+	if (unlikely(!runtime->dma_area))
+		return false;
+
+	pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);
+	alsa_frame_size = runtime->channels * 3;  // 4 * 3 = 12 bytes
+
+	for (f = 0; f < PLOYTEC_PLAYBACK_FRAMES; f++) {
+		ploytec_encode_s24_3le(urb_buf + f * PLOYTEC_PLAYBACK_FRAME_SIZE,
+				       runtime->dma_area + chip->dma_off);
+		chip->dma_off += alsa_frame_size;
+		if (chip->dma_off >= pcm_buffer_size)
+			chip->dma_off -= pcm_buffer_size;
+		chip->period_off += alsa_frame_size;
+	}
+
+	if (chip->period_off >= runtime->period_size * alsa_frame_size) {
+		chip->period_off %= runtime->period_size * alsa_frame_size;
+		return true;
+	}
+
+	return false;
+}
+
+static bool jockey3_process_in_packet(struct jockey3_chip *chip, const u8 *urb_buf)
+{
+	struct snd_pcm_substream *substream = chip->capture_substream;
+	struct snd_pcm_runtime *runtime;
+	unsigned int pcm_buffer_size;
+	unsigned int alsa_frame_size;
+	int f;
+
+	if (unlikely(!substream || !substream->runtime))
+		return false;
+
+	runtime = substream->runtime;
+	if (unlikely(!runtime->dma_area))
+		return false;
+
+	pcm_buffer_size = snd_pcm_lib_buffer_bytes(substream);
+	alsa_frame_size = runtime->channels * 3; // 6 * 3 = 18 bytes
+
+	for (f = 0; f < PLOYTEC_CAPTURE_FRAMES; f++) {
+		ploytec_decode_s24_3le(runtime->dma_area + chip->capture_dma_off,
+				       urb_buf + f * PLOYTEC_CAPTURE_FRAME_SIZE);
+		chip->capture_dma_off += alsa_frame_size;
+		if (chip->capture_dma_off >= pcm_buffer_size)
+			chip->capture_dma_off -= pcm_buffer_size;
+		chip->capture_period_off += alsa_frame_size;
+	}
+
+	if (chip->capture_period_off >= runtime->period_size * alsa_frame_size) {
+		chip->capture_period_off %= runtime->period_size * alsa_frame_size;
+		return true;
+	}
+
+	return false;
+}
+
+static inline bool jockey3_urb_error_fatal(struct jockey3_chip *chip,
+					   struct urb *urb,
+					   const char *type)
+{
+	if (likely(urb->status == 0))
+		return false;
+
+	if (urb->status == -ENOENT || urb->status == -ECONNRESET || urb->status == -ESHUTDOWN)
+		return true;  /* Silent return, no resubmit */
+
+	/* Fatal error */
+	dev_err(&chip->intf0->dev, "%s URB fatal error: %d\n", type, urb->status);
+	set_bit(JOCKEY3_FLAG_DISCONNECTED, &chip->flags);
+	return true;
+}
+
+static void jockey3_capture_callback(struct urb *urb)
+{
+	struct jockey3_chip *chip = urb->context;
+	struct snd_pcm_substream *substream = NULL;
+	bool period_elapsed = false;
+	int ret;
+
+	if (jockey3_urb_error_fatal(chip, urb, "Capture"))
+		return;
+
+	if (unlikely(jockey3_is_disconnected(chip)))
+		return;
+
+	scoped_guard(spinlock_irqsave, &chip->capture_lock) {
+		if (chip->capture_running && chip->capture_substream) {
+			period_elapsed = jockey3_process_in_packet(chip, urb->transfer_buffer);
+			substream = chip->capture_substream;
+		}
+	}
+
+	if (period_elapsed && substream)
+		snd_pcm_period_elapsed(substream);
+
+	if (jockey3_is_stopping(chip))
+		return;
+
+	usb_anchor_urb(urb, &chip->capture_anchor);
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret < 0) {
+		usb_unanchor_urb(urb);
+		if (ret != -ENODEV && ret != -EPERM)
+			dev_err(&chip->intf0->dev, "Failed to resubmit capture URB: %d\n", ret);
+	}
+}
+
+static u8 jockey3_get_next_midi_out_byte(struct jockey3_chip *chip)
+{
+	struct snd_rawmidi_substream *substream;
+	u8 byte;
+	u8 b;
+	unsigned long flags;
+
+	spin_lock_irqsave(&chip->midi_lock, flags);
+
+	/*
+	 * Rate limit MIDI to ~3125 bytes/sec. Sending at higher rates causes buffer
+	 * overflows and message truncation in the device.
+	 */
+	chip->midi_out_acc += 3125;
+	if (chip->midi_out_acc < (chip->current_rate / 10)) {
+		spin_unlock_irqrestore(&chip->midi_lock, flags);
+		return PLOYTEC_MIDI_IDLE_BYTE;
+	}
+	chip->midi_out_acc -= (chip->current_rate / 10);
+
+	/* Handle queued byte from Running Status expansion first before consuming from ALSA */
+	if (chip->midi_state.has_queued_byte) {
+		byte = chip->midi_state.queued_byte;
+		chip->midi_state.has_queued_byte = false;
+		spin_unlock_irqrestore(&chip->midi_lock, flags);
+		dev_dbg(&chip->intf0->dev, "MIDI OUT: 0x%02x\n", byte);
+		return byte;
+	}
+
+	substream = chip->midi_out_substream;
+	spin_unlock_irqrestore(&chip->midi_lock, flags);
+
+	if (!substream)
+		return PLOYTEC_MIDI_IDLE_BYTE;
+
+	if (snd_rawmidi_transmit(substream, &b, 1) != 1)
+		return PLOYTEC_MIDI_IDLE_BYTE;
+
+	spin_lock_irqsave(&chip->midi_lock, flags);
+	byte = ploytec_midi_process_byte(&chip->midi_state, b, &chip->intf0->dev);
+	spin_unlock_irqrestore(&chip->midi_lock, flags);
+	dev_dbg(&chip->intf0->dev, "MIDI OUT: 0x%02x\n", byte);
+
+	return byte;
+}
+
+static void jockey3_playback_callback(struct urb *urb)
+{
+	struct jockey3_chip *chip = urb->context;
+	unsigned char *buf = (unsigned char *)urb->transfer_buffer;
+	struct snd_pcm_substream *substream = NULL;
+	bool period_elapsed = false;
+	int i, ret;
+
+	if (jockey3_urb_error_fatal(chip, urb, "Playback"))
+		return;
+
+	if (unlikely(jockey3_is_disconnected(chip)))
+		return;
+
+	scoped_guard(spinlock_irqsave, &chip->playback_lock) {
+		if (chip->stream_running && chip->playback_substream) {
+			period_elapsed = jockey3_process_out_packet(chip, buf);
+			substream = chip->playback_substream;
+		} else {
+			ploytec_prepare_out_packet(buf);
+		}
+	}
+
+	if (period_elapsed && substream)
+		snd_pcm_period_elapsed(substream);
+
+	buf[PLOYTEC_MIDI_OUT_OFFSET] = jockey3_get_next_midi_out_byte(chip);
+
+	/* Ploytec Sync byte and gap padding */
+	buf[PLOYTEC_SYNC_BYTE_OFFSET] = PLOYTEC_SYNC_BYTE_VALUE;
+	for (i = PLOYTEC_SYNC_BYTE_OFFSET + 1; i < PLOYTEC_PKT_SIZE; i++)
+		buf[i] = 0x00;
+
+	if (jockey3_is_stopping(chip))
+		return;
+
+	usb_anchor_urb(urb, &chip->playback_anchor);
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret < 0) {
+		usb_unanchor_urb(urb);
+		if (ret != -ENODEV && ret != -EPERM)
+			dev_err(&chip->intf0->dev, "Failed to resubmit playback URB: %d\n", ret);
+	}
+}
+
+static void jockey3_midi_in_callback(struct urb *urb)
+{
+	struct jockey3_chip *chip = urb->context;
+	struct snd_rawmidi_substream *substream;
+	unsigned char *buf = (unsigned char *)urb->transfer_buffer;
+	int i, ret;
+
+	if (jockey3_urb_error_fatal(chip, urb, "MIDI IN"))
+		return;
+
+	if (unlikely(jockey3_is_disconnected(chip)))
+		return;
+
+	scoped_guard(spinlock_irqsave, &chip->midi_lock) {
+		substream = chip->midi_in_substream;
+	}
+
+	if (substream) {
+		for (i = 0; i < urb->actual_length; i++) {
+			if (buf[i] != PLOYTEC_MIDI_IDLE_BYTE && buf[i] != 0xF9) {
+				dev_dbg(&chip->intf0->dev, "MIDI IN: 0x%02x\n",
+					buf[i]);
+				snd_rawmidi_receive(substream, &buf[i], 1);
+			}
+		}
+	}
+
+	if (jockey3_is_stopping(chip))
+		return;
+
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret < 0 && ret != -ENODEV && ret != -EPERM)
+		dev_err(&chip->intf0->dev, "Failed to resubmit MIDI IN URB: %d\n", ret);
+}
+
+static void jockey3_stop_urbs(struct jockey3_chip *chip)
+{
+	dev_dbg(&chip->intf0->dev, "Stopping all URBs\n");
+	set_bit(JOCKEY3_FLAG_STOPPING, &chip->flags);
+	usb_kill_urb(chip->midi_in_urb);
+	usb_kill_anchored_urbs(&chip->playback_anchor);
+	usb_kill_anchored_urbs(&chip->capture_anchor);
+}
+
+static void jockey3_start_urbs(struct jockey3_chip *chip)
+{
+	int i, ret;
+
+	if (jockey3_is_disconnected(chip))
+		return;
+
+	dev_dbg(&chip->intf0->dev, "Starting all URBs\n");
+	clear_bit(JOCKEY3_FLAG_STOPPING, &chip->flags);
+	for (i = 0; i < JOCKEY3_N_URBS; i++) {
+		usb_anchor_urb(chip->playback_urbs[i], &chip->playback_anchor);
+		ret = usb_submit_urb(chip->playback_urbs[i], GFP_KERNEL);
+		if (ret < 0) {
+			usb_unanchor_urb(chip->playback_urbs[i]);
+			dev_err(&chip->intf0->dev, "Failed to submit playback URB %d: %d\n",
+				i, ret);
+		}
+
+		usb_anchor_urb(chip->capture_urbs[i], &chip->capture_anchor);
+		ret = usb_submit_urb(chip->capture_urbs[i], GFP_KERNEL);
+		if (ret < 0) {
+			usb_unanchor_urb(chip->capture_urbs[i]);
+			dev_err(&chip->intf0->dev, "Failed to submit capture URB %d: %d\n",
+				i, ret);
+		}
+	}
+	ret = usb_submit_urb(chip->midi_in_urb, GFP_KERNEL);
+	if (ret < 0)
+		dev_err(&chip->intf0->dev, "Failed to submit MIDI IN URB: %d\n", ret);
+}
+
+static int jockey3_set_rate(struct jockey3_chip *chip, unsigned int rate)
+{
+	int ret;
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	dev_dbg(&chip->intf0->dev, "Setting rate to %u Hz\n", rate);
+	ret = ploytec_set_rate(chip->dev, chip->xfer_buf, rate);
+	if (ret < 0) {
+		dev_err(&chip->intf0->dev, "Failed to set rate: %d\n", ret);
+		return ret;
+	}
+	dev_dbg(&chip->intf0->dev, "Rate set OK\n");
+	return 0;
+}
+
+static int jockey3_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	int ret;
+
+	dev_dbg(&chip->intf0->dev, "PCM open stream %d\n", substream->stream);
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	runtime->hw.info =
+		SNDRV_PCM_INFO_MMAP |
+		SNDRV_PCM_INFO_INTERLEAVED |
+		SNDRV_PCM_INFO_BLOCK_TRANSFER |
+		SNDRV_PCM_INFO_MMAP_VALID;
+	runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
+	runtime->hw.rates =
+		SNDRV_PCM_RATE_44100 |
+		SNDRV_PCM_RATE_48000 |
+		SNDRV_PCM_RATE_88200 |
+		SNDRV_PCM_RATE_96000;
+	runtime->hw.rate_min = 44100;
+	runtime->hw.rate_max = 96000;
+	runtime->hw.buffer_bytes_max = 1024 * 1024;
+
+	/*
+	 * The period minimum bytes is limited by packet size of the USB URB frames
+	 * - Playback URB: 10 frames * 4 channels * 3 bytes/sample = 120 bytes
+	 * - Capture URB: 8 frames 6 channels * 3 bytes/sample = 144 bytes
+	 */
+	runtime->hw.period_bytes_min = 144;
+	runtime->hw.period_bytes_max = 512 * 1024;
+	runtime->hw.periods_min = 2;
+	runtime->hw.periods_max = 1024;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		runtime->hw.channels_min = 4;
+		runtime->hw.channels_max = 4;
+	} else {
+		runtime->hw.channels_min = 6;
+		runtime->hw.channels_max = 6;
+	}
+
+	/* Rate constraints under proper locking */
+	scoped_guard(mutex, &chip->rate_mutex) {
+		if (chip->active_streams > 0) {
+			/* Force the new stream to match the existing hardware rate */
+			ret = snd_pcm_hw_constraint_single(runtime,
+							   SNDRV_PCM_HW_PARAM_RATE,
+							   chip->current_rate);
+			if (ret < 0)
+				return ret;
+		}
+
+		chip->active_streams++;
+		dev_dbg(&chip->intf0->dev, "active_streams incremented to %d\n",
+			chip->active_streams);
+	}
+
+	/* Substream registration under spinlock to ensure memory consistency to the ISR*/
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		guard(spinlock_irqsave)(&chip->playback_lock);
+		chip->playback_substream = substream;
+	} else {
+		guard(spinlock_irqsave)(&chip->capture_lock);
+		chip->capture_substream = substream;
+	}
+
+	return 0;
+}
+
+static int jockey3_pcm_close(struct snd_pcm_substream *substream)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+
+	dev_dbg(&chip->intf0->dev, "PCM close stream %d\n", substream->stream);
+
+	guard(mutex)(&chip->rate_mutex);
+	chip->active_streams--;
+	dev_dbg(&chip->intf0->dev, "active_streams decremented to %d\n", chip->active_streams);
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		guard(spinlock_irqsave)(&chip->playback_lock);
+		chip->playback_substream = NULL;
+		chip->stream_running = false;
+	} else {
+		guard(spinlock_irqsave)(&chip->capture_lock);
+		chip->capture_substream = NULL;
+		chip->capture_running = false;
+	}
+	return 0;
+}
+
+static int jockey3_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+
+	dev_dbg(&chip->intf0->dev, "PCM prepare stream %d\n", substream->stream);
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		guard(spinlock_irqsave)(&chip->playback_lock);
+		chip->dma_off = 0;
+		chip->period_off = 0;
+	} else {
+		guard(spinlock_irqsave)(&chip->capture_lock);
+		chip->capture_dma_off = 0;
+		chip->capture_period_off = 0;
+	}
+	return 0;
+}
+
+static int jockey3_pcm_trigger_playback(struct jockey3_chip *chip, int cmd)
+{
+	guard(spinlock_irqsave)(&chip->playback_lock);
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		chip->stream_running = true;
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+		chip->stream_running = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int jockey3_pcm_trigger_capture(struct jockey3_chip *chip, int cmd)
+{
+	guard(spinlock_irqsave)(&chip->capture_lock);
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		chip->capture_running = true;
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+		chip->capture_running = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int jockey3_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+
+	dev_dbg(&chip->intf0->dev, "PCM trigger stream %d, cmd %d\n", substream->stream, cmd);
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		return jockey3_pcm_trigger_playback(chip, cmd);
+	else
+		return jockey3_pcm_trigger_capture(chip, cmd);
+}
+
+static snd_pcm_uframes_t jockey3_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+	unsigned int dma_off;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		scoped_guard(spinlock_irqsave, &chip->playback_lock) {
+			dma_off = chip->dma_off;
+		}
+	} else {
+		scoped_guard(spinlock_irqsave, &chip->capture_lock) {
+			dma_off = chip->capture_dma_off;
+		}
+	}
+	return bytes_to_frames(substream->runtime, dma_off);
+}
+
+static int jockey3_handshake_step(struct jockey3_chip *chip)
+{
+	int ret;
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	ret = ploytec_handshake_step(chip->dev, chip->xfer_buf);
+	if (ret < 0) {
+		dev_err(&chip->intf0->dev, "Ploytec handshake failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int jockey3_pcm_hw_params(struct snd_pcm_substream *substream,
+				 struct snd_pcm_hw_params *hw_params)
+{
+	struct jockey3_chip *chip = snd_pcm_substream_chip(substream);
+	unsigned int rate = params_rate(hw_params);
+	int ret = 0;
+
+	dev_dbg(&chip->intf0->dev, "PCM hw_params rate %u, active_streams %d\n",
+		rate, chip->active_streams);
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+
+	scoped_guard(mutex, &chip->rate_mutex) {
+		if (chip->current_rate == rate) {
+			dev_dbg(&chip->intf0->dev, "Rate already set to %u, skipping change\n",
+				rate);
+			return 0;
+		}
+
+		/*
+		 * If multiple streams are active, the ALSA core should have
+		 * enforced the constraint from jockey3_pcm_open. We still
+		 * sanity check here to be safe.
+		 */
+		if (chip->active_streams > 1) {
+			dev_err(&chip->intf0->dev, "Cannot change rate while other stream is active\n");
+			return -EBUSY;
+		}
+
+		jockey3_stop_urbs(chip);
+		msleep(50);
+
+		ret = jockey3_set_rate(chip, rate);
+		if (ret != 0) {
+			dev_err(&chip->intf0->dev, "Rate change to %u failed: %d\n", rate, ret);
+			jockey3_start_urbs(chip);
+			return ret;
+		}
+		chip->current_rate = rate;
+	}
+
+	dev_dbg(&chip->intf0->dev, "Rate changed to %u successfully, resetting device\n",
+		rate);
+	/*
+	 * Ploytec firmware re-synchronization:
+	 * Ploytec firmware require a full USB reset to re-synchronize the internal
+	 * engine after a sample rate change. Without this, the Capture EP (0x86)
+	 * often stalls or stops transmitting data, leading to EIO errors in ALSA.
+	 *
+	 * TODO: This behavior is currently kept as-is to match observed traces.
+	 * There is an opportunity to improve or replace this once we have a
+	 * better understanding of the Ploytec firmware interaction through
+	 * further protocol analysis or reverse engineering.
+	 *
+	 * pre_reset/post_reset callbacks handle the URB lifecycle.
+	 * We call this outside the rate_mutex to allow pre/post_reset to acquire it.
+	 */
+	usb_reset_device(chip->dev);
+
+	return 0;
+}
+
+static const struct snd_pcm_ops jockey3_pcm_ops = {
+	.open = jockey3_pcm_open,
+	.close = jockey3_pcm_close,
+	.hw_params = jockey3_pcm_hw_params,
+	.prepare = jockey3_pcm_prepare,
+	.trigger = jockey3_pcm_trigger,
+	.pointer = jockey3_pcm_pointer,
+};
+
+static int jockey3_midi_in_open(struct snd_rawmidi_substream *substream)
+{
+	struct jockey3_chip *chip = substream->rmidi->private_data;
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+	return 0;
+}
+
+static int jockey3_midi_in_close(struct snd_rawmidi_substream *substream)
+{
+	return 0;
+}
+
+static void jockey3_midi_in_trigger(struct snd_rawmidi_substream *substream, int up)
+{
+	struct jockey3_chip *chip = substream->rmidi->private_data;
+
+	guard(spinlock_irqsave)(&chip->midi_lock);
+	chip->midi_in_substream = up ? substream : NULL;
+}
+
+static int jockey3_midi_out_open(struct snd_rawmidi_substream *substream)
+{
+	struct jockey3_chip *chip = substream->rmidi->private_data;
+
+	if (jockey3_is_disconnected(chip))
+		return -ENODEV;
+	return 0;
+}
+
+static int jockey3_midi_out_close(struct snd_rawmidi_substream *substream)
+{
+	return 0;
+}
+
+static void jockey3_midi_out_trigger(struct snd_rawmidi_substream *substream, int up)
+{
+	struct jockey3_chip *chip = substream->rmidi->private_data;
+
+	guard(spinlock_irqsave)(&chip->midi_lock);
+	chip->midi_out_substream = up ? substream : NULL;
+}
+
+static const struct snd_rawmidi_ops jockey3_midi_in_ops = {
+	.open = jockey3_midi_in_open,
+	.close = jockey3_midi_in_close,
+	.trigger = jockey3_midi_in_trigger
+};
+
+static const struct snd_rawmidi_ops jockey3_midi_out_ops = {
+	.open = jockey3_midi_out_open,
+	.close = jockey3_midi_out_close,
+	.trigger = jockey3_midi_out_trigger
+};
+
+static int jockey3_handshake(struct jockey3_chip *chip)
+{
+	int ret;
+
+	ret = jockey3_handshake_step(chip);
+	if (ret < 0)
+		return ret;
+
+	chip->current_rate = 44100;
+	ret = jockey3_set_rate(chip, 44100);
+	if (ret < 0)
+		return ret;
+	msleep(20);
+
+	dev_dbg(&chip->intf0->dev, "Handshake complete.\n");
+
+	jockey3_start_urbs(chip);
+
+	return 0;
+}
+
+static const struct usb_device_id jockey3_ids[] = {
+	{ USB_DEVICE(RELOOP_VENDOR_ID, RELOOP_JOCKEY3_ME_PID), .driver_info = JOCKEY3_ME },
+	{ USB_DEVICE(RELOOP_VENDOR_ID, RELOOP_JOCKEY3_REMIX_PID), .driver_info = JOCKEY3_REMIX },
+	{}
+};
+MODULE_DEVICE_TABLE(usb, jockey3_ids);
+
+static struct usb_driver jockey3_driver;
+
+static void jockey3_release_intf1(void *data)
+{
+	struct usb_interface *intf1 = data;
+
+	usb_driver_release_interface(&jockey3_driver, intf1);
+}
+
+static void jockey3_free_urb_action(void *data)
+{
+	usb_free_urb(data);
+}
+
+static void jockey3_kfree_action(void *data)
+{
+	kfree(data);
+}
+
+static void jockey3_stop_urbs_action(void *data)
+{
+	jockey3_stop_urbs(data);
+}
+
+static int jockey3_init_playback_urbs(struct jockey3_chip *chip)
+{
+	struct usb_device *dev = chip->dev;
+	struct usb_interface *intf = chip->intf0;
+	int i, ret;
+
+	for (i = 0; i < JOCKEY3_N_URBS; i++) {
+		chip->playback_bufs[i] = kzalloc(PLOYTEC_PKT_SIZE, GFP_KERNEL);
+		if (!chip->playback_bufs[i])
+			return -ENOMEM;
+		ret = devm_add_action_or_reset(&intf->dev, jockey3_kfree_action,
+					       chip->playback_bufs[i]);
+		if (ret)
+			return ret;
+
+		chip->playback_urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!chip->playback_urbs[i])
+			return -ENOMEM;
+		ret = devm_add_action_or_reset(&intf->dev, jockey3_free_urb_action,
+					       chip->playback_urbs[i]);
+		if (ret)
+			return ret;
+
+		ploytec_prepare_out_packet(chip->playback_bufs[i]);
+
+		usb_fill_bulk_urb(chip->playback_urbs[i], dev,
+				  usb_sndbulkpipe(dev, PLOYTEC_EP_PCM_OUT),
+				  chip->playback_bufs[i], PLOYTEC_PKT_SIZE,
+				  jockey3_playback_callback, chip);
+	}
+
+	return 0;
+}
+
+static int jockey3_init_capture_urbs(struct jockey3_chip *chip)
+{
+	struct usb_device *dev = chip->dev;
+	struct usb_interface *intf = chip->intf0;
+	int i, ret;
+
+	for (i = 0; i < JOCKEY3_N_URBS; i++) {
+		chip->capture_bufs[i] = kzalloc(PLOYTEC_PKT_SIZE, GFP_KERNEL);
+		if (!chip->capture_bufs[i])
+			return -ENOMEM;
+		ret = devm_add_action_or_reset(&intf->dev, jockey3_kfree_action,
+					       chip->capture_bufs[i]);
+		if (ret)
+			return ret;
+
+		chip->capture_urbs[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!chip->capture_urbs[i])
+			return -ENOMEM;
+		ret = devm_add_action_or_reset(&intf->dev, jockey3_free_urb_action,
+					       chip->capture_urbs[i]);
+		if (ret)
+			return ret;
+
+		usb_fill_bulk_urb(chip->capture_urbs[i], dev,
+				  usb_rcvbulkpipe(dev, PLOYTEC_EP_PCM_IN),
+				  chip->capture_bufs[i], PLOYTEC_PKT_SIZE,
+				  jockey3_capture_callback, chip);
+	}
+
+	return 0;
+}
+
+static bool jockey3_has_bulk_endpoint(struct usb_interface *intf, u8 addr, bool out)
+{
+	int i, j;
+
+	for (i = 0; i < intf->num_altsetting; i++) {
+		struct usb_host_interface *alts = &intf->altsetting[i];
+
+		for (j = 0; j < alts->desc.bNumEndpoints; j++) {
+			struct usb_endpoint_descriptor *epd = &alts->endpoint[j].desc;
+
+			if (out) {
+				if (usb_endpoint_is_bulk_out(epd) &&
+				    epd->bEndpointAddress == addr)
+					return true;
+			} else {
+				if (usb_endpoint_is_bulk_in(epd) &&
+				    epd->bEndpointAddress == addr)
+					return true;
+			}
+		}
+	}
+	return false;
+}
+
+static int jockey3_validate_endpoints(struct usb_interface *intf0, struct usb_interface *intf1)
+{
+	if (!jockey3_has_bulk_endpoint(intf0, PLOYTEC_EP_PCM_OUT, true) ||
+	    !jockey3_has_bulk_endpoint(intf0, PLOYTEC_EP_MIDI_IN, false)) {
+		dev_err(&intf0->dev, "Required bulk endpoints not found on Interface 0 (OUT: 0x%02x, IN: 0x%02x)\n",
+			PLOYTEC_EP_PCM_OUT, PLOYTEC_EP_MIDI_IN);
+		return -ENODEV;
+	}
+
+	if (!jockey3_has_bulk_endpoint(intf1, PLOYTEC_EP_PCM_IN, false)) {
+		dev_err(&intf0->dev, "Required bulk IN endpoint not found on Interface 1 (IN: 0x%02x)\n",
+			PLOYTEC_EP_PCM_IN);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static int jockey3_init_pcm(struct jockey3_chip *chip)
+{
+	int ret = snd_pcm_new(chip->card, CARD_NAME " Audio", 0, 1, 1, &chip->pcm);
+
+	if (ret < 0)
+		return ret;
+
+	strscpy(chip->pcm->name, CARD_NAME " Audio", sizeof(chip->pcm->name));
+	chip->pcm->private_data = chip;
+	snd_pcm_set_ops(chip->pcm, SNDRV_PCM_STREAM_PLAYBACK, &jockey3_pcm_ops);
+	snd_pcm_set_ops(chip->pcm, SNDRV_PCM_STREAM_CAPTURE, &jockey3_pcm_ops);
+	snd_pcm_set_managed_buffer_all(chip->pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
+	return 0;
+}
+
+static int jockey3_init_midi(struct jockey3_chip *chip)
+{
+	int ret = snd_rawmidi_new(chip->card, CARD_NAME " MIDI", 0, 1, 1, &chip->rmidi);
+
+	if (ret < 0)
+		return ret;
+
+	chip->rmidi->private_data = chip;
+	strscpy(chip->rmidi->name, CARD_NAME " MIDI", sizeof(chip->rmidi->name));
+	snd_rawmidi_set_ops(chip->rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &jockey3_midi_in_ops);
+	snd_rawmidi_set_ops(chip->rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &jockey3_midi_out_ops);
+	chip->rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT |
+				  SNDRV_RAWMIDI_INFO_OUTPUT |
+				  SNDRV_RAWMIDI_INFO_DUPLEX;
+	return 0;
+}
+
+static void jockey3_setup_card_names(struct jockey3_chip *chip, int driver_info)
+{
+	char *jockey3_type;
+
+	strscpy(chip->card->driver, "snd-reloop-jockey3", sizeof(chip->card->driver));
+	strscpy(chip->card->shortname, CARD_NAME, sizeof(chip->card->shortname));
+
+	switch (driver_info) {
+	case JOCKEY3_ME:
+		jockey3_type = "Master Edition";
+		break;
+	case JOCKEY3_REMIX:
+		jockey3_type = "Remix";
+		break;
+	default:
+		jockey3_type = "Unknown";
+	}
+	snprintf(chip->card->longname, sizeof(chip->card->longname),
+		 "%s %s at USB %s", CARD_NAME, jockey3_type, dev_name(&chip->dev->dev));
+}
+
+static int jockey3_probe(struct usb_interface *intf, const struct usb_device_id *usb_id)
+{
+	struct usb_device *dev = interface_to_usbdev(intf);
+	struct usb_interface *intf1;
+	struct snd_card *card;
+	struct jockey3_chip *chip;
+	int ret;
+	static int dev_idx;
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber != 0)
+		return -ENODEV;
+
+	intf1 = usb_ifnum_to_if(dev, 1);
+	if (!intf1)
+		return -ENODEV;
+
+	ret = jockey3_validate_endpoints(intf, intf1);
+	if (ret < 0)
+		return ret;
+
+	while (dev_idx < SNDRV_CARDS && !enable[dev_idx])
+		dev_idx++;
+
+	if (dev_idx >= SNDRV_CARDS)
+		return -ENODEV;
+
+	ret = snd_devm_card_new(&intf->dev, index[dev_idx], id[dev_idx], THIS_MODULE,
+				sizeof(struct jockey3_chip), &card);
+	if (ret < 0)
+		return ret;
+
+	chip = card->private_data;
+	chip->card = card;
+	chip->dev = dev;
+	chip->intf0 = intf;
+	chip->intf1 = intf1;
+	chip->midi_out_acc = 0;
+	chip->flags = 0;
+	spin_lock_init(&chip->midi_lock);
+	spin_lock_init(&chip->playback_lock);
+	spin_lock_init(&chip->capture_lock);
+	mutex_init(&chip->rate_mutex);
+	memset(&chip->midi_state, 0, sizeof(chip->midi_state));
+
+	init_usb_anchor(&chip->playback_anchor);
+	init_usb_anchor(&chip->capture_anchor);
+
+	chip->xfer_buf = kmalloc(64, GFP_KERNEL);
+	if (!chip->xfer_buf)
+		return -ENOMEM;
+	ret = devm_add_action_or_reset(&intf->dev, jockey3_kfree_action, chip->xfer_buf);
+	if (ret)
+		return ret;
+
+	chip->midi_in_buf = kmalloc(PLOYTEC_PKT_SIZE, GFP_KERNEL);
+	if (!chip->midi_in_buf)
+		return -ENOMEM;
+	ret = devm_add_action_or_reset(&intf->dev, jockey3_kfree_action, chip->midi_in_buf);
+	if (ret)
+		return ret;
+
+	chip->midi_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!chip->midi_in_urb)
+		return -ENOMEM;
+	ret = devm_add_action_or_reset(&intf->dev, jockey3_free_urb_action, chip->midi_in_urb);
+	if (ret)
+		return ret;
+
+	ret = jockey3_init_playback_urbs(chip);
+	if (ret < 0)
+		return ret;
+
+	ret = jockey3_init_capture_urbs(chip);
+	if (ret < 0)
+		return ret;
+
+	usb_fill_bulk_urb(chip->midi_in_urb, dev,
+			  usb_rcvbulkpipe(dev, PLOYTEC_EP_MIDI_IN),
+			  chip->midi_in_buf, PLOYTEC_PKT_SIZE,
+			  jockey3_midi_in_callback, chip);
+
+	/* Stop all URBs on disconnect */
+	ret = devm_add_action(&intf->dev, jockey3_stop_urbs_action, chip);
+	if (ret)
+		return ret;
+
+	ret = jockey3_init_pcm(chip);
+	if (ret < 0)
+		return ret;
+
+	ret = jockey3_init_midi(chip);
+	if (ret < 0)
+		return ret;
+
+	jockey3_setup_card_names(chip, usb_id->driver_info);
+
+	if (card->id[0] == '\0')
+		snd_card_set_id(card, "RJ3");
+
+	ret = usb_driver_claim_interface(&jockey3_driver, intf1, chip);
+	if (ret < 0)
+		return ret;
+	ret = devm_add_action_or_reset(&intf->dev, jockey3_release_intf1, intf1);
+	if (ret)
+		return ret;
+
+	usb_set_intfdata(intf, chip);
+	ret = jockey3_handshake(chip);
+	if (ret < 0)
+		return ret;
+
+	ret = snd_card_register(card);
+	if (ret < 0)
+		return ret;
+
+	dev_idx++;
+	return 0;
+}
+
+static void jockey3_disconnect(struct usb_interface *intf)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+
+	if (chip && intf == chip->intf0) {
+		snd_card_disconnect(chip->card);
+		chip->stream_running = false;
+		chip->capture_running = false;
+		set_bit(JOCKEY3_FLAG_DISCONNECTED, &chip->flags);
+		/*
+		 * Card cleanup, URB stopping/freeing, and interface release
+		 * are all handled automatically by devres.
+		 */
+	}
+	usb_set_intfdata(intf, NULL);
+}
+
+static int jockey3_pre_reset(struct usb_interface *intf)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+
+	if (chip && intf == chip->intf0) {
+		mutex_lock(&chip->rate_mutex);
+		jockey3_stop_urbs(chip);
+	}
+	return 0;
+}
+
+static int jockey3_post_reset(struct usb_interface *intf)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+	u32 hw_rate = 0;
+
+	if (chip && intf == chip->intf0) {
+		jockey3_handshake_step(chip);
+
+		/* Verify if the sample rate persisted through the reset */
+		if (ploytec_get_rate(chip->dev, chip->xfer_buf, &hw_rate) == 0) {
+			if (hw_rate != chip->current_rate) {
+				dev_warn(&chip->intf0->dev,
+					 "Rate mismatch after reset! HW: %u, Expected: %u. Re-applying...\n",
+					 hw_rate, chip->current_rate);
+				jockey3_set_rate(chip, chip->current_rate);
+			} else {
+				dev_dbg(&chip->intf0->dev, "Rate %u Hz persisted through reset\n",
+					hw_rate);
+			}
+		}
+
+		jockey3_start_urbs(chip);
+		mutex_unlock(&chip->rate_mutex);
+	}
+	return 0;
+}
+
+static int jockey3_suspend(struct usb_interface *intf, pm_message_t message)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+
+	if (chip && intf == chip->intf0) {
+		dev_dbg(&intf->dev, "USB suspend, stopping URBs\n");
+		jockey3_stop_urbs(chip);
+	}
+	return 0;
+}
+
+static int jockey3_restore_device(struct jockey3_chip *chip, bool reset)
+{
+	int ret;
+
+	guard(mutex)(&chip->rate_mutex);
+
+	if (reset) {
+		ret = jockey3_handshake_step(chip);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = jockey3_set_rate(chip, chip->current_rate);
+	if (ret < 0)
+		return ret;
+	msleep(20);
+
+	jockey3_start_urbs(chip);
+	return 0;
+}
+
+static int jockey3_resume(struct usb_interface *intf)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+
+	if (chip && intf == chip->intf0) {
+		dev_dbg(&intf->dev, "USB resume, restoring device\n");
+		return jockey3_restore_device(chip, false);
+	}
+	return 0;
+}
+
+static int jockey3_reset_resume(struct usb_interface *intf)
+{
+	struct jockey3_chip *chip = usb_get_intfdata(intf);
+
+	if (chip && intf == chip->intf0) {
+		dev_dbg(&intf->dev, "USB reset resume, restoring device\n");
+		return jockey3_restore_device(chip, true);
+	}
+	return 0;
+}
+
+static struct usb_driver jockey3_driver = {
+	.name = "snd-reloop-jockey3",
+	.probe = jockey3_probe,
+	.disconnect = jockey3_disconnect,
+	.pre_reset = jockey3_pre_reset,
+	.post_reset = jockey3_post_reset,
+	.suspend = jockey3_suspend,
+	.resume = jockey3_resume,
+	.reset_resume = jockey3_reset_resume,
+	.id_table = jockey3_ids
+};
+
+module_usb_driver(jockey3_driver);
+
+MODULE_AUTHOR("Frank van de Pol");
+MODULE_DESCRIPTION(CARD_NAME " ALSA Driver");
+MODULE_LICENSE("GPL");
+MODULE_SOFTDEP("pre: snd-pcm snd-rawmidi");
diff --git a/sound/usb/jockey3/ploytec_proto.c b/sound/usb/jockey3/ploytec_proto.c
new file mode 100644
index 000000000000..4586ddd39c6e
--- /dev/null
+++ b/sound/usb/jockey3/ploytec_proto.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   ALSA driver for Reloop Jockey 3 devices
+ *   Ploytec USB Protocol Handling
+ *
+ *   Copyright (c) 2026 by Frank van de Pol <fvdpol@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include "ploytec_proto.h"
+
+/**
+ * ploytec_encode_s24_3le - Encode 4-channel S24_3LE to 48-byte Ploytec frame
+ * @dest: 48-byte destination buffer
+ * @src: 12-byte source buffer (4 channels * 3 bytes)
+ *
+ * Ploytec Bit-Plane Interleaving (Playback):
+ * The firmware uses a non-standard "bit-plane" format where bits from different
+ * channels are interleaved into the same byte.
+ * - Each 48-byte frame contains 8 samples for 2 pairs of channels.
+ * - Bytes 0-23: ALSA Channels 1 & 3
+ * - Bytes 24-47: ALSA Channels 2 & 4
+ * - Within each 24-byte block, bits are grouped by significance:
+ *   - [0-7]: Most significant bits
+ *   - [8-15]: Middle bits
+ *   - [16-23]: Least significant bits
+ * - bit 0 of each byte corresponds to the first channel in the pair.
+ * - bit 1 of each byte corresponds to the second channel in the pair.
+ */
+void ploytec_encode_s24_3le(u8 *dest, const u8 *src)
+{
+	int i;
+
+	/* First 24 bytes: odd channels (ALSA Ch 1 & 3) */
+	for (i = 0; i < 8; i++) {
+		dest[i] = (((src[2] >> (7 - i)) & 1) << 0) |
+			  (((src[8] >> (7 - i)) & 1) << 1);
+	}
+	for (i = 0; i < 8; i++) {
+		dest[8 + i] = (((src[1] >> (7 - i)) & 1) << 0) |
+			      (((src[7] >> (7 - i)) & 1) << 1);
+	}
+	for (i = 0; i < 8; i++) {
+		dest[16 + i] = (((src[0] >> (7 - i)) & 1) << 0) |
+			       (((src[6] >> (7 - i)) & 1) << 1);
+	}
+
+	/* Second 24 bytes: even channels (ALSA Ch 2 & 4) */
+	for (i = 0; i < 8; i++) {
+		dest[24 + i] = (((src[5] >> (7 - i)) & 1) << 0) |
+			       (((src[11] >> (7 - i)) & 1) << 1);
+	}
+	for (i = 0; i < 8; i++) {
+		dest[24 + 8 + i] = (((src[4] >> (7 - i)) & 1) << 0) |
+				   (((src[10] >> (7 - i)) & 1) << 1);
+	}
+	for (i = 0; i < 8; i++) {
+		dest[24 + 16 + i] = (((src[3] >> (7 - i)) & 1) << 0) |
+				    (((src[9] >> (7 - i)) & 1) << 1);
+	}
+}
+
+/**
+ * ploytec_decode_s24_3le - Decode 64-byte Ploytec frame to 6-channel S24_3LE
+ * @dest: 18-byte destination buffer (6 channels * 3 bytes)
+ * @src: 64-byte source buffer
+ *
+ * Ploytec Bit-Plane Interleaving (Capture):
+ * Similar to encoding, the capture path interleaves 3 pairs of channels
+ * into bit-planes (bit 0, 1, and 2 of each byte).
+ * - Bytes 0x00-0x17: Pair 1 (bits 0,1,2)
+ * - Bytes 0x20-0x37: Pair 2 (bits 0,1,2)
+ */
+void ploytec_decode_s24_3le(u8 *dest, const u8 *src)
+{
+	int i;
+
+	/* Channel 1: odd channel 1 (bit 0 of bytes 0x00-0x17) */
+	dest[0x00] = 0;
+	dest[0x01] = 0;
+	dest[0x02] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x00] |= ((src[0x10 + i] & 0x01) << (7 - i));
+		dest[0x01] |= ((src[0x08 + i] & 0x01) << (7 - i));
+		dest[0x02] |= ((src[0x00 + i] & 0x01) << (7 - i));
+	}
+
+	/* Channel 2: even channel 2 (bit 0 of bytes 0x20-0x37) */
+	dest[0x03] = 0;
+	dest[0x04] = 0;
+	dest[0x05] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x03] |= ((src[0x30 + i] & 0x01) << (7 - i));
+		dest[0x04] |= ((src[0x28 + i] & 0x01) << (7 - i));
+		dest[0x05] |= ((src[0x20 + i] & 0x01) << (7 - i));
+	}
+
+	/* Channel 3: odd channel 3 (bit 1 of bytes 0x00-0x17) */
+	dest[0x06] = 0;
+	dest[0x07] = 0;
+	dest[0x08] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x06] |= (((src[0x10 + i] & 0x02) >> 1) << (7 - i));
+		dest[0x07] |= (((src[0x08 + i] & 0x02) >> 1) << (7 - i));
+		dest[0x08] |= (((src[0x00 + i] & 0x02) >> 1) << (7 - i));
+	}
+
+	/* Channel 4: even channel 4 (bit 1 of bytes 0x20-0x37) */
+	dest[0x09] = 0;
+	dest[0x0A] = 0;
+	dest[0x0B] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x09] |= (((src[0x30 + i] & 0x02) >> 1) << (7 - i));
+		dest[0x0A] |= (((src[0x28 + i] & 0x02) >> 1) << (7 - i));
+		dest[0x0B] |= (((src[0x20 + i] & 0x02) >> 1) << (7 - i));
+	}
+
+	/* Channel 5: odd channel 5 (bit 2 of bytes 0x00-0x17) */
+	dest[0x0C] = 0;
+	dest[0x0D] = 0;
+	dest[0x0E] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x0C] |= (((src[0x10 + i] & 0x04) >> 2) << (7 - i));
+		dest[0x0D] |= (((src[0x08 + i] & 0x04) >> 2) << (7 - i));
+		dest[0x0E] |= (((src[0x00 + i] & 0x04) >> 2) << (7 - i));
+	}
+
+	/* Channel 6: even channel 6 (bit 2 of bytes 0x20-0x37) */
+	dest[0x0F] = 0;
+	dest[0x10] = 0;
+	dest[0x11] = 0;
+	for (i = 0; i < 8; i++) {
+		dest[0x0F] |= (((src[0x30 + i] & 0x04) >> 2) << (7 - i));
+		dest[0x10] |= (((src[0x28 + i] & 0x04) >> 2) << (7 - i));
+		dest[0x11] |= (((src[0x20 + i] & 0x04) >> 2) << (7 - i));
+	}
+}
+
+/**
+ * ploytec_prepare_out_packet - Prepare a playback packet with default sync/MIDI padding
+ * @buf: 512-byte destination buffer
+ *
+ * Sets the initial pattern: MIDI slot (480) is idle (0xFD), sync byte is
+ * set to 0xFF at offset 481, and the padding gap (482-511) is zero-filled.
+ */
+void ploytec_prepare_out_packet(u8 *buf)
+{
+	memset(buf, 0, PLOYTEC_PKT_SIZE);
+	buf[PLOYTEC_MIDI_OUT_OFFSET] = PLOYTEC_MIDI_IDLE_BYTE;
+	buf[PLOYTEC_SYNC_BYTE_OFFSET] = PLOYTEC_SYNC_BYTE_VALUE;
+}
+
+/**
+ * ploytec_handshake_step - Perform Ploytec handshake sequence as observed in captured USB traces.
+ * @dev: USB device
+ * @xfer_buf: Temporary transfer buffer
+ */
+int ploytec_handshake_step(struct usb_device *dev, void *xfer_buf)
+{
+	u8 *buf = xfer_buf;
+	u8 status;
+	int ret;
+
+	ret = usb_set_interface(dev, 0, 1);
+	if (ret < 0)
+		return ret;
+	msleep(20);
+
+	ret = usb_set_interface(dev, 1, 1);
+	if (ret < 0)
+		return ret;
+	msleep(20);
+
+	/*
+	 * Read Firmware (Request 0x56):
+	 * This request often fails on the Reloop Jockey3 devices but appears
+	 * to be a necessary "poke" that advances the internal state machine.
+	 *
+	 * TODO: This behavior is currently kept as-is to match observed traces.
+	 * There is an opportunity to improve or replace this once we have a
+	 * better understanding of the Ploytec firmware interaction through
+	 * further protocol analysis or reverse engineering.
+	 */
+	ret = usb_control_msg_recv(dev, 0, PLOYTEC_REQ_FIRMWARE, 0xC0, 0, 0,
+				   buf, 15, 2000, GFP_KERNEL);
+	msleep(20);
+
+	/* Read Status (Request 0x49) */
+	ret = usb_control_msg_recv(dev, 0, PLOYTEC_REQ_STATUS, 0xC0, 0, 0,
+				   buf, 1, 2000, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	status = buf[0];
+	msleep(20);
+
+	/* Enable device if READY bit is not set */
+	if (!(status & PLOYTEC_STATUS_READY)) {
+		ret = usb_control_msg_send(dev, 0, PLOYTEC_REQ_STATUS, 0x40,
+					   (uint16_t)((status | PLOYTEC_STATUS_READY) & 0xFF),
+					   0, NULL, 0, 2000, GFP_KERNEL);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * ploytec_get_rate - Read hardware sample rate
+ * @dev: USB device
+ * @xfer_buf: Temporary transfer buffer
+ * @rate: Pointer to store the rate
+ */
+int ploytec_get_rate(struct usb_device *dev, void *xfer_buf, u32 *rate)
+{
+	u8 *buf = xfer_buf;
+	int ret;
+
+	/* Read rate from Playback EP 0x05 */
+	ret = usb_control_msg_recv(dev, 0, PLOYTEC_REQ_GET_RATE, 0xA2,
+				   0x0100, 0x0005, buf, 3, 2000, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	*rate = (u32)buf[0] | ((u32)buf[1] << 8) | ((u32)buf[2] << 16);
+	return 0;
+}
+
+/**
+ * ploytec_set_rate - Set hardware sample rate
+ * @dev: USB device
+ * @xfer_buf: Temporary transfer buffer
+ * @rate: Sample rate in Hz
+ */
+int ploytec_set_rate(struct usb_device *dev, void *xfer_buf, u32 rate)
+{
+	u8 *buf = xfer_buf;
+	u32 current_hw_rate = 0;
+	int ret;
+
+	ploytec_get_rate(dev, xfer_buf, &current_hw_rate);
+	pr_debug("ploytec: Setting rate %u Hz (current hw rate: %u Hz)\n",
+		 rate, current_hw_rate);
+
+	buf[0] = rate & 0xFF;
+	buf[1] = (rate >> 8) & 0xFF;
+	buf[2] = (rate >> 16) & 0xFF;
+
+	/* Set rate on Capture EP 0x86 */
+	ret = usb_control_msg_send(dev, 0, PLOYTEC_SET_RATE, PLOYTEC_SET_RATE_VAL,
+				   0x0100, 0x0086, buf, 3, 2000, GFP_KERNEL);
+	if (ret < 0) {
+		pr_err("ploytec: Failed to set rate on EP 0x86: %d\n", ret);
+		return ret;
+	}
+
+	msleep(50);
+
+	/* Set rate on Playback EP 0x05 */
+	ret = usb_control_msg_send(dev, 0, PLOYTEC_SET_RATE, PLOYTEC_SET_RATE_VAL,
+				   0x0100, 0x0005, buf, 3, 2000, GFP_KERNEL);
+	if (ret < 0) {
+		pr_err("ploytec: Failed to set rate on EP 0x05: %d\n", ret);
+		return ret;
+	}
+
+	msleep(50);
+
+	if (ploytec_get_rate(dev, xfer_buf, &current_hw_rate) == 0) {
+		if (current_hw_rate != rate)
+			pr_warn("ploytec: Rate mismatch! Requested %u Hz, Hardware at %u Hz\n",
+				rate, current_hw_rate);
+		else
+			pr_debug("ploytec: Rate verified as %u Hz\n", current_hw_rate);
+	}
+
+	return 0;
+}
+
+/**
+ * ploytec_midi_process_byte - Process a MIDI byte for Ploytec protocol
+ * @state: The MIDI state machine instance
+ * @b: The raw MIDI byte
+ * @dev: Pointer to the struct device for logging
+ *
+ * The Ploytec firmware does not handle MIDI Running Status. To avoid data issues processing
+ * valid MIDI streams with Running Status, we implement a simple state machine to expand the
+ * Running Status messages into full MIDI messages before sending them to the device.
+ */
+u8 ploytec_midi_process_byte(struct ploytec_midi_state *state, u8 b, struct device *dev)
+{
+	u8 byte;
+
+	if (b >= 0x80) { // Status byte
+		if (b < 0xf0) { // Channel Voice Message (0x80-0xEF)
+			state->running_status = b;
+			/* Determine expected data bytes based on MIDI opcode */
+			if ((b & 0xf0) == 0xc0 || (b & 0xf0) == 0xd0)
+				state->expected_data = 1; // PC, Channel Pressure
+			else
+				state->expected_data = 2; // Note On/Off, CC, etc.
+		} else if (b < 0xf8) { // System Common Message (0xf0-0xf7)
+			/* System Common messages clear Running Status */
+			state->running_status = 0;
+			state->expected_data = 0;
+		}
+		/* Real-time messages (0xf8-0xff) do not affect state */
+
+		state->data_count = state->expected_data; // initialise expected data byte count
+		return b;
+	}
+
+	/* Data byte */
+	if (state->data_count > 0) {
+		state->data_count--;
+		return b;
+	} else if (state->running_status >= 0x80) {
+		/* Message is complete but we got a data byte -> expand Running Status */
+		byte = state->running_status;
+		state->queued_byte = b;
+		state->has_queued_byte = true;
+		state->data_count = state->expected_data - 1; // already 1 byte queued
+		return byte;
+	}
+
+	/* No running status expansion active, just send the data byte */
+	return b;
+}
+
diff --git a/sound/usb/jockey3/ploytec_proto.h b/sound/usb/jockey3/ploytec_proto.h
new file mode 100644
index 000000000000..b90628cd5608
--- /dev/null
+++ b/sound/usb/jockey3/ploytec_proto.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   ALSA driver for Reloop Jockey 3 devices
+ *   Ploytec USB Protocol Handling
+ *
+ *   Copyright (c) 2026 by Frank van de Pol <fvdpol@gmail.com>
+ */
+
+#ifndef PLOYTEC_PROTO_H
+#define PLOYTEC_PROTO_H
+
+#include <linux/types.h>
+#include <linux/usb.h>
+
+/* Ploytec Protocol Constants */
+#define PLOYTEC_PKT_SIZE 512
+#define PLOYTEC_MIDI_IDLE_BYTE 0xFD
+
+/* Playback & MIDI Out (EP 0x05) */
+#define PLOYTEC_EP_PCM_OUT 0x05
+#define PLOYTEC_PLAYBACK_FRAMES 10
+#define PLOYTEC_PLAYBACK_FRAME_SIZE 48
+#define PLOYTEC_MIDI_OUT_OFFSET 480
+#define PLOYTEC_SYNC_BYTE_OFFSET 481
+#define PLOYTEC_SYNC_BYTE_VALUE 0xFF
+
+/* Capture (EP 0x86) */
+#define PLOYTEC_EP_PCM_IN 0x86
+#define PLOYTEC_CAPTURE_FRAMES 8
+#define PLOYTEC_CAPTURE_FRAME_SIZE 64
+
+/* MIDI In (EP 0x83) */
+#define PLOYTEC_EP_MIDI_IN 0x83
+
+/* Protocol Commands */
+#define PLOYTEC_REQ_FIRMWARE 0x56
+#define PLOYTEC_REQ_STATUS   0x49
+#define PLOYTEC_REQ_GET_RATE 0x81
+#define PLOYTEC_SET_RATE     0x01
+#define PLOYTEC_SET_RATE_VAL 0x22
+
+/* Status Bits */
+#define PLOYTEC_STATUS_READY 0x20
+
+/* Bit-shuffling codec for S24_3LE (3 bytes per sample) */
+void ploytec_encode_s24_3le(u8 *dest, const u8 *src);
+void ploytec_decode_s24_3le(u8 *dest, const u8 *src);
+
+struct ploytec_midi_state {
+	int expected_data;	// number data bytes for the 'running status' voice message
+	int data_count;
+	u8 running_status;	// the 'running status' (voice message)
+	u8 queued_byte;
+	bool has_queued_byte;
+};
+
+/* MIDI protocol state machine */
+u8 ploytec_midi_process_byte(struct ploytec_midi_state *state, u8 b, struct device *dev);
+
+/* Protocol Helpers */
+void ploytec_prepare_out_packet(u8 *buf);
+int ploytec_handshake_step(struct usb_device *dev, void *xfer_buf);
+int ploytec_get_rate(struct usb_device *dev, void *xfer_buf, u32 *rate);
+int ploytec_set_rate(struct usb_device *dev, void *xfer_buf, u32 rate);
+
+#endif /* PLOYTEC_PROTO_H */
-- 
2.47.3

Re: [PATCH v3 1/1] ALSA: usb: Add support for Reloop Jockey 3 DJ controllers

[Frank van de Pol]

On Sun, Jun 21, 2026 at 09:11:30PM -0400, Frank van de Pol wrote:
> Introduce a dedicated repository subdirectory and driver for the Reloop
> Jockey 3 Master Edition and Reloop Jockey 3 Remix USB DJ controllers.
>

The Sashiko review for the latest version of my patch has quite a few
interesting observations/questions...  which I need to have a closer look
at and likely need to correct.

https://sashiko.dev/#/patchset/20260622011131.1748298-2-fvdpol%40gmail.com


@Takashi, please let me know if the changes made to reduce repetative
patterns and improving readability are going in the right direction and/or
any further comments/observations.

Appreciate any feedback,
Hope to get ready for a v4 patch next weekend.

Best regards,
Frank.