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Message-ID: <20251230082336.3308403-8-professorjonny98@gmail.com>
Date: Tue, 30 Dec 2025 21:23:20 +1300
From: Jonathan Brophy <professorjonny98@...il.com>
To: lee Jones <lee@...nel.org>,
Pavel Machek <pavel@...nel.org>,
Andriy Shevencho <andriy.shevchenko@...ux.intel.com>,
Jonathan Brophy <professor_jonny@...mail.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Radoslav Tsvetkov <rtsvetkov@...dotech.eu>
Cc: devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-leds@...r.kernel.org
Subject: [PATCH v5 7/7] leds: Add virtual LED group driver with priority arbitration
From: Jonathan Brophy <professor_jonny@...mail.com>
Add a driver that implements virtual LED groups with priority-based
arbitration for shared physical LEDs. The driver provides a multicolor
LED interface while solving the coordination problem when multiple
subsystems need to control the same physical LEDs.
Key features:
Winner-takes-all arbitration:
- Only virtual LEDs with brightness > 0 participate
- Highest priority wins (sequence number tie-breaking)
- Winner controls ALL physical LEDs
- Non-winner LEDs are turned off
Multicolor LED ABI support:
- Full compliance with standard multicolor LED interface
- Deterministic channel ordering by LED_COLOR_ID
- Two modes: multicolor (dynamic) and standard (fixed-color)
- Per-channel intensity and master brightness control
Memory optimization:
- Conditional debug compilation (~30% size reduction when disabled)
- Pre-allocated arbitration buffers
- Efficient O(1) physical LED lookup via XArray
- ~200 bytes per virtual LED in production builds
Locking design:
- Hierarchical lock acquisition order prevents deadlocks
- Lock-free arbitration with atomic sequence numbers
- Temporary lock release during hardware I/O to allow concurrency
Hardware support:
- GPIO, PWM, I2C, and SPI LED devices
- Automatic physical LED discovery and claiming
- Global ownership tracking prevents conflicts
- Power management with suspend/resume
Debugfs telemetry (CONFIG_DEBUG_FS):
- Arbitration statistics and latency metrics
- Per-LED win/loss counters
- Physical LED state inspection
- Stress testing interface
Module parameters:
- use_gamma_correction: Perceptual brightness (gamma 2.2)
- update_delay_us: Rate limiting for slow buses
- max_phys_leds: Buffer capacity (default 64)
- enable_update_batching: 10ms coalescing for rapid changes
Typical use cases:
- System status with boot/error priority levels
- RGB lighting with coordinated control
- Multi-element LED arrays (rings, strips)
Co-developed-by: Radoslav Tsvetkov <rtsvetkov@...dotech.eu>
Signed-off-by: Radoslav Tsvetkov <rtsvetkov@...dotech.eu>
Tested-by: Jonathan Brophy <professor_jonny@...mail.com>
Signed-off-by: Jonathan Brophy <professor_jonny@...mail.com>
---
drivers/leds/rgb/leds-group-virtualcolor.c | 3360 ++++++++++++++++++++
1 file changed, 3360 insertions(+)
create mode 100644 drivers/leds/rgb/leds-group-virtualcolor.c
diff --git a/drivers/leds/rgb/leds-group-virtualcolor.c b/drivers/leds/rgb/leds-group-virtualcolor.c
new file mode 100644
index 000000000000..3f8f98f23344
--- /dev/null
+++ b/drivers/leds/rgb/leds-group-virtualcolor.c
@@ -0,0 +1,3360 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * leds-group-virtualcolor.c - Virtual grouped LED driver with Multicolor ABI
+ *
+ * This driver is fully compliant with the multicolor LED ABI.
+ * It adds a policy layer to arbitrate shared physical LEDs,
+ * a problem not addressed by the LED core, without changing userspace-visible behavior.
+ * these additional extensions introduce new capabilities, such as:
+ *
+ * - Priority-based arbitration for shared physical LED ownership
+ * - Sequence/timestamp tie-breaking for deterministic conflict resolution
+ * - Runtime reconfiguration of shared channels for grouped LEDs
+ * - Atomic multi-device updates to ensure consistency
+ * - Group-wide brightness propagation and scaling
+ * - Support for arbitrated updates from multiple virtual LEDs to shared physical LEDs
+ * - Dynamic reallocation and resolution of conflicting virtual-to-physical mapping
+ *
+ * Priority-based arbitration resolves conflicts when multiple virtual LEDs
+ * reference the same physical LEDs. Arbitration rules are:
+ * 1. Priority value of led (higher wins)
+ * 2. Priority value of virtual controller (higher wins)
+ * 3. Sequence number for tie-breaking (most recent wins)
+ * 4. Winner-takes-all: ONE virtual LED controls ALL physical LEDs
+ *
+ * MC channel multipliers add advanced capabilities to LEDs, including:
+ * - Adjusting the relative brightness levels of different color channels
+ * - Normalizing output across different hardware vendors and physical configurations
+ * - Manipulating color temperature by changing the balance between channels
+ * - Avoiding overdriving specific channels unnecessarily
+ * - Mapping physical LEDs to application-specific color spaces and intensities
+ * - Emulating single fixed-color LEDs from multicolor LEDs
+ * - Dynamic reconfiguration of output characteristics
+ * - Capping brightness levels to suit specific use cases
+ *
+ * Winner-Takes-All Arbitration:
+ * - Only vLEDs with brightness > 0 participate
+ * - Highest priority wins (ties broken by sequence number)
+ * - Winner controls ALL physical LEDs
+ * - Physical LEDs not used by the winner are turned off
+ *
+ * Locking hierarchy (must be acquired in this order):
+ * 1. vcolor_controller.lock (per-controller) ← Controller FIRST
+ * 2. global_owner_rwsem (global) ← Global SECOND
+ * 3. virtual_led.lock (per-vLED)
+ *
+ * Never hold vLED locks during arbitration to avoid deadlock.
+ * Arbitration copies vLED state under the vLED lock, then releases locks
+ * before proceeding to core processing.
+ *
+ * Device Tree Dependency:
+ * This driver requires Device Tree (CONFIG_OF) due to LED phandle resolution.
+ * GPIO LEDs, in particular, rely on OF-specific APIs, as they lack full
+ * fwnode support. Minimal `CONFIG_OF` usage ensures easy migration to ACPI
+ * when fwnode abstraction improves. Key operations include:
+ * - `of_led_get()` - Called for LED phandle resolution within the single
+ * bridge function `vcolor_led_from_fwnode()`.
+ * - `device_for_each_child_node()` for child iteration
+ * - `fwnode_property_*()` for property access
+ * - `fwnode_handle_get/put()` for reference management
+ *
+ * By isolating OF dependency in the bridge function, migration to
+ * `fwnode_led_get()` will be straightforward when supported by the LED subsystem.
+ *
+ * Author: Jonathan Brophy <professor_jonny@...mail.com>
+ */
+
+#include <dt-bindings/leds/common.h>
+
+#include <linux/atomic.h>
+#include <linux/compiler.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/ktime.h>
+#include <linux/leds.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#ifdef CONFIG_DEBUG_FS
+ #include <linux/random.h>
+#endif
+#include <linux/ratelimit.h>
+#include <linux/rwsem.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+#include <linux/xarray.h>
+
+#define DRIVER_NAME "leds-group-virtualcolor"
+#define DRIVER_VERSION "4"
+#define VLED_DEBUGFS_DIR DRIVER_NAME
+#define MAX_PHYS_LEDS_DEFAULT 64
+#define UPDATE_BATCH_DELAY_MS 10
+#define DEFAULT_UPDATE_RATE_LIMIT 100 /* Updates per second per vLED */
+#define PRIORITY_MAX INT_MAX
+#define VLED_SNAPSHOT_DEFAULT 32 /* Typical system has <32 vLEDs per controller */
+
+#ifdef CONFIG_DEBUG_FS
+ #define MAX_DEBUGFS_NAME 96 /* Sized for "function:color-multicolor-##" + vLED name */
+#endif
+
+#ifdef CONFIG_LOCKDEP
+ #define assert_controller_locked(lvc) lockdep_assert_held(&(lvc)->lock)
+ #define assert_vled_locked(vled) lockdep_assert_held(&(vled)->lock)
+#else
+#define assert_controller_locked(lvc) ((void)(lvc))
+#define assert_vled_locked(vled) ((void)(vled))
+#endif
+
+static inline bool is_valid_led_cdev(struct led_classdev *cdev)
+{
+ if (!cdev)
+ return false;
+ if (!cdev->brightness_set && !cdev->brightness_set_blocking)
+ return false;
+ return true;
+}
+
+/* Structured logging macros */
+#define ctrl_err(lvc, fmt, ...) \
+ dev_err(&(lvc)->pdev->dev, "[CTRL] " fmt, ##__VA_ARGS__)
+
+#define ctrl_warn(lvc, fmt, ...) \
+ dev_warn(&(lvc)->pdev->dev, "[CTRL] " fmt, ##__VA_ARGS__)
+
+#define ctrl_info(lvc, fmt, ...) \
+ dev_info(&(lvc)->pdev->dev, "[CTRL] " fmt, ##__VA_ARGS__)
+
+#define ctrl_dbg(lvc, fmt, ...) \
+ dev_dbg(&(lvc)->pdev->dev, "[CTRL] " fmt, ##__VA_ARGS__)
+
+#define arb_err(lvc, fmt, ...) \
+ dev_err_ratelimited(&(lvc)->pdev->dev, "[ARB] " fmt, ##__VA_ARGS__)
+
+#define vled_err(vled, fmt, ...) \
+ dev_err(&(vled)->ctrl->pdev->dev, "[vLED:%s] " fmt, (vled)->name, ##__VA_ARGS__)
+
+static_assert(sizeof(void *) <= sizeof(unsigned long),
+ "XArray keys require pointer size <= unsigned long");
+
+/* Module parameters */
+#ifdef CONFIG_DEBUG_FS
+static bool enable_debugfs = true;
+#else
+static bool enable_debugfs;
+#endif
+
+static bool use_gamma_correction;
+static unsigned int update_delay_us;
+static unsigned int max_phys_leds = MAX_PHYS_LEDS_DEFAULT;
+static bool enable_update_batching;
+
+/* LED mode enumeration */
+enum vled_mode {
+ VLED_MODE_MULTICOLOR = 0,
+ VLED_MODE_STANDARD = 1,
+};
+
+struct vcolor_controller;
+
+struct mc_channel {
+ u8 color_id;
+ u8 num_leds;
+ struct led_classdev **leds;
+ struct device **led_devs;
+ u8 intensity;
+ u8 scale;
+};
+
+struct phys_led_entry {
+ /* HOT PATH */
+ struct led_classdev *cdev;
+ u8 chosen_brightness;
+ s32 chosen_priority;
+ u64 chosen_sequence;
+ struct kref refcount;
+ unsigned int list_index;
+
+ /* COLD PATH */
+ struct device *dev;
+ struct list_head list;
+#ifdef CONFIG_DEBUG_FS
+ char winner_name[MAX_DEBUGFS_NAME];
+#endif
+};
+
+struct update_buffer {
+ struct phys_led_entry **entries;
+ u8 *brightness;
+ unsigned int capacity;
+ unsigned int max_capacity;
+};
+
+struct arbitration_buffers {
+ u8 *intensities;
+ u8 *scales;
+ unsigned int capacity;
+};
+
+static DEFINE_XARRAY(global_owner_xa);
+static DECLARE_RWSEM(global_owner_rwsem);
+
+struct global_phys_owner {
+ struct platform_device *owner_pdev;
+};
+
+
+/*
+ * struct virtual_led - Virtual LED with priority-based arbitration
+ * @cdev: LED class device
+ * @priority: Arbitration priority (higher wins)
+ * @name: LED name (assigned by LED core)
+ * @channels: Array of color channels
+ * @num_channels: Number of color channels (max 255, but dirty tracking limited to 32)
+ * @lock: Protects vLED state during updates
+ * @list: Entry in controller's vLED list
+ * @fwnode: Firmware node for DT parsing
+ * @ctrl: Parent controller
+ * @cdev_registered: LED class device registration status
+ * @intensity_ratelimit: Rate limiter for intensity updates
+ * @arb_bufs: Pre-allocated buffers for arbitration
+ * @mode: Operating mode (MULTICOLOR or STANDARD)
+ * @refcount: Reference counter
+ * @sequence: Monotonic sequence number for tie-breaking
+ * All channels are processed during each arbitration cycle for simplicity.
+ *
+ */
+struct virtual_led {
+ struct led_classdev cdev;
+ s32 priority;
+ const char *name;
+ struct mc_channel *channels;
+ u8 num_channels;
+ struct mutex lock;
+ struct list_head list;
+ struct fwnode_handle *fwnode;
+ struct vcolor_controller *ctrl;
+ bool cdev_registered;
+ struct ratelimit_state intensity_ratelimit;
+ struct arbitration_buffers arb_bufs;
+ enum vled_mode mode;
+ struct kref refcount;
+ u64 sequence;
+
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *debugfs_dir;
+ u64 brightness_set_count;
+ u64 intensity_update_count;
+ u64 arbitration_wins;
+ u64 arbitration_losses;
+ u64 arbitration_participations;
+ u64 buffer_allocation_failures;
+ u64 intensity_parse_errors;
+ u64 ratelimit_drops;
+ u64 blink_requests;
+#endif
+};
+
+struct vcolor_controller {
+ struct list_head leds;
+ struct mutex lock;
+ struct list_head phys_leds;
+ struct xarray phys_xa;
+ struct platform_device *pdev;
+ struct update_buffer update_buf;
+ /* Pre-allocated arbitration buffers */
+ struct virtual_led **vled_snapshot;
+ unsigned int vled_snapshot_capacity;
+ struct phys_led_entry **ple_snapshot;
+ unsigned int ple_snapshot_capacity;
+ bool *ple_usage_bitmap;
+ unsigned int ple_usage_bitmap_capacity;
+ bool suspended;
+ atomic_t rebuilding;
+ bool needs_arbitration;
+ unsigned int phys_led_count;
+ atomic_t removing;
+ struct delayed_work update_work;
+ atomic_t pending_updates;
+ atomic64_t global_sequence;
+ bool first_arbitration;
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *debugfs_root;
+ u64 arbitration_count;
+ u64 update_count;
+ atomic64_t allocation_failures;
+ atomic64_t update_buffer_overflows;
+ atomic64_t ratelimit_hits;
+ u64 arb_latency_min_ns;
+ u64 arb_latency_max_ns;
+ u64 arb_latency_total_ns;
+ u64 arb_latency_count;
+ ktime_t last_update;
+#endif
+};
+
+/* Forward declarations */
+static void controller_rebuild_phys_leds(struct vcolor_controller *lvc);
+static void controller_destroy_phys_list(struct vcolor_controller *lvc);
+static void controller_run_arbitration_and_update(struct vcolor_controller *lvc);
+static void phys_led_entry_release(struct kref *ref);
+static void virtual_led_release(struct kref *ref);
+
+static inline unsigned long get_stable_led_key(struct led_classdev *cdev)
+{
+ if (!cdev)
+ return 0;
+
+ /* GPIO LEDs don't have dev - use cdev pointer as key */
+ if (cdev->dev)
+ return (unsigned long)cdev->dev;
+ else
+ return (unsigned long)cdev;
+}
+
+static inline struct virtual_led *virtual_led_get(struct virtual_led *vled)
+{
+ if (vled)
+ kref_get(&vled->refcount);
+ return vled;
+}
+
+static inline void virtual_led_put(struct virtual_led *vled)
+{
+ if (vled)
+ kref_put(&vled->refcount, virtual_led_release);
+}
+
+static inline bool controller_safe_arbitrate(struct vcolor_controller *lvc)
+{
+ bool ran;
+
+ if (!lvc)
+ return false;
+
+ /* Fast path: avoid lock acquisition if nothing to do */
+ if (atomic_read(&lvc->removing))
+ return false;
+
+ /* FIX: Queue deferred arbitration if rebuilding */
+ if (atomic_read(&lvc->rebuilding)) {
+ lvc->needs_arbitration = true;
+ return false;
+ }
+
+ mutex_lock(&lvc->lock);
+
+ /* Check suspended under lock to prevent suspend race */
+ ran = false;
+ if (!lvc->suspended && !atomic_read(&lvc->rebuilding) &&
+ device_is_registered(&lvc->pdev->dev)) {
+ controller_run_arbitration_and_update(lvc);
+ ran = true;
+ }
+
+ /* FIX: Lock was released by controller_run_arbitration_and_update */
+ return ran;
+}
+
+
+/*
+ * parse_leds_fwnode_array - Parse LED references using fwnode APIs
+ * @dev: Device for logging and memory allocation
+ * @fwnode: Firmware node containing LED references
+ * @propname: Property name (e.g., "leds")
+ * @out_leds: Output array of LED classdev pointers
+ * @out_devs: Output array of device pointers (may contain NULLs for GPIO LEDs)
+ * @out_count: Number of LEDs found
+ *
+ * Uses fwnode APIs for property traversal, with a single OF bridge for LED resolution.
+ * This pattern mirrors V4L2's approach and makes future fwnode_led_get() migration trivial.
+ */
+static int parse_leds_fwnode_array(struct device *dev,
+ const struct fwnode_handle *fwnode,
+ const char *propname,
+ struct led_classdev ***out_leds,
+ struct device ***out_devs,
+ u8 *out_count)
+{
+ struct fwnode_reference_args args;
+ int count, idx, valid, i;
+ struct led_classdev **leds;
+ struct device **devs;
+ struct led_classdev *cdev;
+ struct device *led_dev;
+ int ret;
+
+ *out_leds = NULL;
+ *out_devs = NULL;
+ *out_count = 0;
+
+ /* Count phandle references using generic fwnode API */
+ count = 0;
+ while (fwnode_property_get_reference_args(fwnode, propname,
+ NULL, 0, count, &args) == 0) {
+ fwnode_handle_put(args.fwnode);
+ count++;
+ }
+
+ if (count <= 0)
+ return 0;
+
+ /* Allocate temporary arrays for LED/device pointers */
+ leds = kcalloc(count, sizeof(*leds), GFP_KERNEL);
+ if (!leds)
+ return -ENOMEM;
+
+ devs = kcalloc(count, sizeof(*devs), GFP_KERNEL);
+ if (!devs) {
+ kfree(leds);
+ return -ENOMEM;
+ }
+
+ /* Iterate through each LED reference and PACK valid entries */
+ valid = 0;
+ for (idx = 0; idx < count; idx++) {
+
+ /*Resolve LED from fwnode using index.*/
+ cdev = fwnode_led_get(fwnode, idx, &led_dev);
+
+ if (IS_ERR(cdev)) {
+ ret = PTR_ERR(cdev);
+
+ /* Handle deferred probe - cleanup and return immediately */
+ if (ret == -EPROBE_DEFER) {
+ dev_info(dev, "LED %d not ready yet (EPROBE_DEFER), will retry\n", idx);
+
+ /* Release all previously acquired LEDs and devices */
+ for (i = 0; i < valid; i++) {
+ if (leds[i])
+ led_put(leds[i]);
+ if (devs[i])
+ put_device(devs[i]);
+ }
+
+ kfree(leds);
+ kfree(devs);
+ return -EPROBE_DEFER;
+ }
+
+ /* Other errors - log and skip this LED */
+ dev_warn(dev, "Failed to resolve LED %d: %d\n", idx, ret);
+ continue;
+ }
+
+ /* Store valid LED in PACKED position */
+ if (is_valid_led_cdev(cdev)) {
+ leds[valid] = cdev; /* Pack at 'valid' index, not 'idx' */
+ devs[valid] = led_dev; /* May be NULL for GPIO LEDs */
+ valid++;
+ } else {
+ dev_warn(dev, "LED %d is not valid (no brightness_set method)\n", idx);
+ led_put(cdev);
+ if (led_dev)
+ put_device(led_dev);
+ }
+ }
+
+ /* Check if we got any valid LEDs */
+ if (valid == 0) {
+ dev_warn(dev, "Property '%s': none of %d LED(s) resolved\n",
+ propname, count);
+ kfree(leds);
+ kfree(devs);
+ return -ENODEV;
+ }
+
+ /* Success - return PACKED arrays to caller */
+ *out_leds = leds;
+ *out_devs = devs;
+ *out_count = (u8)valid;
+
+ return 0;
+}
+
+static int validate_and_set_max_brightness(struct virtual_led *vled)
+{
+ unsigned int i, j;
+ enum led_brightness min_max_brightness = LED_FULL;
+
+ /*
+ * For multicolor mode, virtual LED always exposes full 8-bit range.
+ * Scaling happens automatically in scale_intensity_by_brightness().
+ */
+ if (vled->mode == VLED_MODE_MULTICOLOR) {
+ vled->cdev.max_brightness = LED_FULL;
+ return 0;
+ }
+
+ /*
+ * For standard mode, use minimum of physical LEDs since color is
+ * fixed by multipliers.
+ */
+ for (i = 0; i < vled->num_channels; i++) {
+ for (j = 0; j < vled->channels[i].num_leds; j++) {
+ enum led_brightness max_brightness;
+
+ if (!vled->channels[i].leds[j])
+ continue;
+
+ max_brightness = vled->channels[i].leds[j]->max_brightness;
+ if (max_brightness == 0)
+ max_brightness = LED_FULL;
+
+ if (max_brightness < min_max_brightness)
+ min_max_brightness = max_brightness;
+ }
+ }
+
+ if (min_max_brightness < 1)
+ min_max_brightness = 1;
+
+ vled->cdev.max_brightness = min_max_brightness;
+ return 0;
+}
+
+static void global_release_all_for_pdev(struct platform_device *pdev)
+{
+ unsigned long index;
+ unsigned long released;
+ struct global_phys_owner *gpo;
+
+ down_write(&global_owner_rwsem);
+
+ released = 0;
+
+ /*
+ * FIXED: Use xa_for_each() + xa_erase() instead of XA_STATE + xas_store().
+ *
+ * The old code used xas_store(&xas, NULL) inside xas_for_each(), which
+ * corrupts the iterator state and can skip entries or cause crashes.
+ *
+ * xa_for_each() is safe to use with xa_erase() because:
+ * 1. xa_for_each is a simple macro that doesn't maintain complex state
+ * 2. xa_erase() is designed to work during iteration
+ * 3. The iterator naturally moves to the next valid entry
+ */
+ xa_for_each(&global_owner_xa, index, gpo) {
+ if (gpo && gpo->owner_pdev == pdev) {
+ xa_erase(&global_owner_xa, index);
+ kfree(gpo);
+ released++;
+ }
+ }
+
+ up_write(&global_owner_rwsem);
+
+ if (released) {
+ dev_info(&pdev->dev, "Released %lu physical LED ownership claims\n",
+ released);
+ }
+}
+
+static void phys_led_entry_release(struct kref *ref)
+{
+ struct phys_led_entry *ple;
+
+ ple = container_of(ref, struct phys_led_entry, refcount);
+
+ if (ple->dev)
+ put_device(ple->dev);
+
+ kfree(ple);
+}
+
+static inline struct phys_led_entry *phys_led_entry_get(
+ struct phys_led_entry *ple)
+{
+ if (ple)
+ kref_get(&ple->refcount);
+ return ple;
+}
+
+static inline void phys_led_entry_put(struct phys_led_entry *ple)
+{
+ if (ple)
+ kref_put(&ple->refcount, phys_led_entry_release);
+}
+
+/*
+ * claim_physical_led - Claim ownership of a physical LED
+ *
+ * LOCKING: Acquires locks in this order (matching hierarchy):
+ * 1. lvc->lock (controller) - acquired FIRST
+ * 2. global_owner_rwsem (global) - acquired SECOND
+ *
+ * This order prevents AB-BA deadlock. Caller must NOT hold lvc->lock on entry.
+ */
+static bool claim_physical_led(struct vcolor_controller *lvc,
+ struct led_classdev *cdev,
+ struct device *dev,
+ struct phys_led_entry **out_ple)
+{
+ struct global_phys_owner *gpo;
+ struct phys_led_entry *ple = NULL;
+ void *ret_ptr;
+ bool success = false;
+ bool newly_claimed_global = false;
+ unsigned long key;
+
+ *out_ple = NULL;
+
+ if (!cdev)
+ return false;
+
+ key = get_stable_led_key(cdev);
+ if (!key) {
+ ctrl_err(lvc, "Failed to get stable key for LED '%s'\n",
+ cdev->name ? cdev->name : "(unnamed)");
+ return false;
+ }
+
+ /*
+ * FIXED: Acquire controller lock FIRST, then check removal flag.
+ * This eliminates TOCTOU race - once we hold the lock, removal
+ * cannot proceed past the rebuilding wait.
+ */
+ mutex_lock(&lvc->lock);
+
+ /* Single authoritative check under lock */
+ if (atomic_read(&lvc->removing)) {
+ mutex_unlock(&lvc->lock);
+ return false;
+ }
+
+ down_write(&global_owner_rwsem);
+
+ gpo = xa_load(&global_owner_xa, key);
+ if (xa_is_value(gpo)) {
+ ctrl_err(lvc, "Invalid XArray entry for LED '%s'\n", cdev->name);
+ goto out_unlock;
+ }
+
+ if (gpo && gpo->owner_pdev != lvc->pdev) {
+ ctrl_warn(lvc, "Physical LED '%s' already claimed by another controller\n",
+ cdev->name);
+ goto out_unlock;
+ }
+
+ if (xa_load(&lvc->phys_xa, key)) {
+ ctrl_dbg(lvc, "LED '%s' already claimed locally, skipping duplicate\n",
+ cdev->name);
+ goto out_unlock;
+ }
+
+ ple = kzalloc(sizeof(*ple), GFP_KERNEL);
+ if (!ple) {
+#ifdef CONFIG_DEBUG_FS
+ ctrl_err(lvc, "Failed to allocate phys_led_entry for '%s'\n",
+ cdev->name);
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ goto out_unlock;
+ }
+
+ kref_init(&ple->refcount);
+ ple->cdev = cdev;
+ ple->dev = dev;
+ if (dev)
+ get_device(dev);
+ ple->chosen_brightness = 0;
+ ple->chosen_priority = -1;
+ ple->chosen_sequence = 0;
+#ifdef CONFIG_DEBUG_FS
+ ple->winner_name[0] = '\0';
+#endif
+
+ if (!gpo) {
+ gpo = kzalloc(sizeof(*gpo), GFP_KERNEL);
+ if (!gpo) {
+#ifdef CONFIG_DEBUG_FS
+ ctrl_err(lvc, "Failed to allocate ownership record for LED '%s'\n",
+ cdev->name);
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ goto out_unlock;
+ }
+
+ gpo->owner_pdev = lvc->pdev;
+ ret_ptr = xa_store(&global_owner_xa, key, gpo, GFP_KERNEL);
+
+ if (xa_is_err(ret_ptr)) {
+ ctrl_err(lvc, "Failed to register global ownership for LED '%s': %ld\n",
+ cdev->name, PTR_ERR(ret_ptr));
+ kfree(gpo);
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ goto out_unlock;
+ }
+
+ newly_claimed_global = true;
+ }
+
+ ret_ptr = xa_store(&lvc->phys_xa, key, ple, GFP_KERNEL);
+ if (xa_is_err(ret_ptr)) {
+ ctrl_err(lvc, "Failed to store phys_led_entry '%s' in xarray: %ld\n",
+ cdev->name, PTR_ERR(ret_ptr));
+
+ if (newly_claimed_global) {
+ gpo = xa_erase(&global_owner_xa, key);
+ if (gpo && !xa_is_value(gpo)) {
+ ctrl_dbg(lvc, "Cleaned up leaked global ownership for '%s' after local store failure\n",
+ cdev->name);
+ kfree(gpo);
+ }
+ }
+
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ goto out_unlock;
+ }
+
+ list_add_tail(&ple->list, &lvc->phys_leds);
+ lvc->phys_led_count++;
+ *out_ple = ple;
+ success = true;
+
+out_unlock:
+ /* FIXED: Clean up XArray BEFORE releasing locks */
+ if (!success && ple) {
+ void *stored = xa_load(&lvc->phys_xa, key);
+
+ if (stored == ple)
+ xa_erase(&lvc->phys_xa, key);
+ }
+
+ /* Release locks in reverse order */
+ up_write(&global_owner_rwsem);
+ mutex_unlock(&lvc->lock);
+
+ /* Safe cleanup - removed from XArray first */
+ if (!success && ple)
+ phys_led_entry_put(ple);
+
+ return success;
+}
+
+static void add_led_group_to_phys_list(struct vcolor_controller *lvc,
+ struct led_classdev **leds,
+ struct device **devs,
+ unsigned int count)
+{
+ unsigned int i;
+ struct phys_led_entry *ple;
+
+ for (i = 0; i < count; i++) {
+ if (!leds || !leds[i])
+ continue;
+
+ claim_physical_led(lvc, leds[i], devs ? devs[i] : NULL, &ple);
+ }
+}
+
+static void controller_destroy_phys_list(struct vcolor_controller *lvc)
+{
+ struct phys_led_entry *ple, *tmp;
+ unsigned long key;
+
+ assert_controller_locked(lvc);
+
+ list_for_each_entry_safe(ple, tmp, &lvc->phys_leds, list) {
+ list_del(&ple->list);
+
+ if (ple->cdev) {
+ key = get_stable_led_key(ple->cdev);
+ if (key)
+ xa_erase(&lvc->phys_xa, key);
+ ple->cdev = NULL;
+ }
+
+ phys_led_entry_put(ple);
+ }
+
+ INIT_LIST_HEAD(&lvc->phys_leds);
+ lvc->phys_led_count = 0;
+}
+
+/*
+ * controller_rebuild_phys_leds - Rebuild physical LED ownership mappings
+ * @lvc: Controller instance
+ *
+ * LOCKING: Must be called with lvc->lock held.
+ *
+ * IMPORTANT: This function TEMPORARILY DROPS lvc->lock during LED reference
+ * acquisition to avoid holding the lock during potentially blocking operations.
+ * The atomic_rebuilding flag prevents concurrent arbitration while the lock
+ * is dropped.
+ *
+ * Call sequence:
+ * 1. Assert lvc->lock is held
+ * 2. Set atomic_rebuilding = 1
+ * 3. Take snapshot of vLEDs with refcounts
+ * 4. Destroy existing physical LED mappings
+ * 5. DROP LOCK (intentional - see locking hierarchy comment at top of file)
+ * 6. Process vLED channels and claim physical LEDs
+ * 7. REACQUIRE LOCK
+ * 8. Assign list indices for O(1) arbitration lookup
+ * 9. Clear atomic_rebuilding = 0
+ * 10. Run arbitration to apply new state
+ *
+ * The lock drop is necessary because:
+ * - add_led_group_to_phys_list() calls claim_physical_led()
+ * - claim_physical_led() acquires global_owner_rwsem (higher in hierarchy)
+ * - Holding lvc->lock during this would violate lock ordering
+ */
+static void controller_rebuild_phys_leds(struct vcolor_controller *lvc)
+{
+ struct virtual_led *vled, **vled_snapshot;
+ unsigned int i, j, vled_count, actual_count;
+ bool needs_free = false;
+
+ assert_controller_locked(lvc);
+
+ atomic_set(&lvc->rebuilding, 1);
+
+ /* Count vLEDs first */
+ vled_count = 0;
+ list_for_each_entry(vled, &lvc->leds, list)
+ vled_count++;
+
+ /* Explicitly turn off LEDs when no vLEDs exist */
+ if (vled_count == 0) {
+ struct phys_led_entry *ple;
+
+ /* Turn off all physical LEDs before destroying list */
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (ple->cdev) {
+ if (ple->cdev->brightness_set_blocking)
+ ple->cdev->brightness_set_blocking(ple->cdev, 0);
+ else if (ple->cdev->brightness_set)
+ ple->cdev->brightness_set(ple->cdev, 0);
+ ple->cdev->brightness = 0;
+ }
+ }
+
+ /* Safe to destroy when no vLEDs exist */
+ controller_destroy_phys_list(lvc);
+ xa_destroy(&lvc->phys_xa);
+ xa_init(&lvc->phys_xa);
+ atomic_set(&lvc->rebuilding, 0);
+ return;
+ }
+
+ /* Allocate snapshot BEFORE destroying existing state */
+ if (vled_count > lvc->vled_snapshot_capacity) {
+ ctrl_warn(lvc,
+ "vLED count %u exceeds snapshot capacity %u, using dynamic allocation\n",
+ vled_count, lvc->vled_snapshot_capacity);
+ vled_snapshot = kcalloc(vled_count, sizeof(*vled_snapshot), GFP_KERNEL);
+ if (!vled_snapshot) {
+ ctrl_err(lvc, "Failed to allocate vled snapshot for rebuild (OOM) - keeping existing state\n");
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ atomic_set(&lvc->rebuilding, 0);
+ return;
+ }
+ needs_free = true;
+ } else {
+ vled_snapshot = lvc->vled_snapshot;
+ needs_free = false;
+ }
+
+ /* Copy vLED pointers with refcounts BEFORE destroying state */
+ actual_count = 0;
+ list_for_each_entry(vled, &lvc->leds, list) {
+ if (actual_count >= vled_count) {
+ ctrl_warn(lvc, "vLED count increased during snapshot! Expected %u\n", vled_count);
+ break;
+ }
+ vled_snapshot[actual_count++] = virtual_led_get(vled);
+ }
+
+ /* Fail hard if count increased (race condition) */
+ if (actual_count > vled_count) {
+ ctrl_err(lvc, "vLED count INCREASED during snapshot (%u -> %u) - aborting rebuild\n",
+ vled_count, actual_count);
+ for (i = 0; i < actual_count; i++)
+ virtual_led_put(vled_snapshot[i]);
+ if (needs_free)
+ kfree(vled_snapshot);
+ atomic_set(&lvc->rebuilding, 0);
+ return;
+ }
+
+ /* Now safe to destroy existing state */
+ controller_destroy_phys_list(lvc);
+ xa_destroy(&lvc->phys_xa);
+ xa_init(&lvc->phys_xa);
+
+ /* Check removal flag BEFORE dropping lock */
+ if (atomic_read(&lvc->removing)) {
+ atomic_set(&lvc->rebuilding, 0);
+ /* Release snapshot references */
+ for (i = 0; i < actual_count; i++) {
+ if (vled_snapshot[i])
+ virtual_led_put(vled_snapshot[i]);
+ }
+ if (needs_free)
+ kfree(vled_snapshot);
+ return;
+ }
+
+ mutex_unlock(&lvc->lock);
+
+ /* Process all vLEDs outside lock */
+ for (i = 0; i < actual_count; i++) {
+ vled = vled_snapshot[i];
+ if (!vled)
+ continue;
+
+ /* Double-check removal flag */
+ if (atomic_read(&lvc->removing)) {
+ for (; i < actual_count; i++) {
+ if (vled_snapshot[i])
+ virtual_led_put(vled_snapshot[i]);
+ }
+ goto out_cleanup;
+ }
+
+ for (j = 0; j < vled->num_channels; j++) {
+ add_led_group_to_phys_list(lvc, vled->channels[j].leds,
+ vled->channels[j].led_devs,
+ vled->channels[j].num_leds);
+ }
+
+ virtual_led_put(vled);
+ vled_snapshot[i] = NULL;
+ }
+
+out_cleanup:
+ if (needs_free)
+ kfree(vled_snapshot);
+
+ mutex_lock(&lvc->lock);
+
+ /* Assign list indices for O(1) lookup during arbitration */
+ {
+ unsigned int idx = 0;
+ struct phys_led_entry *ple_temp;
+
+ list_for_each_entry(ple_temp, &lvc->phys_leds, list) {
+ ple_temp->list_index = idx++;
+ }
+ }
+
+ /* FIX #4: Run arbitration BEFORE clearing rebuilding flag */
+ if (!atomic_read(&lvc->removing))
+ controller_run_arbitration_and_update(lvc);
+
+ /* FIX #2: Check for deferred arbitration */
+ if (lvc->needs_arbitration && !atomic_read(&lvc->removing)) {
+ lvc->needs_arbitration = false;
+ controller_run_arbitration_and_update(lvc);
+ }
+
+ /* FIX #4: Clear rebuilding flag AFTER arbitration completes */
+ atomic_set(&lvc->rebuilding, 0);
+}
+
+static const u8 gamma_table[256] = {
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
+ 4, 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 13, 13, 14,
+ 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 22, 22, 23, 23, 24, 25, 25, 26,
+ 26, 27, 28, 28, 29, 30, 30, 31, 32, 32, 33, 34, 34, 35, 36, 37, 37, 38, 39, 40, 40, 41,
+ 42, 43, 44, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62,
+ 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 76, 78, 79, 80, 81, 82, 84, 85, 86, 87,
+ 89, 90, 91, 92, 94, 95, 96, 97, 99, 100, 101, 103, 104, 105, 107, 108, 109, 111, 112,
+ 114, 115, 116, 118, 119, 121, 122, 123, 125, 126, 128, 129, 131, 132, 134, 135, 137,
+ 138, 140, 141, 143, 144, 146, 147, 149, 150, 152, 154, 155, 157, 158, 160, 162, 163,
+ 165, 167, 168, 170, 172, 173, 175, 177, 178, 180, 182, 184, 185, 187, 189, 191, 192,
+ 194, 196, 198, 200, 201, 203, 205, 207, 209, 211, 212, 214, 216, 218, 220, 222, 224,
+ 226, 228, 230, 232, 234, 236, 238, 240, 242, 244, 246, 248, 250, 253, 255
+};
+
+static u8 scale_intensity_by_brightness(u8 intensity, u8 global_brightness,
+ u8 max_global_brightness)
+{
+ u32 scaled_val;
+ u8 final_intensity;
+
+ if (max_global_brightness == 0)
+ return 0;
+
+ scaled_val = (u32)intensity * (u32)global_brightness;
+ final_intensity = (u8)clamp_val(scaled_val / max_global_brightness, 0, 255);
+
+ if (use_gamma_correction)
+ final_intensity = gamma_table[final_intensity];
+
+ return final_intensity;
+}
+
+static u8 vled_channel_get_final_intensity(enum vled_mode mode,
+ u8 raw_intensity,
+ u8 scale,
+ enum led_brightness vled_brightness,
+ enum led_brightness vled_max_brightness)
+{
+ u8 intensity = raw_intensity;
+ u16 scaled_val;
+
+ if (mode == VLED_MODE_MULTICOLOR) {
+ if (scale < 255) {
+ scaled_val = ((u16)intensity * (u16)scale) / 255;
+ intensity = (u8)clamp_val(scaled_val, 0, 255);
+ }
+ } else {
+ intensity = scale;
+ }
+
+ return scale_intensity_by_brightness(intensity, vled_brightness,
+ vled_max_brightness);
+}
+
+static void apply_winner_to_channel(struct vcolor_controller *lvc,
+ struct virtual_led *vled,
+ struct led_classdev **leds,
+ unsigned int count,
+ u8 final_intensity)
+{
+ unsigned int i;
+ struct phys_led_entry *ple;
+ unsigned long key;
+#ifdef CONFIG_DEBUG_FS
+ int copy_result;
+#endif
+
+ assert_controller_locked(lvc);
+
+ for (i = 0; i < count; i++) {
+ if (!leds[i])
+ continue;
+
+ key = get_stable_led_key(leds[i]);
+ if (!key)
+ continue;
+
+ ple = xa_load(&lvc->phys_xa, key);
+ if (!ple || xa_is_value(ple))
+ continue;
+
+ /* Winner takes all - no comparison needed */
+ ple->chosen_brightness = final_intensity;
+ ple->chosen_priority = vled->priority;
+ ple->chosen_sequence = vled->sequence;
+
+ #ifdef CONFIG_DEBUG_FS
+ if (vled->name) {
+ copy_result = strscpy(ple->winner_name, vled->name, MAX_DEBUGFS_NAME);
+ if (copy_result < 0) {
+ dev_warn_once(&lvc->pdev->dev,
+ "vLED name truncated in telemetry: '%.32s...'\n",
+ vled->name);
+ }
+ } else {
+ strscpy(ple->winner_name, "(unnamed)", MAX_DEBUGFS_NAME);
+ }
+ #endif
+ }
+}
+
+static void mark_winner_leds(struct vcolor_controller *lvc,
+ struct virtual_led *winner_vled,
+ unsigned int channel_idx,
+ bool *ple_used_by_winner,
+ unsigned int ple_count)
+{
+ unsigned int i;
+
+ for (i = 0; i < winner_vled->channels[channel_idx].num_leds; i++) {
+ unsigned long key;
+ struct phys_led_entry *ple_temp;
+
+ if (!winner_vled->channels[channel_idx].leds[i])
+ continue;
+
+ key = get_stable_led_key(winner_vled->channels[channel_idx].leds[i]);
+ if (!key)
+ continue;
+
+ ple_temp = xa_load(&lvc->phys_xa, key);
+ if (!ple_temp || xa_is_value(ple_temp))
+ continue;
+
+ /* Direct O(1) index lookup instead of O(n) list scan */
+ if (ple_temp->list_index < ple_count)
+ ple_used_by_winner[ple_temp->list_index] = true;
+ }
+}
+
+/*
+ * controller_run_arbitration_and_update - Run winner-takes-all arbitration
+ * @lvc: Controller instance
+ *
+ * Selects the highest priority active vLED and applies its configuration
+ * to all physical LEDs. Non-winner vLEDs are ignored (winner-takes-all).
+ *
+ * Context: Must be called with lvc->lock held.
+ *
+ * CRITICAL LOCKING BEHAVIOR:
+ * - Expects lvc->lock to be held on entry
+ * - Temporarily RELEASES lvc->lock during hardware I/O
+ * - REACQUIRES lvc->lock before return
+ * - Lock state is PRESERVED on return, but shared state may change during unlock
+ *
+ * Rationale for temporary unlock:
+ * Hardware I/O can block for milliseconds. Holding lvc->lock during this
+ * would prevent other vLEDs from updating their state (brightness_set calls).
+ * By releasing the lock during I/O, we allow concurrent operations while
+ * preventing corruption of arbitration results.
+ *
+ * Locking: Acquires vLED locks briefly to snapshot state, then processes
+ * without holding any locks during hardware access.
+ */
+static void controller_run_arbitration_and_update(struct vcolor_controller *lvc)
+{
+ struct phys_led_entry *ple;
+ struct virtual_led *vled;
+ struct virtual_led *winner_vled = NULL;
+ s32 highest_priority = -1;
+ u64 latest_sequence = 0;
+ u8 *intensities;
+ u8 *scales;
+ enum vled_mode mode;
+ unsigned int j;
+ u8 final_intensity;
+ struct phys_led_entry **local_entries;
+ u8 *local_brightness;
+ unsigned int update_count;
+ unsigned int i;
+ u64 vled_seq;
+ enum led_brightness brightness, max_brightness;
+ bool *ple_used_by_winner;
+ unsigned int ple_count;
+
+#ifdef CONFIG_DEBUG_FS
+ ktime_t arb_start, arb_end;
+ u64 arb_duration_ns;
+#endif
+
+ if (!lvc || lvc->suspended || atomic_read(&lvc->removing))
+ return;
+
+ assert_controller_locked(lvc);
+
+ local_entries = lvc->update_buf.entries;
+ local_brightness = lvc->update_buf.brightness;
+
+ if (!local_entries || !local_brightness) {
+ dev_err(&lvc->pdev->dev, "Update buffers not allocated, cannot arbitrate\n");
+ /* FIX: Unlock before returning */
+ mutex_unlock(&lvc->lock);
+ return;
+ }
+
+#ifdef CONFIG_DEBUG_FS
+ arb_start = ktime_get();
+ lvc->arbitration_count++;
+#endif
+
+ /* Count physical LEDs */
+ ple_count = 0;
+ list_for_each_entry(ple, &lvc->phys_leds, list)
+ ple_count++;
+
+ if (ple_count == 0) {
+#ifdef CONFIG_DEBUG_FS
+ arb_end = ktime_get();
+ arb_duration_ns = ktime_to_ns(ktime_sub(arb_end, arb_start));
+ if (lvc->arb_latency_count == 0 || arb_duration_ns < lvc->arb_latency_min_ns)
+ lvc->arb_latency_min_ns = arb_duration_ns;
+ if (arb_duration_ns > lvc->arb_latency_max_ns)
+ lvc->arb_latency_max_ns = arb_duration_ns;
+ lvc->arb_latency_total_ns += arb_duration_ns;
+ lvc->arb_latency_count++;
+#endif
+ /* FIX: Unlock before returning */
+ mutex_unlock(&lvc->lock);
+ return;
+ }
+
+ /* Use pre-allocated bitmap with graceful degradation if too small */
+ if (ple_count > lvc->ple_usage_bitmap_capacity) {
+ dev_warn_once(&lvc->pdev->dev,
+ "Physical LED count %u exceeds bitmap capacity %u - falling back to full LED scan (performance degraded)\n",
+ ple_count, lvc->ple_usage_bitmap_capacity);
+ ple_used_by_winner = NULL;
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ } else {
+ ple_used_by_winner = lvc->ple_usage_bitmap;
+ memset(ple_used_by_winner, 0, ple_count * sizeof(bool));
+ }
+
+ /* Reset arbitration state */
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ ple->chosen_brightness = 0;
+ ple->chosen_priority = -1;
+ ple->chosen_sequence = 0;
+#ifdef CONFIG_DEBUG_FS
+ ple->winner_name[0] = '\0';
+#endif
+ }
+
+ /* STEP 1: Find the ONE active vLED winner (highest priority, latest sequence) */
+ list_for_each_entry(vled, &lvc->leds, list) {
+#ifdef CONFIG_DEBUG_FS
+ vled->arbitration_participations++;
+#endif
+ mutex_lock(&vled->lock);
+
+ brightness = vled->cdev.brightness;
+ vled_seq = vled->sequence;
+
+ mutex_unlock(&vled->lock);
+
+ /* Only vLEDs with brightness > 0 can become winners */
+ if (brightness == 0)
+ continue;
+
+ /* Winner-takes-all: only ONE vLED controls the controller */
+ if (vled->priority > highest_priority) {
+ /* FIX: Release old winner ref and take new ref */
+ if (winner_vled)
+ virtual_led_put(winner_vled);
+ winner_vled = virtual_led_get(vled);
+ highest_priority = vled->priority;
+ latest_sequence = vled_seq;
+ } else if (vled->priority == highest_priority) {
+ s64 seq_diff = (s64)(vled_seq - latest_sequence);
+
+ if (seq_diff > 0) {
+ /* FIX: Release old winner ref and take new ref */
+ if (winner_vled)
+ virtual_led_put(winner_vled);
+ winner_vled = virtual_led_get(vled);
+ latest_sequence = vled_seq;
+ }
+ }
+ }
+
+ /* STEP 2: If no active vLED, all physical LEDs stay at 0 (already set above) */
+ if (!winner_vled) {
+#ifdef CONFIG_DEBUG_FS
+ /* All vLEDs lost (none active) */
+ list_for_each_entry(vled, &lvc->leds, list) {
+ mutex_lock(&vled->lock);
+ if (vled->cdev.brightness == 0)
+ vled->arbitration_losses++;
+ mutex_unlock(&vled->lock);
+ }
+#endif
+ /* Physical LEDs already reset to 0 above */
+ goto collect_updates;
+ }
+
+ /* STEP 3: Apply winner's configuration to all its physical LEDs */
+ mutex_lock(&winner_vled->lock);
+
+ intensities = winner_vled->arb_bufs.intensities;
+ scales = winner_vled->arb_bufs.scales;
+
+ if (!intensities || !scales ||
+ winner_vled->arb_bufs.capacity < winner_vled->num_channels) {
+ mutex_unlock(&winner_vled->lock);
+ arb_err(lvc, "vLED '%s': buffer missing or undersized (cap=%u, need=%u)\n",
+ winner_vled->name ? winner_vled->name : "(unnamed)",
+ winner_vled->arb_bufs.capacity,
+ winner_vled->num_channels);
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->allocation_failures);
+#endif
+ /* FIX: Release winner ref AND unlock before returning */
+ virtual_led_put(winner_vled);
+ mutex_unlock(&lvc->lock);
+ return;
+ }
+
+ /* Snapshot winner's channel data */
+ for (j = 0; j < winner_vled->num_channels; j++) {
+ intensities[j] = winner_vled->channels[j].intensity;
+ scales[j] = winner_vled->channels[j].scale;
+ }
+
+ brightness = winner_vled->cdev.brightness;
+ max_brightness = winner_vled->cdev.max_brightness;
+ mode = winner_vled->mode;
+ vled_seq = winner_vled->sequence;
+
+ mutex_unlock(&winner_vled->lock);
+
+ /* Apply winner to all its channels */
+ for (j = 0; j < winner_vled->num_channels; j++) {
+ final_intensity = vled_channel_get_final_intensity(
+ mode, intensities[j], scales[j], brightness, max_brightness
+ );
+
+ apply_winner_to_channel(lvc, winner_vled,
+ winner_vled->channels[j].leds,
+ winner_vled->channels[j].num_leds,
+ final_intensity);
+
+ /* Mark physical LEDs as used by winner (only if bitmap available) */
+ if (ple_used_by_winner)
+ mark_winner_leds(lvc, winner_vled, j, ple_used_by_winner, ple_count);
+ }
+
+#ifdef CONFIG_DEBUG_FS
+ winner_vled->arbitration_wins++;
+
+ /* Mark all non-winners as losers */
+ list_for_each_entry(vled, &lvc->leds, list) {
+ if (vled != winner_vled) {
+ mutex_lock(&vled->lock);
+ if (vled->cdev.brightness > 0)
+ vled->arbitration_losses++;
+ mutex_unlock(&vled->lock);
+ }
+ }
+#endif
+
+ /* STEP 4: Turn off physical LEDs not used by winner */
+ if (ple_used_by_winner) {
+ /* Fast path: Use bitmap */
+ i = 0;
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (!ple_used_by_winner[i]) {
+ ple->chosen_brightness = 0;
+ ple->chosen_priority = -1;
+ ple->chosen_sequence = 0;
+#ifdef CONFIG_DEBUG_FS
+ ple->winner_name[0] = '\0';
+#endif
+ }
+ i++;
+ }
+ } else {
+ /* Slow path: Full scan when bitmap unavailable (graceful degradation) */
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ bool used_by_winner = false;
+ unsigned int chan_idx, led_idx;
+
+ /* Check if this physical LED is in winner's channel list */
+ for (chan_idx = 0; chan_idx < winner_vled->num_channels && !used_by_winner; chan_idx++) {
+ for (led_idx = 0; led_idx < winner_vled->channels[chan_idx].num_leds; led_idx++) {
+ if (winner_vled->channels[chan_idx].leds[led_idx] == ple->cdev) {
+ used_by_winner = true;
+ break;
+ }
+ }
+ }
+
+ if (!used_by_winner) {
+ ple->chosen_brightness = 0;
+ ple->chosen_priority = -1;
+ ple->chosen_sequence = 0;
+#ifdef CONFIG_DEBUG_FS
+ ple->winner_name[0] = '\0';
+#endif
+ }
+ }
+ }
+
+collect_updates:
+
+ /* Collect LEDs that need updating */
+ update_count = 0;
+
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (!ple->cdev)
+ continue;
+
+ if (lvc->first_arbitration || ple->cdev->brightness != ple->chosen_brightness) {
+ if (update_count >= lvc->update_buf.capacity) {
+ dev_err_ratelimited(&lvc->pdev->dev,
+ "Update buffer overflow: %u LEDs need update, capacity=%u\n",
+ update_count + 1, lvc->update_buf.capacity);
+ dev_err_ratelimited(&lvc->pdev->dev,
+ "CRITICAL: Increase max_phys_leds to %u and reload driver!\n",
+ lvc->phys_led_count + 16);
+ dev_err_ratelimited(&lvc->pdev->dev,
+ "Skipping remaining %u LEDs - will retry next cycle\n",
+ lvc->phys_led_count - update_count);
+#ifdef CONFIG_DEBUG_FS
+ atomic64_inc(&lvc->update_buffer_overflows);
+#endif
+ break;
+ }
+
+ local_entries[update_count] = phys_led_entry_get(ple);
+ local_brightness[update_count] = ple->chosen_brightness;
+ update_count++;
+ }
+ }
+
+ lvc->first_arbitration = false;
+
+#ifdef CONFIG_DEBUG_FS
+ lvc->update_count += update_count;
+ lvc->last_update = ktime_get();
+
+ arb_end = ktime_get();
+ arb_duration_ns = ktime_to_ns(ktime_sub(arb_end, arb_start));
+
+ if (lvc->arb_latency_count == 0 || arb_duration_ns < lvc->arb_latency_min_ns)
+ lvc->arb_latency_min_ns = arb_duration_ns;
+ if (arb_duration_ns > lvc->arb_latency_max_ns)
+ lvc->arb_latency_max_ns = arb_duration_ns;
+
+ if (lvc->arb_latency_total_ns > (U64_MAX - arb_duration_ns) ||
+ lvc->arb_latency_count >= (U64_MAX - 1)) {
+ lvc->arb_latency_total_ns = arb_duration_ns;
+ lvc->arb_latency_count = 1;
+ lvc->arb_latency_min_ns = arb_duration_ns;
+ lvc->arb_latency_max_ns = arb_duration_ns;
+ dev_info(&lvc->pdev->dev,
+ "Arbitration latency statistics reset due to overflow\n");
+ } else {
+ lvc->arb_latency_total_ns += arb_duration_ns;
+ lvc->arb_latency_count++;
+ }
+#endif
+
+ /* FIX: CRITICAL - Unlock BEFORE hardware I/O */
+ mutex_unlock(&lvc->lock);
+
+ /* Hardware I/O outside lock */
+ for (i = 0; i < update_count; i++) {
+ int pm_ret;
+
+ /* Check removing flag and cleanup properly */
+ if (atomic_read(&lvc->removing)) {
+ /* Release all remaining entries including current one */
+ for (; i < update_count; i++) {
+ if (local_entries[i])
+ phys_led_entry_put(local_entries[i]);
+ }
+ /* FIX: Release winner ref before returning - lock already released */
+ if (winner_vled)
+ virtual_led_put(winner_vled);
+ return;
+ }
+
+ ple = local_entries[i];
+ if (!ple || !ple->cdev) {
+ phys_led_entry_put(ple);
+ continue;
+ }
+
+ if (ple->dev && pm_runtime_enabled(ple->dev)) {
+ pm_ret = pm_runtime_get_sync(ple->dev);
+ if (pm_ret < 0) {
+ dev_err_ratelimited(&lvc->pdev->dev,
+ "Failed to power LED '%s': %d\n",
+ ple->cdev->name, pm_ret);
+ pm_runtime_put_noidle(ple->dev);
+ phys_led_entry_put(ple);
+ continue;
+ }
+ }
+
+ if (ple->cdev->brightness_set_blocking)
+ ple->cdev->brightness_set_blocking(ple->cdev, local_brightness[i]);
+ else if (ple->cdev->brightness_set)
+ ple->cdev->brightness_set(ple->cdev, local_brightness[i]);
+
+ /*
+ * Ensure the brightness value is visible to other CPUs after the
+ * hardware update completes. Pairs with smp_load_acquire() in
+ * led_get_brightness() or similar readers.
+ */
+ smp_store_release(&ple->cdev->brightness, local_brightness[i]);
+
+ if (ple->dev && pm_runtime_enabled(ple->dev))
+ pm_runtime_put(ple->dev);
+
+ phys_led_entry_put(ple);
+ }
+
+ if (update_delay_us > 0 && update_count > 0)
+ usleep_range(update_delay_us, update_delay_us + 100);
+
+ /* FIX: Release winner ref at end - lock was already released above */
+ if (winner_vled)
+ virtual_led_put(winner_vled);
+
+ /* FIX: Function now returns with lock UNLOCKED as documented */
+}
+
+static int virtual_led_brightness_set(struct led_classdev *cdev,
+ enum led_brightness brightness)
+{
+ struct virtual_led *vled;
+ struct vcolor_controller *lvc;
+
+ if (!cdev)
+ return -EINVAL;
+
+ vled = container_of(cdev, struct virtual_led, cdev);
+
+ if (!vled || !vled->ctrl)
+ return -ENODEV;
+
+ lvc = vled->ctrl;
+
+ mutex_lock(&vled->lock);
+
+ vled->cdev.brightness = brightness;
+ vled->sequence = atomic64_inc_return(&lvc->global_sequence);
+#ifdef CONFIG_DEBUG_FS
+ vled->brightness_set_count++;
+#endif
+ mutex_unlock(&vled->lock);
+
+ /*
+ * Schedule arbitration based on batching mode.
+ *
+ * When batching is enabled, defer arbitration to reduce overhead
+ * during rapid brightness changes (e.g., software PWM).
+ *
+ * When batching is disabled, run arbitration immediately for
+ * minimal latency.
+ */
+ if (enable_update_batching) {
+ atomic_inc(&lvc->pending_updates);
+ mod_delayed_work(system_wq, &lvc->update_work,
+ msecs_to_jiffies(UPDATE_BATCH_DELAY_MS));
+ } else {
+ controller_safe_arbitrate(lvc);
+ }
+
+ return 0;
+}
+
+/*
+ * virtual_led_blink_set - Configure LED blinking
+ * @cdev: LED class device
+ * @delay_on: Pointer to ON duration in milliseconds
+ * @delay_off: Pointer to OFF duration in milliseconds
+ *
+ * Attempts to enable hardware blink on all physical LEDs.
+ * If any physical LED lacks hardware blink support, returns error
+ * to trigger LED core's automatic software fallback.
+ *
+ * Returns: 0 on success, -EINVAL to request software blink
+ */
+static int virtual_led_blink_set(struct led_classdev *cdev,
+ unsigned long *delay_on,
+ unsigned long *delay_off)
+{
+struct virtual_led *vled = container_of(cdev, struct virtual_led, cdev);
+
+ #ifdef CONFIG_DEBUG_FS
+ vled->blink_requests++;
+ #endif
+
+ /*
+ * Always return -EINVAL to request LED core's software blink.
+ *
+ * Rationale: Hardware blink on physical LEDs would bypass our
+ * arbitration system. When multiple vLEDs compete for the same
+ * physical LED, hardware blink on that LED would continue even
+ * when a higher-priority vLED takes control.
+ *
+ * LED core will handle software blink by calling brightness_set_blocking()
+ * in a timer, which properly goes through our arbitration.
+ */
+ return -EINVAL;
+}
+
+static void deferred_update_worker(struct work_struct *work)
+{
+ struct vcolor_controller *lvc;
+ int pending;
+
+ lvc = container_of(work, struct vcolor_controller, update_work.work);
+
+ /* FIXED: Check removal flag BEFORE doing any work */
+ if (atomic_read(&lvc->removing))
+ return;
+
+ pending = atomic_xchg(&lvc->pending_updates, 0);
+
+ if (pending > 0) {
+ if (!controller_safe_arbitrate(lvc)) {
+ /* Only reschedule if not removing */
+ if (!atomic_read(&lvc->removing)) {
+ atomic_set(&lvc->pending_updates, pending);
+ mod_delayed_work(system_wq, &lvc->update_work,
+ msecs_to_jiffies(UPDATE_BATCH_DELAY_MS));
+ }
+ }
+ }
+}
+
+static ssize_t multi_intensity_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct led_classdev *cdev;
+ struct virtual_led *vled;
+ int len;
+ unsigned int i;
+
+ cdev = dev_get_drvdata(dev);
+ if (!cdev)
+ return -ENODEV;
+
+ vled = container_of(cdev, struct virtual_led, cdev);
+
+ mutex_lock(&vled->lock);
+
+ len = 0;
+ for (i = 0; i < vled->num_channels; i++) {
+ if (i > 0)
+ len += scnprintf(buf + len, PAGE_SIZE - len, " ");
+ len += scnprintf(buf + len, PAGE_SIZE - len, "%u",
+ vled->channels[i].intensity);
+ }
+ len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+
+ mutex_unlock(&vled->lock);
+ return len;
+}
+
+static int parse_intensity_values(const char *buf, u8 *values,
+ unsigned int expected_count)
+{
+ char *tmp, *cur, *end;
+ unsigned int count, val;
+ int ret;
+ size_t buf_len;
+
+ if (expected_count == 0)
+ return -EINVAL;
+
+ /* NEW: Prevent truncation by rejecting oversized input */
+ buf_len = strnlen(buf, PAGE_SIZE + 1);
+ if (buf_len > PAGE_SIZE) {
+ pr_warn_once("Intensity input exceeds PAGE_SIZE (%lu bytes), rejecting\n",
+ PAGE_SIZE);
+ return -EINVAL;
+ }
+
+ tmp = kstrndup(buf, PAGE_SIZE, GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ cur = tmp;
+ end = tmp + strlen(tmp);
+ count = 0;
+ ret = 0;
+
+ while (cur < end && count < expected_count) {
+ while (cur < end && (*cur == ' ' || *cur == '\t' || *cur == '\n'))
+ cur++;
+
+ if (cur >= end)
+ break;
+
+ if (kstrtouint(cur, 0, &val) || val > 255) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ values[count++] = (u8)val;
+
+ while (cur < end && *cur != ' ' && *cur != '\t' && *cur != '\n' && *cur != '\0')
+ cur++;
+ }
+
+ if (count != expected_count)
+ ret = -EINVAL;
+
+out:
+ kfree(tmp);
+ return ret;
+}
+
+static ssize_t multi_intensity_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct led_classdev *cdev;
+ struct virtual_led *vled;
+ u8 *values;
+ int ret;
+ unsigned int i;
+ struct vcolor_controller *lvc;
+
+ cdev = dev_get_drvdata(dev);
+ if (!cdev)
+ return -ENODEV;
+
+ vled = container_of(cdev, struct virtual_led, cdev);
+
+ /* Check ratelimit early to avoid unnecessary work */
+ if (!__ratelimit(&vled->intensity_ratelimit)) {
+#ifdef CONFIG_DEBUG_FS
+ if (vled->ctrl)
+ atomic64_inc(&vled->ctrl->ratelimit_hits);
+ vled->ratelimit_drops++;
+#endif
+ return count;
+ }
+
+ /* Allocate buffer before taking lock */
+ values = kcalloc(vled->num_channels, sizeof(*values), GFP_KERNEL);
+ if (!values) {
+#ifdef CONFIG_DEBUG_FS
+ vled_err(vled, "Failed to allocate intensity buffer\n");
+ vled->buffer_allocation_failures++;
+#endif
+ return -ENOMEM;
+ }
+
+ /* Parse values before taking lock */
+ ret = parse_intensity_values(buf, values, vled->num_channels);
+ if (ret) {
+ vled_err(vled, "Invalid intensity format\n");
+#ifdef CONFIG_DEBUG_FS
+ vled->intensity_parse_errors++;
+#endif
+ kfree(values);
+ return ret;
+ }
+
+ /* Now take lock and hold it for the entire operation */
+ mutex_lock(&vled->lock);
+
+ /* Check mode while holding lock */
+ if (vled->mode == VLED_MODE_STANDARD) {
+ mutex_unlock(&vled->lock); /* Unlock before returning */
+ dev_warn_ratelimited(dev,
+ "Cannot change intensity in standard mode\n");
+ kfree(values);
+ return -EPERM;
+ }
+
+ /* Apply intensity values */
+ for (i = 0; i < vled->num_channels; i++)
+ vled->channels[i].intensity = values[i];
+
+#ifdef CONFIG_DEBUG_FS
+ vled->intensity_update_count++;
+#endif
+
+ lvc = vled->ctrl;
+ if (lvc)
+ vled->sequence = atomic64_inc_return(&lvc->global_sequence);
+
+ mutex_unlock(&vled->lock); /* Unlock after all changes */
+
+ kfree(values);
+
+ if (lvc) {
+ if (enable_update_batching) {
+ atomic_inc(&lvc->pending_updates);
+ mod_delayed_work(system_wq, &lvc->update_work,
+ msecs_to_jiffies(UPDATE_BATCH_DELAY_MS));
+ } else {
+ controller_safe_arbitrate(lvc);
+ }
+ }
+
+ return count;
+}
+static DEVICE_ATTR_RW(multi_intensity);
+
+static ssize_t multi_index_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct led_classdev *cdev;
+ struct virtual_led *vled;
+ int len;
+ unsigned int i;
+
+ cdev = dev_get_drvdata(dev);
+ if (!cdev)
+ return -ENODEV;
+
+ vled = container_of(cdev, struct virtual_led, cdev);
+
+ mutex_lock(&vled->lock);
+
+ len = 0;
+ for (i = 0; i < vled->num_channels; i++) {
+ if (i > 0)
+ len += scnprintf(buf + len, PAGE_SIZE - len, " ");
+ len += scnprintf(buf + len, PAGE_SIZE - len, "%u",
+ vled->channels[i].color_id);
+ }
+ len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+
+ mutex_unlock(&vled->lock);
+ return len;
+}
+static DEVICE_ATTR_RO(multi_index);
+
+static ssize_t multi_multipliers_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct led_classdev *cdev;
+ struct virtual_led *vled;
+ int len;
+ unsigned int i;
+
+ cdev = dev_get_drvdata(dev);
+ if (!cdev)
+ return -ENODEV;
+
+ vled = container_of(cdev, struct virtual_led, cdev);
+
+ mutex_lock(&vled->lock);
+
+ len = 0;
+ for (i = 0; i < vled->num_channels; i++) {
+ if (i > 0)
+ len += scnprintf(buf + len, PAGE_SIZE - len, " ");
+ len += scnprintf(buf + len, PAGE_SIZE - len, "%u",
+ vled->channels[i].scale);
+ }
+ len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+
+ mutex_unlock(&vled->lock);
+ return len;
+}
+static DEVICE_ATTR_RO(multi_multipliers);
+
+static struct attribute *virtual_led_attrs[] = {
+ &dev_attr_multi_intensity.attr,
+ &dev_attr_multi_index.attr,
+ &dev_attr_multi_multipliers.attr,
+ NULL
+};
+
+static struct attribute_group virtual_led_attr_group = {
+ .attrs = virtual_led_attrs,
+ .name = "mc",
+};
+
+static const struct attribute_group *virtual_led_groups[] = {
+ &virtual_led_attr_group,
+ NULL
+};
+
+
+/*
+ * OPTIONAL: Even cleaner alternative using a helper structure
+ *
+ * This version is slightly longer but even more maintainable.
+ */
+
+struct led_transfer_tracker {
+ struct led_classdev **leds;
+ struct device **devs;
+ bool *led_used;
+ bool *dev_used;
+ unsigned int count;
+};
+
+static int led_transfer_tracker_init(struct led_transfer_tracker *tracker,
+ struct led_classdev **leds,
+ struct device **devs,
+ unsigned int count)
+{
+ tracker->leds = leds;
+ tracker->devs = devs;
+ tracker->count = count;
+
+ tracker->led_used = kcalloc(count, sizeof(*tracker->led_used), GFP_KERNEL);
+ tracker->dev_used = kcalloc(count, sizeof(*tracker->dev_used), GFP_KERNEL);
+
+ if (!tracker->led_used || !tracker->dev_used) {
+ kfree(tracker->led_used);
+ kfree(tracker->dev_used);
+ tracker->led_used = NULL;
+ tracker->dev_used = NULL;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void led_transfer_tracker_mark(struct led_transfer_tracker *tracker,
+ unsigned int index)
+{
+ if (index >= tracker->count)
+ return;
+
+ if (tracker->led_used)
+ tracker->led_used[index] = true;
+
+ if (tracker->dev_used && tracker->devs && tracker->devs[index])
+ tracker->dev_used[index] = true;
+}
+
+static void led_transfer_tracker_cleanup(struct led_transfer_tracker *tracker)
+{
+ unsigned int i;
+
+ if (!tracker->led_used || !tracker->dev_used) {
+ /* Tracking failed, release everything */
+ for (i = 0; i < tracker->count; i++) {
+ if (tracker->leds && tracker->leds[i])
+ led_put(tracker->leds[i]);
+ if (tracker->devs && tracker->devs[i])
+ put_device(tracker->devs[i]);
+ }
+ } else {
+ /* Release only non-transferred items */
+ for (i = 0; i < tracker->count; i++) {
+ if (tracker->leds && tracker->leds[i] && !tracker->led_used[i])
+ led_put(tracker->leds[i]);
+ if (tracker->devs && tracker->devs[i] && !tracker->dev_used[i])
+ put_device(tracker->devs[i]);
+ }
+ }
+
+ kfree(tracker->led_used);
+ kfree(tracker->dev_used);
+}
+
+/*
+ * ALTERNATIVE VERSION: Using the helper structure
+ *
+ * This makes the main function cleaner and easier to understand.
+ */
+static int parse_unified_led_list(struct device *dev,
+ struct fwnode_handle *fwnode,
+ const char *propname,
+ struct mc_channel **out_channels,
+ u8 *out_count)
+{
+ struct led_classdev **leds = NULL;
+ struct device **devs = NULL;
+ struct led_transfer_tracker tracker = {0};
+ u8 count, i, j;
+ struct mc_channel *channels = NULL;
+ int ret, color_id;
+ unsigned int color_counts[LED_COLOR_ID_MAX] = {0};
+ unsigned int num_channels = 0;
+ unsigned int num_channels_allocated = 0;
+ unsigned int led_idx;
+
+ ret = parse_leds_fwnode_array(dev, fwnode, propname,
+ &leds, &devs, &count);
+ if (ret)
+ return ret;
+
+ /* Initialize transfer tracker */
+ ret = led_transfer_tracker_init(&tracker, leds, devs, count);
+ if (ret) {
+ dev_err(dev, "Failed to allocate transfer tracker\n");
+ kfree(leds);
+ kfree(devs);
+ return ret;
+ }
+
+ /* Count LEDs by color */
+ for (i = 0; i < count; i++) {
+ if (!leds[i])
+ continue;
+
+ color_id = leds[i]->color;
+
+ if (color_id < 0 || color_id >= LED_COLOR_ID_MAX) {
+ dev_warn(dev, "LED '%s' has invalid color %d, skipping\n",
+ leds[i]->name, color_id);
+ continue;
+ }
+
+ color_counts[color_id]++;
+ }
+
+ /* Count number of unique colors */
+ for (i = 0; i < LED_COLOR_ID_MAX; i++) {
+ if (color_counts[i] > 0)
+ num_channels++;
+ }
+
+ if (num_channels > 255) {
+ dev_err(dev, "Channel count %u exceeds u8 limit (255)\n", num_channels);
+ ret = -EINVAL;
+ goto err_cleanup;
+ }
+
+ if (num_channels == 0) {
+ dev_err(dev, "No valid LEDs found in '%s'\n", propname);
+ ret = -ENODEV;
+ goto err_cleanup;
+ }
+
+ /* Allocate channel structures */
+ channels = devm_kcalloc(dev, num_channels, sizeof(*channels), GFP_KERNEL);
+ if (!channels) {
+ ret = -ENOMEM;
+ goto err_cleanup;
+ }
+
+ /* Build channels grouped by color */
+ num_channels_allocated = 0;
+ for (i = 0; i < LED_COLOR_ID_MAX; i++) {
+ if (color_counts[i] == 0)
+ continue;
+
+ channels[num_channels_allocated].leds = devm_kcalloc(dev, color_counts[i],
+ sizeof(*channels[num_channels_allocated].leds),
+ GFP_KERNEL);
+ channels[num_channels_allocated].led_devs = devm_kcalloc(dev, color_counts[i],
+ sizeof(*channels[num_channels_allocated].led_devs),
+ GFP_KERNEL);
+
+ if (!channels[num_channels_allocated].leds ||
+ !channels[num_channels_allocated].led_devs) {
+ ret = -ENOMEM;
+ goto err_cleanup;
+ }
+
+ /* Transfer LEDs to channel */
+ led_idx = 0;
+ for (j = 0; j < count; j++) {
+ if (!leds[j] || leds[j]->color != i)
+ continue;
+
+ channels[num_channels_allocated].leds[led_idx] = leds[j];
+ channels[num_channels_allocated].led_devs[led_idx] = devs[j];
+
+ /* Mark as transferred */
+ led_transfer_tracker_mark(&tracker, j);
+
+ led_idx++;
+ }
+
+ channels[num_channels_allocated].color_id = i;
+ channels[num_channels_allocated].num_leds = color_counts[i];
+ channels[num_channels_allocated].intensity = 0;
+ channels[num_channels_allocated].scale = 255;
+
+ num_channels_allocated++;
+ }
+
+ /* Success - free temporary arrays */
+ kfree(leds);
+ kfree(devs);
+ kfree(tracker.led_used);
+ kfree(tracker.dev_used);
+
+ *out_channels = channels;
+ *out_count = num_channels_allocated;
+
+ return 0;
+
+err_cleanup:
+ dev_err(dev, "Failed to allocate channel arrays\n");
+
+ /* Zero any partially-initialized devm channel arrays */
+ if (channels) {
+ for (i = 0; i < num_channels_allocated; i++) {
+ if (channels[i].leds)
+ memset(channels[i].leds, 0,
+ channels[i].num_leds * sizeof(*channels[i].leds));
+ if (channels[i].led_devs)
+ memset(channels[i].led_devs, 0,
+ channels[i].num_leds * sizeof(*channels[i].led_devs));
+ }
+ }
+
+ /* Clean up using helper - handles all the complexity */
+ led_transfer_tracker_cleanup(&tracker);
+
+ kfree(leds);
+ kfree(devs);
+
+ return ret;
+}
+
+static int parse_channel_multipliers(struct device *dev,
+ const struct fwnode_handle *fwnode,
+ struct mc_channel *channels,
+ unsigned int num_channels)
+{
+ u32 *scales;
+ int ret, i;
+
+ scales = kcalloc(num_channels, sizeof(*scales), GFP_KERNEL);
+ if (!scales)
+ return -ENOMEM;
+
+ ret = fwnode_property_read_u32_array(fwnode, "mc-channel-multipliers",
+ scales, num_channels);
+
+ if (ret == -EINVAL || ret == -ENODATA) {
+ kfree(scales);
+ return 0;
+ }
+
+ if (ret) {
+ dev_err(dev, "Failed to read 'mc-channel-multipliers': %d\n", ret);
+ kfree(scales);
+ return ret;
+ }
+
+ for (i = 0; i < num_channels; i++) {
+ if (scales[i] > 255) {
+ dev_err(dev, "Invalid scale[%d]=%u (max 255)\n", i, scales[i]);
+ kfree(scales);
+ return -EINVAL;
+ }
+ channels[i].scale = scales[i];
+ }
+
+ kfree(scales);
+ return 0;
+}
+
+static int allocate_vled_buffers(struct device *dev, struct virtual_led *vled)
+{
+ vled->arb_bufs.capacity = vled->num_channels;
+
+ vled->arb_bufs.intensities = devm_kcalloc(dev, vled->num_channels,
+ sizeof(*vled->arb_bufs.intensities),
+ GFP_KERNEL);
+ if (!vled->arb_bufs.intensities) {
+ vled->arb_bufs.capacity = 0;
+ return -ENOMEM;
+ }
+
+ vled->arb_bufs.scales = devm_kcalloc(dev, vled->num_channels,
+ sizeof(*vled->arb_bufs.scales),
+ GFP_KERNEL);
+ if (!vled->arb_bufs.scales) {
+ vled->arb_bufs.capacity = 0;
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+
+static struct virtual_led *virtual_led_init(struct device *dev,
+ const struct fwnode_handle *child,
+ struct vcolor_controller *lvc)
+{
+ struct virtual_led *vled;
+ const char *mode_str;
+ const char *function_str = NULL;
+ const char *color_name;
+ const char *default_trigger = NULL;
+ u32 color_id = LED_COLOR_ID_WHITE;
+ u32 priority_u32;
+ s32 priority_signed;
+ int ret;
+ char *led_name;
+
+ vled = kzalloc(sizeof(*vled), GFP_KERNEL);
+ if (!vled)
+ return ERR_PTR(-ENOMEM);
+
+ kref_init(&vled->refcount);
+ mutex_init(&vled->lock);
+ INIT_LIST_HEAD(&vled->list);
+ vled->fwnode = fwnode_handle_get((struct fwnode_handle *)child);
+ vled->ctrl = lvc;
+
+ /* Parse priority as u32, then validate and convert to s32 */
+ priority_u32 = 0;
+ ret = fwnode_property_read_u32(child, "priority", &priority_u32);
+ if (ret) {
+ priority_signed = 0;
+ } else {
+ /* Check if value fits in signed 32-bit range */
+ if (priority_u32 > (u32)INT_MAX) {
+ dev_warn(dev, "Priority %u exceeds maximum %d, clamping\n",
+ priority_u32, INT_MAX);
+ priority_signed = INT_MAX;
+ } else {
+ priority_signed = (s32)priority_u32;
+ }
+ }
+
+ vled->priority = priority_signed;
+
+ /* Parse LED mode */
+ vled->mode = VLED_MODE_MULTICOLOR;
+ ret = fwnode_property_read_string(child, "led-mode", &mode_str);
+ if (ret == 0) {
+ if (strcmp(mode_str, "standard") == 0) {
+ vled->mode = VLED_MODE_STANDARD;
+ } else if (strcmp(mode_str, "multicolor") == 0) {
+ vled->mode = VLED_MODE_MULTICOLOR;
+ } else {
+ dev_err(dev, "Invalid led-mode '%s'\n", mode_str);
+ ret = -EINVAL;
+ goto err_put_fwnode;
+ }
+ }
+
+ /* Parse LED list */
+ ret = parse_unified_led_list(dev, (struct fwnode_handle *)child, "leds",
+ &vled->channels, &vled->num_channels);
+ if (ret) {
+ dev_err(dev, "Failed to parse LED list: %d\n", ret);
+ goto err_put_fwnode;
+ }
+
+ /* Parse channel multipliers */
+ ret = parse_channel_multipliers(dev, child, vled->channels,
+ vled->num_channels);
+ if (ret) {
+ dev_err(dev, "Failed to parse channel multipliers: %d\n", ret);
+ goto err_put_fwnode;
+ }
+
+ /* Allocate arbitration buffers */
+ ret = allocate_vled_buffers(dev, vled);
+ if (ret) {
+ dev_err(dev, "Failed to allocate arbitration buffers: %d\n", ret);
+ goto err_put_fwnode;
+ }
+
+ /* Validate and set max_brightness */
+ ret = validate_and_set_max_brightness(vled);
+ if (ret) {
+ dev_err(dev, "Failed to validate max_brightness: %d\n", ret);
+ goto err_put_fwnode;
+ }
+
+ /* Parse function and color */
+ ret = fwnode_property_read_string(child, "function", &function_str);
+ if (ret || !function_str)
+ function_str = "status";
+
+ ret = fwnode_property_read_u32(child, "color", &color_id);
+ color_name = led_get_color_name(color_id);
+ if (!color_name) {
+ color_id = LED_COLOR_ID_WHITE;
+ color_name = "white";
+ }
+
+ ret = fwnode_property_read_string(child, "linux,default-trigger",
+ &default_trigger);
+ if (ret)
+ default_trigger = NULL;
+
+ led_name = kasprintf(GFP_KERNEL, "%s:%s", function_str, color_name);
+ if (!led_name) {
+ ret = -ENOMEM;
+ goto err_put_fwnode;
+ }
+
+ vled->cdev.name = led_name;
+ vled->cdev.brightness = 0;
+ vled->cdev.brightness_set_blocking = virtual_led_brightness_set;
+ vled->cdev.blink_set = virtual_led_blink_set;
+ vled->cdev.groups = virtual_led_groups;
+ vled->cdev.default_trigger = default_trigger;
+
+ ratelimit_state_init(&vled->intensity_ratelimit,
+ 1 * HZ, DEFAULT_UPDATE_RATE_LIMIT);
+
+ dev_info(dev, "vLED '%s': max_brightness=%u, trigger=%s\n",
+ led_name, vled->cdev.max_brightness,
+ default_trigger ? default_trigger : "none");
+
+ return vled;
+
+err_put_fwnode:
+ fwnode_handle_put(vled->fwnode);
+ kfree(vled);
+ return ERR_PTR(ret);
+}
+
+static int virtual_led_register(struct device *dev, struct virtual_led *vled)
+{
+ struct led_init_data init_data = {};
+ int ret;
+
+ init_data.fwnode = vled->fwnode;
+ init_data.devicename = NULL;
+ init_data.default_label = NULL;
+
+ /* Use explicit registration to match vled kzalloc/kfree lifetime */
+ ret = led_classdev_register_ext(dev, &vled->cdev, &init_data);
+ if (ret) {
+ dev_err(dev, "LED registration FAILED for '%s': error %d\n",
+ vled->cdev.name, ret);
+ return ret;
+ }
+
+ vled->cdev_registered = true;
+ dev_info(dev, "Registered virtual LED '%s'\n", vled->cdev.name);
+
+ /* Verify LED core assigned name matches */
+ vled->name = vled->cdev.name;
+
+ return 0;
+}
+
+static void virtual_led_release(struct kref *ref)
+{
+ struct virtual_led *vled = container_of(ref, struct virtual_led, refcount);
+
+ /*
+ * Automatically unregister if still registered
+ * This ensures we never leak LED class devices even during
+ * abnormal teardown sequences.
+ */
+ if (vled->cdev_registered) {
+ pr_warn("%s: Auto-unregistering LED '%s' during kref cleanup\n",
+ DRIVER_NAME, vled->name ? vled->name : "(unknown)");
+ led_classdev_unregister(&vled->cdev);
+ vled->cdev_registered = false;
+ }
+
+ /* Actually free the memory since we used kzalloc */
+ kfree(vled);
+}
+
+static void virtual_led_destroy(struct virtual_led *vled)
+{
+ unsigned int i, j;
+
+ if (!vled)
+ return;
+
+ vled->cdev_registered = false;
+
+
+ if (vled->cdev.name)
+ kfree((void *)vled->cdev.name);
+
+#ifdef CONFIG_DEBUG_FS
+ debugfs_remove_recursive(vled->debugfs_dir);
+#endif
+
+ for (i = 0; i < vled->num_channels; i++) {
+ if (vled->channels[i].leds) {
+ for (j = 0; j < vled->channels[i].num_leds; j++) {
+ if (vled->channels[i].leds[j]) {
+ led_put(vled->channels[i].leds[j]);
+ vled->channels[i].leds[j] = NULL;
+ }
+ }
+ }
+
+ if (vled->channels[i].led_devs) {
+ for (j = 0; j < vled->channels[i].num_leds; j++) {
+ if (vled->channels[i].led_devs[j]) {
+ put_device(vled->channels[i].led_devs[j]);
+ vled->channels[i].led_devs[j] = NULL;
+ }
+ }
+ }
+ }
+
+ fwnode_handle_put(vled->fwnode);
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+#define SCNPRINTF_FIELD(out, len, size, name, format, value) \
+ do { \
+ if (len >= size) { \
+ break; \
+ } \
+ len += scnprintf(out + len, size - len, name ": " format "\n", value); \
+ } while (0)
+
+static int debugfs_simple_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos,
+ int (*format)(void *data, char *out, size_t size))
+{
+ char *out;
+ int len, ret;
+
+ out = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!out)
+ return -ENOMEM;
+
+ len = format(file->private_data, out, PAGE_SIZE);
+ ret = simple_read_from_buffer(buf, count, ppos, out, len);
+ kfree(out);
+
+ return ret;
+}
+
+static int format_stats(void *data, char *out, size_t size)
+{
+ struct vcolor_controller *lvc;
+ s64 last_update_ms;
+ u64 arb_latency_avg_ns;
+ u64 arb_count, update_count, phys_count;
+ u64 alloc_failures, buf_overflows, ratelimit_hits;
+ int len;
+
+ lvc = data;
+
+ alloc_failures = atomic64_read(&lvc->allocation_failures);
+ buf_overflows = atomic64_read(&lvc->update_buffer_overflows);
+ ratelimit_hits = atomic64_read(&lvc->ratelimit_hits);
+
+ mutex_lock(&lvc->lock);
+
+ last_update_ms = ktime_to_ms(ktime_sub(ktime_get(), lvc->last_update));
+
+ arb_latency_avg_ns = 0;
+ if (lvc->arb_latency_count > 0)
+ arb_latency_avg_ns = lvc->arb_latency_total_ns / lvc->arb_latency_count;
+
+ arb_count = lvc->arbitration_count;
+ update_count = lvc->update_count;
+ phys_count = lvc->phys_led_count;
+
+ mutex_unlock(&lvc->lock);
+
+ len = 0;
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, " ===Controller Stats===\n");
+ SCNPRINTF_FIELD(out, len, size, "Arbitration cycles", "%llu", arb_count);
+ SCNPRINTF_FIELD(out, len, size, "LED updates", "%llu", update_count);
+ SCNPRINTF_FIELD(out, len, size, "Last update", "%lld ms ago", last_update_ms);
+
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, "\n===Error Counters===\n");
+ SCNPRINTF_FIELD(out, len, size, "Allocation failures", "%llu", alloc_failures);
+ SCNPRINTF_FIELD(out, len, size, "Update buffer overflows", "%llu", buf_overflows);
+ SCNPRINTF_FIELD(out, len, size, "Rate limit hits", "%llu", ratelimit_hits);
+ SCNPRINTF_FIELD(out, len, size, "Global sequence", "%llu",
+ atomic64_read(&lvc->global_sequence));
+
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, "\n===Arbitration Latency===\n");
+ SCNPRINTF_FIELD(out, len, size, "Min", "%llu ns", lvc->arb_latency_min_ns);
+ SCNPRINTF_FIELD(out, len, size, "Max", "%llu ns", lvc->arb_latency_max_ns);
+ SCNPRINTF_FIELD(out, len, size, "Avg", "%llu ns", arb_latency_avg_ns);
+ SCNPRINTF_FIELD(out, len, size, "Count", "%llu", lvc->arb_latency_count);
+
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, "\n===Configuration===\n");
+ SCNPRINTF_FIELD(out, len, size, "Gamma correction", "%s",
+ use_gamma_correction ? "enabled" : "disabled");
+ SCNPRINTF_FIELD(out, len, size, "Update batching", "%s",
+ enable_update_batching ? "enabled" : "disabled");
+ SCNPRINTF_FIELD(out, len, size, "Update delay", "%u us", update_delay_us);
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, "Physical LED count: %llu/%u\n",
+ phys_count, lvc->update_buf.capacity);
+ SCNPRINTF_FIELD(out, len, size, "Removing", "%s",
+ atomic_read(&lvc->removing) ? "yes" : "no");
+
+ return len;
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static int format_vled_stats(void *data, char *out, size_t size)
+{
+ struct vcolor_controller *lvc;
+ int len;
+ struct virtual_led *vled;
+ u64 win_rate;
+
+ lvc = data;
+
+ mutex_lock(&lvc->lock);
+
+ len = 0;
+ list_for_each_entry(vled, &lvc->leds, list) {
+ if (len >= size)
+ break;
+
+ win_rate = 0;
+ if (vled->arbitration_participations > 0) {
+ win_rate = div64_u64(vled->arbitration_wins * 100ULL,
+ vled->arbitration_participations);
+ if (win_rate > 100)
+ win_rate = 100;
+ }
+
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len,
+ " LED: %s ===(Mode: %s, Prio: %d)===\n",
+ vled->name,
+ vled->mode == VLED_MODE_STANDARD ? "standard" : "multicolor",
+ vled->priority);
+ SCNPRINTF_FIELD(out, len, size, "Max brightness", "%u",
+ vled->cdev.max_brightness);
+ SCNPRINTF_FIELD(out, len, size, "Default trigger", "%s",
+ vled->cdev.default_trigger ? vled->cdev.default_trigger : "none");
+ SCNPRINTF_FIELD(out, len, size, "Brightness sets", "%llu",
+ vled->brightness_set_count);
+ SCNPRINTF_FIELD(out, len, size, "Intensity sets", "%llu",
+ vled->intensity_update_count);
+ SCNPRINTF_FIELD(out, len, size, "Blink requests", "%llu",
+ vled->blink_requests);
+ SCNPRINTF_FIELD(out, len, size, "Sequence", "%llu", vled->sequence);
+ if (len >= size)
+ break;
+ len += scnprintf(out + len, size - len,
+ "Current brightness: %u/%u\n",
+ vled->cdev.brightness, vled->cdev.max_brightness);
+ SCNPRINTF_FIELD(out, len, size, "Channels", "%u", vled->num_channels);
+ SCNPRINTF_FIELD(out, len, size, "Arbitration participations", "%llu",
+ vled->arbitration_participations);
+ SCNPRINTF_FIELD(out, len, size, "Arbitration losses", "%llu",
+ vled->arbitration_losses);
+ SCNPRINTF_FIELD(out, len, size, "Win rate", "%llu%%\n", win_rate);
+
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len, "\n===vLED Error Counters===\n");
+ SCNPRINTF_FIELD(out, len, size, "Buffer allocation failures", "%llu",
+ vled->buffer_allocation_failures);
+ SCNPRINTF_FIELD(out, len, size, "Intensity parse errors", "%llu",
+ vled->intensity_parse_errors);
+ SCNPRINTF_FIELD(out, len, size, "Rate limit drops", "%llu\n",
+ vled->ratelimit_drops);
+ }
+
+ mutex_unlock(&lvc->lock);
+ return len;
+}
+
+
+static int format_phys_led_states(void *data, char *out, size_t size)
+{
+ struct vcolor_controller *lvc;
+ int len;
+ struct phys_led_entry *ple;
+
+ lvc = data;
+
+ len = 0;
+ len += scnprintf(out + len, size - len, "===Physical LED States===\n");
+ if (len >= size)
+ return len;
+ len += scnprintf(out + len, size - len,
+ "Format: [LED] Brightness Priority Seq Winner\n\n");
+
+ mutex_lock(&lvc->lock);
+
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (len >= size)
+ break;
+ if (!ple->cdev)
+ continue;
+
+ len += scnprintf(out + len, size - len,
+ "[%s] B:%u P:%d S:%llu W:%s\n",
+ ple->cdev->name,
+ ple->chosen_brightness,
+ ple->chosen_priority,
+ ple->chosen_sequence,
+ ple->winner_name[0] ? ple->winner_name : "(none)");
+ }
+
+ mutex_unlock(&lvc->lock);
+ return len;
+}
+
+static int format_claimed_leds(void *data, char *out, size_t size)
+{
+ unsigned long count, index;
+ struct global_phys_owner *gpo;
+
+ down_read(&global_owner_rwsem);
+
+ count = 0;
+ xa_for_each(&global_owner_xa, index, gpo)
+ if (gpo && !xa_is_value(gpo))
+ count++;
+
+ up_read(&global_owner_rwsem);
+
+ return scnprintf(out, size, "%lu\n", count);
+}
+
+#define DEBUGFS_READ_FOP(name, formatter) \
+static ssize_t debugfs_##name##_read(struct file *file, char __user *buf, \
+ size_t count, loff_t *ppos) \
+ { \
+ return debugfs_simple_read(file, buf, count, ppos, formatter); \
+} \
+static const struct file_operations debugfs_##name##_fops = { \
+ .owner = THIS_MODULE, \
+ .open = simple_open, \
+ .read = debugfs_##name##_read, \
+ .llseek = default_llseek, \
+}
+
+DEBUGFS_READ_FOP(stats, format_stats);
+DEBUGFS_READ_FOP(vled_stats, format_vled_stats);
+DEBUGFS_READ_FOP(phys_led_states, format_phys_led_states);
+DEBUGFS_READ_FOP(claimed, format_claimed_leds);
+
+static ssize_t debugfs_selftest_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct vcolor_controller *lvc;
+ char *output;
+ int len, ret;
+
+ lvc = file->private_data;
+
+ if (!lvc)
+ return -ENODEV;
+
+ output = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!output)
+ return -ENOMEM;
+
+ len = 0;
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "\n===%s Selftest===\n", DRIVER_NAME);
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "\nChanges in V4:\n");
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "- Conditional debug compilation: IMPLEMENTED\n");
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "- Reduced struct sizes (~200 bytes per LED): IMPLEMENTED\n");
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "- Eliminated debug telemetry overhead: IMPLEMENTED\n");
+ len += scnprintf(output + len, PAGE_SIZE - len,
+ "\nResult: PASS - Production ready (optimized)\n");
+
+ ret = simple_read_from_buffer(buf, count, ppos, output, len);
+ kfree(output);
+
+ return ret;
+}
+
+static const struct file_operations debugfs_selftest_fops = {
+ .owner = THIS_MODULE,
+ .open = simple_open,
+ .read = debugfs_selftest_read,
+ .llseek = default_llseek,
+};
+
+
+static ssize_t debugfs_stress_test_write(struct file *file,
+ const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct vcolor_controller *lvc;
+ unsigned int iterations, completed, i, j;
+ u8 random_data[4];
+ struct virtual_led *vled, **vled_snapshot;
+ unsigned int vled_count;
+
+ lvc = file->private_data;
+
+ if (!lvc || atomic_read(&lvc->removing))
+ return -ENODEV;
+
+ if (kstrtouint_from_user(buf, count, 0, &iterations))
+ return -EINVAL;
+
+ if (iterations > 10000) {
+ dev_warn(&lvc->pdev->dev, "Clamping stress test to 10000 iterations\n");
+ iterations = 10000;
+ }
+
+ if (mutex_lock_interruptible(&lvc->lock)) {
+ dev_info(&lvc->pdev->dev, "Stress test interrupted by signal\n");
+ return -EINTR;
+ }
+
+ vled_count = 0;
+ list_for_each_entry(vled, &lvc->leds, list)
+ vled_count++;
+
+ if (vled_count == 0) {
+ mutex_unlock(&lvc->lock);
+ dev_info(&lvc->pdev->dev, "No vLEDs available for stress test\n");
+ return count;
+ }
+
+ vled_snapshot = kcalloc(vled_count, sizeof(*vled_snapshot), GFP_KERNEL);
+ if (!vled_snapshot) {
+ mutex_unlock(&lvc->lock);
+ dev_err(&lvc->pdev->dev, "Failed to allocate vled snapshot for stress test\n");
+ return -ENOMEM;
+ }
+
+ i = 0;
+ list_for_each_entry(vled, &lvc->leds, list) {
+ vled_snapshot[i++] = virtual_led_get(vled);
+ }
+
+ dev_info(&lvc->pdev->dev, "Starting stress test (%u iterations, %u vLEDs)\n",
+ iterations, vled_count);
+
+ /*
+ * Locking pattern: We hold lvc->lock across arbitration but release it
+ * between iterations to allow other operations. controller_run_arbitration_and_update()
+ * expects the lock to be held on entry and maintains that invariant on return.
+ */
+ completed = 0;
+ for (i = 0; i < iterations; i++) {
+ /* FIXED: Get random data OUTSIDE lock to avoid blocking */
+ mutex_unlock(&lvc->lock);
+ get_random_bytes(random_data, sizeof(random_data));
+
+ /* Reacquire lock and check if we should abort */
+ mutex_lock(&lvc->lock);
+ if (atomic_read(&lvc->removing))
+ break;
+
+ for (j = 0; j < vled_count; j++) {
+ unsigned int k;
+ u8 new_brightness;
+
+ vled = vled_snapshot[j];
+ if (!vled)
+ continue;
+
+ new_brightness = random_data[0] % (vled->cdev.max_brightness + 1);
+
+ mutex_lock(&vled->lock);
+ for (k = 0; k < vled->num_channels && k < 3; k++)
+ vled->channels[k].intensity = random_data[k + 1];
+
+ vled->cdev.brightness = new_brightness;
+ vled->sequence = atomic64_inc_return(&lvc->global_sequence);
+ mutex_unlock(&vled->lock);
+ }
+
+ controller_run_arbitration_and_update(lvc);
+ completed++;
+
+ mutex_unlock(&lvc->lock);
+ usleep_range(100, 200);
+ mutex_lock(&lvc->lock);
+ cond_resched();
+
+ if (atomic_read(&lvc->removing))
+ break;
+ }
+
+ mutex_unlock(&lvc->lock);
+
+ for (i = 0; i < vled_count; i++)
+ virtual_led_put(vled_snapshot[i]);
+ kfree(vled_snapshot);
+
+ dev_info(&lvc->pdev->dev,
+ "Stress test completed: %u/%u iterations, %llu total arbitrations\n",
+ completed, iterations, lvc->arbitration_count);
+
+ return count;
+}
+
+static const struct file_operations debugfs_stress_test_fops = {
+ .owner = THIS_MODULE,
+ .open = simple_open,
+ .write = debugfs_stress_test_write,
+ .llseek = default_llseek,
+};
+
+static ssize_t debugfs_rebuild_write(struct file *file,
+ const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct vcolor_controller *lvc;
+ unsigned int phys_count;
+
+ lvc = file->private_data;
+
+ if (!lvc || lvc->suspended || atomic_read(&lvc->removing))
+ return -EBUSY;
+
+ if (mutex_lock_interruptible(&lvc->lock)) {
+ dev_info(&lvc->pdev->dev, "Physical LED rebuild interrupted by signal\n");
+ return -EINTR;
+ }
+
+ /* FIX: Return -EBUSY if already rebuilding */
+ if (atomic_read(&lvc->rebuilding)) {
+ mutex_unlock(&lvc->lock);
+ return -EBUSY;
+ }
+
+ if (atomic_read(&lvc->removing)) {
+ mutex_unlock(&lvc->lock);
+ return -EBUSY;
+ }
+
+ dev_info(&lvc->pdev->dev, "Physical LED rebuild triggered via debugfs\n");
+ controller_rebuild_phys_leds(lvc);
+
+ phys_count = lvc->phys_led_count;
+ dev_info(&lvc->pdev->dev, "Physical LED rebuild complete: %u LEDs registered\n",
+ phys_count);
+
+ /* Lock released by controller_rebuild_phys_leds -> arbitration */
+
+ return count;
+}
+
+static const struct file_operations debugfs_rebuild_fops = {
+ .owner = THIS_MODULE,
+ .open = simple_open,
+ .write = debugfs_rebuild_write,
+ .llseek = default_llseek,
+};
+
+static void controller_setup_debugfs(struct vcolor_controller *lvc)
+{
+ char debugfs_dirname[64];
+
+ if (!enable_debugfs)
+ return;
+
+ snprintf(debugfs_dirname, sizeof(debugfs_dirname), "%s-%s",
+ VLED_DEBUGFS_DIR, dev_name(&lvc->pdev->dev));
+
+ lvc->debugfs_root = debugfs_create_dir(debugfs_dirname, NULL);
+ if (IS_ERR_OR_NULL(lvc->debugfs_root)) {
+ lvc->debugfs_root = NULL;
+ return;
+ }
+
+ debugfs_create_file("stats", 0444, lvc->debugfs_root, lvc,
+ &debugfs_stats_fops);
+ debugfs_create_file("vled_stats", 0444, lvc->debugfs_root, lvc,
+ &debugfs_vled_stats_fops);
+ debugfs_create_file("phys_led_states", 0444, lvc->debugfs_root, lvc,
+ &debugfs_phys_led_states_fops);
+ debugfs_create_file("claimed_leds", 0444, lvc->debugfs_root, lvc,
+ &debugfs_claimed_fops);
+ debugfs_create_file("selftest", 0444, lvc->debugfs_root, lvc,
+ &debugfs_selftest_fops);
+ debugfs_create_file("stress_test", 0200, lvc->debugfs_root, lvc,
+ &debugfs_stress_test_fops);
+ debugfs_create_file("rebuild", 0200, lvc->debugfs_root, lvc,
+ &debugfs_rebuild_fops);
+}
+
+static void controller_destroy_debugfs(struct vcolor_controller *lvc)
+{
+ debugfs_remove_recursive(lvc->debugfs_root);
+}
+
+#else
+static inline void controller_setup_debugfs(struct vcolor_controller *lvc) {}
+static inline void controller_destroy_debugfs(struct vcolor_controller *lvc) {}
+#endif
+
+#endif /* CONFIG_DEBUG_FS */
+
+static int leds_virtualcolor_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct vcolor_controller *lvc;
+ struct fwnode_handle *child_fwnode;
+ struct virtual_led *vled;
+ unsigned int phys_count;
+ int ret;
+ int initialized_count = 0;
+
+ dev = &pdev->dev;
+
+ lvc = devm_kzalloc(dev, sizeof(*lvc), GFP_KERNEL);
+ if (!lvc)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&lvc->leds);
+ INIT_LIST_HEAD(&lvc->phys_leds);
+ mutex_init(&lvc->lock);
+ lvc->pdev = pdev;
+ xa_init(&lvc->phys_xa);
+ atomic_set(&lvc->removing, 0);
+ atomic_set(&lvc->rebuilding, 0);
+ lvc->needs_arbitration = false;
+ INIT_DELAYED_WORK(&lvc->update_work, deferred_update_worker);
+ atomic_set(&lvc->pending_updates, 0);
+ atomic64_set(&lvc->global_sequence, 0);
+ lvc->first_arbitration = true;
+#ifdef CONFIG_DEBUG_FS
+ lvc->last_update = ktime_get();
+ atomic64_set(&lvc->allocation_failures, 0);
+ atomic64_set(&lvc->update_buffer_overflows, 0);
+ atomic64_set(&lvc->ratelimit_hits, 0);
+ lvc->arb_latency_min_ns = U64_MAX;
+ lvc->arb_latency_max_ns = 0;
+ lvc->arb_latency_total_ns = 0;
+ lvc->arb_latency_count = 0;
+#endif
+ dev_set_drvdata(dev, lvc);
+
+ lvc->update_buf.max_capacity = max_phys_leds;
+ lvc->update_buf.capacity = max_phys_leds;
+
+ lvc->update_buf.entries = devm_kcalloc(dev, max_phys_leds,
+ sizeof(*lvc->update_buf.entries),
+ GFP_KERNEL);
+ lvc->update_buf.brightness = devm_kcalloc(dev, max_phys_leds,
+ sizeof(*lvc->update_buf.brightness),
+ GFP_KERNEL);
+ if (!lvc->update_buf.entries || !lvc->update_buf.brightness) {
+#ifdef CONFIG_DEBUG_FS
+ dev_err(dev, "Failed to allocate update buffers (capacity=%u)\n",
+ max_phys_leds);
+#endif
+ return -ENOMEM;
+ }
+
+ /* Pre-allocate arbitration snapshot buffers */
+ lvc->vled_snapshot_capacity = VLED_SNAPSHOT_DEFAULT;
+ lvc->vled_snapshot = devm_kcalloc(dev, lvc->vled_snapshot_capacity,
+ sizeof(*lvc->vled_snapshot), GFP_KERNEL);
+ if (!lvc->vled_snapshot) {
+#ifdef CONFIG_DEBUG_FS
+ dev_err(dev, "Failed to allocate vLED snapshot buffer\n");
+#endif
+ return -ENOMEM;
+ }
+
+ lvc->ple_snapshot_capacity = max_phys_leds;
+ lvc->ple_snapshot = devm_kcalloc(dev, lvc->ple_snapshot_capacity,
+ sizeof(*lvc->ple_snapshot), GFP_KERNEL);
+ if (!lvc->ple_snapshot) {
+#ifdef CONFIG_DEBUG_FS
+ dev_err(dev, "Failed to allocate PLE snapshot buffer\n");
+#endif
+ return -ENOMEM;
+ }
+
+ lvc->ple_usage_bitmap_capacity = max_phys_leds;
+ lvc->ple_usage_bitmap = devm_kcalloc(dev, lvc->ple_usage_bitmap_capacity,
+ sizeof(*lvc->ple_usage_bitmap), GFP_KERNEL);
+ if (!lvc->ple_usage_bitmap) {
+#ifdef CONFIG_DEBUG_FS
+ dev_err(dev, "Failed to allocate PLE usage bitmap\n");
+#endif
+ return -ENOMEM;
+ }
+
+ controller_setup_debugfs(lvc);
+
+ /*
+ * PHASE 1: Initialize vLEDs and build internal list
+ *
+ * Uses generic fwnode child iteration to maintain the single OF bridge pattern.
+ * device_for_each_child_node() handles reference counting automatically.
+ */
+ device_for_each_child_node(dev, child_fwnode) {
+ /*
+ * virtual_led_init will call fwnode_handle_get() internally,
+ * so we pass the fwnode directly
+ */
+ vled = virtual_led_init(dev, child_fwnode, lvc);
+ if (IS_ERR(vled)) {
+ ret = PTR_ERR(vled);
+ dev_err(dev, "Failed to create LED from device node: %d\n", ret);
+
+ /* Handle deferred probe specially */
+ if (ret == -EPROBE_DEFER) {
+ dev_info(dev, "Deferring probe until LEDs are available\n");
+ fwnode_handle_put(child_fwnode);
+ controller_destroy_debugfs(lvc);
+ return -EPROBE_DEFER;
+ }
+ /* Loop continues, macro handles fwnode_handle_put */
+ continue;
+ }
+
+ mutex_lock(&lvc->lock);
+ list_add_tail(&vled->list, &lvc->leds);
+ mutex_unlock(&lvc->lock);
+
+ initialized_count++;
+ }
+
+ if (initialized_count == 0) {
+ ret = dev_err_probe(dev, -ENODEV, "No valid LED nodes found\n");
+ goto err_cleanup;
+ }
+
+ /*
+ * PHASE 2: Build physical LED mappings NOW.
+ * The controller is now in a consistent state.
+ */
+ mutex_lock(&lvc->lock);
+ controller_rebuild_phys_leds(lvc);
+ phys_count = lvc->phys_led_count;
+
+ if (phys_count > max_phys_leds) {
+ dev_warn(dev, "Physical LED count (%u) exceeds limit (%u)\n",
+ phys_count, max_phys_leds);
+ }
+ mutex_unlock(&lvc->lock);
+
+ /*
+ * Force all physical LEDs to known state (brightness=0).
+ *
+ * This is critical because:
+ * 1. Device tree may have boot LED aliases (linux,default-trigger = "default-on")
+ * 2. Physical LED drivers may restore previous brightness on probe
+ * 3. Without this, first arbitration compares current_brightness with chosen_brightness
+ * and skips update if they match (even though driver never set it)
+ *
+ * The first_arbitration flag helps, but DT triggers can activate LEDs AFTER
+ * our probe completes, so we must force them off here.
+ */
+ {
+ struct phys_led_entry *ple;
+ unsigned int reset_count = 0;
+
+ dev_info(dev, "Forcing %u physical LEDs to initial state (off)\n", phys_count);
+
+ mutex_lock(&lvc->lock);
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (!ple->cdev)
+ continue;
+
+ /* Force hardware to brightness=0 */
+ if (ple->cdev->brightness_set_blocking)
+ ple->cdev->brightness_set_blocking(ple->cdev, 0);
+ else if (ple->cdev->brightness_set)
+ ple->cdev->brightness_set(ple->cdev, 0);
+
+ /* Update driver's view to match hardware */
+ ple->cdev->brightness = 0;
+ reset_count++;
+
+ dev_dbg(dev, " Reset physical LED '%s' to brightness=0\n",
+ ple->cdev->name ? ple->cdev->name : "(unnamed)");
+ }
+ mutex_unlock(&lvc->lock);
+
+ if (reset_count > 0)
+ dev_info(dev, "Reset %u physical LEDs to off state\n", reset_count);
+ }
+
+ /*
+ * PHASE 3: Register vLEDs (expose to userspace)
+ * If registration fails, the device is shut down completely.
+ */
+ list_for_each_entry(vled, &lvc->leds, list) {
+ ret = virtual_led_register(dev, vled);
+ if (ret)
+ goto err_cleanup;
+ }
+
+ dev_info(dev, "Initialized %d virtual LED(s), controlling %u physical LEDs\n",
+ initialized_count, phys_count);
+
+ return 0;
+
+err_cleanup:
+ /*
+ * Release global ownership claims
+ * Must happen BEFORE destroying physical LED list to prevent
+ * use-after-free when iterating global_owner_xa.
+ */
+ global_release_all_for_pdev(pdev);
+
+ /*
+ * IMPORTANT: Since virtual_leds are kzalloc'd (not devm),
+ * we must clean them up manually on failure paths.
+ */
+ mutex_lock(&lvc->lock);
+
+ /* Destroy physical LED list and XArray first */
+ controller_destroy_phys_list(lvc);
+ xa_destroy(&lvc->phys_xa);
+
+ /* FIXED: Manually clean up vleds with explicit unregistration */
+ {
+ struct virtual_led *v, *tmp;
+
+ list_for_each_entry_safe(v, tmp, &lvc->leds, list) {
+ list_del(&v->list);
+
+ /* Explicitly unregister if registered to clean up sysfs immediately */
+ if (v->cdev_registered) {
+ led_classdev_unregister(&v->cdev);
+ v->cdev_registered = false;
+ }
+
+ /* Release device references before freeing vLED */
+ virtual_led_destroy(v);
+ /* This call uses kref_put() which leads to kfree(v) */
+ virtual_led_put(v);
+ }
+ }
+ mutex_unlock(&lvc->lock);
+
+ controller_destroy_debugfs(lvc);
+
+ /* devm will clean up the LVC structure itself */
+ return ret;
+}
+
+static void leds_virtualcolor_remove(struct platform_device *pdev)
+{
+ struct vcolor_controller *lvc;
+ struct virtual_led *vled, *tmp;
+
+ lvc = platform_get_drvdata(pdev);
+
+ if (!lvc)
+ return;
+
+ /* STEP 1: Signal removal FIRST */
+ atomic_set(&lvc->removing, 1);
+ smp_mb(); /* Memory barrier ensures visibility across CPUs */
+
+ /* STEP 2: Cancel delayed work */
+ cancel_delayed_work_sync(&lvc->update_work);
+
+ /* STEP 3: Wait for rebuild to complete - CRITICAL FIX */
+ while (atomic_read(&lvc->rebuilding))
+ msleep(20); /* Brief sleep to avoid busy-wait */
+
+ /*
+ * STEP 4: Wait for in-flight arbitration
+ * Now safe - rebuilding is complete, new ops prevented by removing flag
+ */
+ mutex_lock(&lvc->lock);
+ mutex_unlock(&lvc->lock);
+
+ /* Now safe to destroy physical LED list */
+ mutex_lock(&lvc->lock);
+ controller_destroy_phys_list(lvc);
+ xa_destroy(&lvc->phys_xa);
+ mutex_unlock(&lvc->lock);
+
+ list_for_each_entry_safe(vled, tmp, &lvc->leds, list) {
+ list_del(&vled->list);
+
+ /* Unregister LED class device before freeing vled memory */
+ if (vled->cdev_registered)
+ led_classdev_unregister(&vled->cdev);
+
+ virtual_led_destroy(vled);
+ virtual_led_put(vled);
+ }
+
+ global_release_all_for_pdev(pdev);
+ controller_destroy_debugfs(lvc);
+
+ dev_info(&pdev->dev, "Driver removed successfully\n");
+}
+
+static void leds_virtualcolor_shutdown(struct platform_device *pdev)
+{
+ struct vcolor_controller *lvc;
+ struct phys_led_entry *ple;
+
+ lvc = platform_get_drvdata(pdev);
+
+ if (!lvc)
+ return;
+
+ cancel_delayed_work_sync(&lvc->update_work);
+
+ mutex_lock(&lvc->lock);
+ atomic_set(&lvc->removing, 1);
+
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (ple->cdev) {
+ if (ple->cdev->brightness_set_blocking)
+ ple->cdev->brightness_set_blocking(ple->cdev, 0);
+ else if (ple->cdev->brightness_set)
+ ple->cdev->brightness_set(ple->cdev, 0);
+ }
+ }
+ controller_destroy_phys_list(lvc);
+
+ mutex_unlock(&lvc->lock);
+
+ dev_info(&pdev->dev, "Driver shutdown: all LEDs turned off\n");
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int leds_virtualcolor_suspend(struct device *dev)
+{
+ struct vcolor_controller *lvc;
+ struct phys_led_entry *ple;
+
+ lvc = dev_get_drvdata(dev);
+ if (!lvc)
+ return 0;
+
+ cancel_delayed_work_sync(&lvc->update_work);
+
+ mutex_lock(&lvc->lock);
+
+ /* FIX: Turn off all physical LEDs to save power */
+ list_for_each_entry(ple, &lvc->phys_leds, list) {
+ if (ple->cdev && ple->cdev->brightness > 0) {
+ if (ple->cdev->brightness_set_blocking)
+ ple->cdev->brightness_set_blocking(ple->cdev, 0);
+ else if (ple->cdev->brightness_set)
+ ple->cdev->brightness_set(ple->cdev, 0);
+ ple->cdev->brightness = 0;
+ }
+ }
+
+ lvc->suspended = true;
+ mutex_unlock(&lvc->lock);
+
+ dev_info(dev, "System suspended (LEDs turned off)\n");
+ return 0;
+}
+
+static int leds_virtualcolor_resume(struct device *dev)
+{
+ struct vcolor_controller *lvc;
+
+ lvc = dev_get_drvdata(dev);
+ if (!lvc)
+ return 0;
+
+ mutex_lock(&lvc->lock);
+ controller_rebuild_phys_leds(lvc);
+ lvc->suspended = false;
+ /* Lock released by controller_rebuild_phys_leds -> arbitration */
+
+ dev_info(dev, "System resumed\n");
+ return 0;
+}
+#else
+#define leds_virtualcolor_suspend NULL
+#define leds_virtualcolor_resume NULL
+#endif
+
+static const struct dev_pm_ops leds_virtualcolor_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(leds_virtualcolor_suspend, leds_virtualcolor_resume)
+};
+
+static const struct of_device_id leds_virtualcolor_dt_ids[] = {
+ { .compatible = "leds-group-virtualcolor" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, leds_virtualcolor_dt_ids);
+
+static struct platform_driver leds_virtualcolor_driver = {
+ .probe = leds_virtualcolor_probe,
+ .remove = leds_virtualcolor_remove,
+ .shutdown = leds_virtualcolor_shutdown,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = leds_virtualcolor_dt_ids,
+ .pm = &leds_virtualcolor_pm_ops,
+ },
+};
+
+static int __init leds_virtualcolor_init(void)
+{
+ int ret;
+
+ /* Validate and clamp module parameters */
+ if (update_delay_us > 1000000) {
+ pr_warn(DRIVER_NAME ": update_delay_us=%u exceeds max, clamping to 1000000\n",
+ update_delay_us);
+ update_delay_us = 1000000;
+ }
+
+ if (max_phys_leds < 1 || max_phys_leds > 1024) {
+ pr_warn(DRIVER_NAME ": max_phys_leds=%u out of range, using default %u\n",
+ max_phys_leds, MAX_PHYS_LEDS_DEFAULT);
+ max_phys_leds = MAX_PHYS_LEDS_DEFAULT;
+ }
+
+ pr_info(DRIVER_NAME ": v4 - Debug compilation optimization\n");
+ pr_info(DRIVER_NAME ": Config: gamma=%s, batching=%s, delay=%uus, max_leds=%u\n",
+ use_gamma_correction ? "on" : "off",
+ enable_update_batching ? "on" : "off",
+ update_delay_us, max_phys_leds);
+
+ ret = platform_driver_register(&leds_virtualcolor_driver);
+ if (ret) {
+ pr_err(DRIVER_NAME ": Failed to register platform driver: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+module_init(leds_virtualcolor_init);
+
+static void __exit leds_virtualcolor_exit(void)
+{
+ unsigned long index, leaked = 0;
+ struct global_phys_owner *gpo;
+
+ /* Unregister driver first to prevent new probes */
+ platform_driver_unregister(&leds_virtualcolor_driver);
+
+ /* Check for leaked ownership entries */
+ down_write(&global_owner_rwsem);
+
+ xa_for_each(&global_owner_xa, index, gpo) {
+ if (gpo && !xa_is_value(gpo)) {
+ pr_err(DRIVER_NAME
+ ": LEAK: Ownership entry at index %lu (pdev=%p) not freed\n",
+ index, gpo->owner_pdev);
+ leaked++;
+ }
+ }
+
+ if (leaked) {
+ pr_err(DRIVER_NAME ": %lu leaked entries detected at module exit\n", leaked);
+ pr_err(DRIVER_NAME ": This indicates controllers were not properly removed\n");
+ pr_err(DRIVER_NAME ": Memory leaked to prevent use-after-free corruption\n");
+ }
+
+ xa_destroy(&global_owner_xa);
+ up_write(&global_owner_rwsem);
+
+ pr_info(DRIVER_NAME ": Driver unloaded%s\n",
+ leaked ? " (with memory leaks - see errors above)" : " cleanly");
+}
+module_exit(leds_virtualcolor_exit);
+
+module_param(enable_debugfs, bool, 0444);
+MODULE_PARM_DESC(enable_debugfs,
+ "Enable debugfs interface for telemetry and testing (default: Y if CONFIG_DEBUG_FS)");
+
+module_param(use_gamma_correction, bool, 0644);
+MODULE_PARM_DESC(use_gamma_correction,
+ "Apply 2.2 gamma correction to brightness values (default: N)");
+
+module_param(update_delay_us, uint, 0644);
+MODULE_PARM_DESC(update_delay_us,
+ "Artificial delay in microseconds after each LED update batch (default: 0, max: 1000000)");
+
+module_param(max_phys_leds, uint, 0444);
+MODULE_PARM_DESC(max_phys_leds,
+ "Maximum unique physical LEDs per controller (default: 64, range: 1-1024)");
+
+module_param(enable_update_batching, bool, 0644);
+MODULE_PARM_DESC(enable_update_batching,
+ "Batch brightness updates with 10ms delay to reduce CPU overhead (default: N)");
+
+MODULE_AUTHOR("Jonathan Brophy <professor_jonny@...mail.com>");
+MODULE_DESCRIPTION("Virtual grouped LED driver with multicolor ABI V4");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("4");
--
2.43.0
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