Re: [PATCH v9 07/11] platform/x86: asus-wmi: Add support for multiple kbd led handlers

Denis Benato
2025-11-20T13:46:20Z

On 11/20/25 10:46, Antheas Kapenekakis wrote:
> Some devices, such as the Z13 have multiple Aura devices connected
> to them by USB. In addition, they might have a WMI interface for
> RGB. In Windows, Armoury Crate exposes a unified brightness slider
> for all of them, with 3 brightness levels.
>
> Therefore, to be synergistic in Linux, and support existing tooling
> such as UPower, allow adding listeners to the RGB device of the WMI
> interface. If WMI does not exist, lazy initialize the interface.
>
> Since hid-asus and asus-wmi can both interact with the led objects
> including from an atomic context, protect the brightness access with a
> spinlock and update the values from a workqueue. Use this workqueue to
> also process WMI keyboard events, so they are handled asynchronously.
>
> Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
> drivers/platform/x86/asus-wmi.c | 174 ++++++++++++++++++---
> include/linux/platform_data/x86/asus-wmi.h | 17 ++
> 2 files changed, 167 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index e72a2b5d158e..5f23aedbf34f 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -36,6 +36,7 @@
> #include <linux/rfkill.h>
> #include <linux/seq_file.h>
> #include <linux/slab.h>
> +#include <linux/spinlock.h>
> #include <linux/types.h>
> #include <linux/units.h>
>
> @@ -258,6 +259,9 @@ struct asus_wmi {
> int tpd_led_wk;
> struct led_classdev kbd_led;
> int kbd_led_wk;
> + bool kbd_led_notify;
> + bool kbd_led_avail;
> + bool kbd_led_registered;
> struct led_classdev lightbar_led;
> int lightbar_led_wk;
> struct led_classdev micmute_led;
> @@ -266,6 +270,7 @@ struct asus_wmi {
> struct work_struct tpd_led_work;
> struct work_struct wlan_led_work;
> struct work_struct lightbar_led_work;
> + struct work_struct kbd_led_work;
>
> struct asus_rfkill wlan;
> struct asus_rfkill bluetooth;
> @@ -1530,6 +1535,99 @@ static void asus_wmi_battery_exit(struct asus_wmi *asus)
>
> /* LEDs ***********************************************************************/
>
> +struct asus_hid_ref {
> + struct list_head listeners;
> + struct asus_wmi *asus;
> + /* Protects concurrent access from hid-asus and asus-wmi to leds */
> + spinlock_t lock;
> +};
> +
> +static struct asus_hid_ref asus_ref = {
> + .listeners = LIST_HEAD_INIT(asus_ref.listeners),
> + .asus = NULL,
> + /*
> + * Protects .asus, .asus.kbd_led_{wk,notify}, and .listener refs. Other
> + * asus variables are read-only after .asus is set. Except the led cdev
> + * device if not kbd_led_avail. That becomes read-only after the
> + * first hid-asus listener registers and triggers the work queue. It is
> + * then not referenced again until unregistering, which happens after
> + * .asus ref is dropped. Since .asus needs to be accessed by hid-asus
> + * IRQs to check if forwarding events is possible, a spinlock is used.
> + */
What are "That" and "It" referring to in this context?

Are you absolutely sure you want to begin a sentence with "Except"?

On "ref is dropped" I would continue with ": since .asus .....".
> + .lock = __SPIN_LOCK_UNLOCKED(asus_ref.lock),
> +};
> +
> +/*
> + * Allows registering hid-asus listeners that want to be notified of
> + * keyboard backlight changes.
> + */
> +int asus_hid_register_listener(struct asus_hid_listener *bdev)
> +{
> + struct asus_wmi *asus;
> +
> + guard(spinlock_irqsave)(&asus_ref.lock);
> + list_add_tail(&bdev->list, &asus_ref.listeners);
> + asus = asus_ref.asus;
> + if (asus)
> + queue_work(asus->led_workqueue, &asus->kbd_led_work);
Are you sure this has to be protected by the guard too?
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_register_listener);
> +
> +/*
> + * Allows unregistering hid-asus listeners that were added with
> + * asus_hid_register_listener().
> + */
> +void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
> +{
> + guard(spinlock_irqsave)(&asus_ref.lock);
> + list_del(&bdev->list);
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_unregister_listener);
> +
> +static void do_kbd_led_set(struct led_classdev *led_cdev, int value);
> +
> +static void kbd_led_update_all(struct work_struct *work)
> +{
> + struct asus_wmi *asus;
> + bool registered, notify;
> + int ret, value;
> +
> + asus = container_of(work, struct asus_wmi, kbd_led_work);
> +
> + scoped_guard(spinlock_irqsave, &asus_ref.lock) {
> + registered = asus->kbd_led_registered;
> + value = asus->kbd_led_wk;
> + notify = asus->kbd_led_notify;
> + }
> +
> + if (!registered) {
> + /*
> + * This workqueue runs under asus-wmi, which means probe has
> + * completed and asus-wmi will keep running until it finishes.
> + * Therefore, we can safely register the LED without holding
> + * a spinlock.
> + */
> + ret = devm_led_classdev_register(&asus->platform_device->dev,
> + &asus->kbd_led);
> + if (!ret) {
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + asus->kbd_led_registered = true;
> + } else {
> + pr_warn("Failed to register keyboard backlight LED: %d\n", ret);
> + return;
> + }
> + }
> +
> + if (value >= 0)
> + do_kbd_led_set(&asus->kbd_led, value);
> + if (notify) {
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + asus->kbd_led_notify = false;
> + led_classdev_notify_brightness_hw_changed(&asus->kbd_led, value);
> + }
> +}
> +
> /*
> * These functions actually update the LED's, and are called from a
> * workqueue. By doing this as separate work rather than when the LED
> @@ -1576,7 +1674,8 @@ static void kbd_led_update(struct asus_wmi *asus)
> {
> int ctrl_param = 0;
>
> - ctrl_param = 0x80 | (asus->kbd_led_wk & 0x7F);
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + ctrl_param = 0x80 | (asus->kbd_led_wk & 0x7F);
> asus_wmi_set_devstate(ASUS_WMI_DEVID_KBD_BACKLIGHT, ctrl_param, NULL);
> }
>
> @@ -1609,14 +1708,23 @@ static int kbd_led_read(struct asus_wmi *asus, int *level, int *env)
>
> static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
> {
> + struct asus_hid_listener *listener;
> struct asus_wmi *asus;
> int max_level;
>
> asus = container_of(led_cdev, struct asus_wmi, kbd_led);
> max_level = asus->kbd_led.max_brightness;
>
> - asus->kbd_led_wk = clamp_val(value, 0, max_level);
> - kbd_led_update(asus);
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + asus->kbd_led_wk = clamp_val(value, 0, max_level);
> +
> + if (asus->kbd_led_avail)
> + kbd_led_update(asus);
> +
> + scoped_guard(spinlock_irqsave, &asus_ref.lock) {
> + list_for_each_entry(listener, &asus_ref.listeners, list)
> + listener->brightness_set(listener, asus->kbd_led_wk);
> + }
> }
>
> static void kbd_led_set(struct led_classdev *led_cdev,
> @@ -1631,10 +1739,11 @@ static void kbd_led_set(struct led_classdev *led_cdev,
>
> static void kbd_led_set_by_kbd(struct asus_wmi *asus, enum led_brightness value)
> {
> - struct led_classdev *led_cdev = &asus->kbd_led;
> -
> - do_kbd_led_set(led_cdev, value);
> - led_classdev_notify_brightness_hw_changed(led_cdev, asus->kbd_led_wk);
> + scoped_guard(spinlock_irqsave, &asus_ref.lock) {
> + asus->kbd_led_wk = value;
> + asus->kbd_led_notify = true;
> + }
> + queue_work(asus->led_workqueue, &asus->kbd_led_work);
> }
>
> static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
> @@ -1644,10 +1753,18 @@ static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
>
> asus = container_of(led_cdev, struct asus_wmi, kbd_led);
>
> + scoped_guard(spinlock_irqsave, &asus_ref.lock) {
> + if (!asus->kbd_led_avail)
> + return asus->kbd_led_wk;
> + }
> +
> retval = kbd_led_read(asus, &value, NULL);
> if (retval < 0)
> return retval;
>
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + asus->kbd_led_wk = value;
> +
> return value;
> }
>
> @@ -1759,7 +1876,9 @@ static int camera_led_set(struct led_classdev *led_cdev,
>
> static void asus_wmi_led_exit(struct asus_wmi *asus)
> {
> - led_classdev_unregister(&asus->kbd_led);
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + asus_ref.asus = NULL;
> +
> led_classdev_unregister(&asus->tpd_led);
> led_classdev_unregister(&asus->wlan_led);
> led_classdev_unregister(&asus->lightbar_led);
> @@ -1797,22 +1916,25 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
> goto error;
> }
>
> - if (!kbd_led_read(asus, &led_val, NULL) && !dmi_check_system(asus_use_hid_led_dmi_ids)) {
> - pr_info("using asus-wmi for asus::kbd_backlight\n");
> - asus->kbd_led_wk = led_val;
> - asus->kbd_led.name = "asus::kbd_backlight";
> - asus->kbd_led.flags = LED_BRIGHT_HW_CHANGED;
> - asus->kbd_led.brightness_set = kbd_led_set;
> - asus->kbd_led.brightness_get = kbd_led_get;
> - asus->kbd_led.max_brightness = 3;
> + asus->kbd_led.name = "asus::kbd_backlight";
> + asus->kbd_led.flags = LED_BRIGHT_HW_CHANGED;
> + asus->kbd_led.brightness_set = kbd_led_set;
> + asus->kbd_led.brightness_get = kbd_led_get;
> + asus->kbd_led.max_brightness = 3;
> + asus->kbd_led_avail = !kbd_led_read(asus, &led_val, NULL);
> + INIT_WORK(&asus->kbd_led_work, kbd_led_update_all);
>
> + if (asus->kbd_led_avail) {
> + asus->kbd_led_wk = led_val;
> if (num_rgb_groups != 0)
> asus->kbd_led.groups = kbd_rgb_mode_groups;
> + } else
> + asus->kbd_led_wk = -1;
>
> - rv = led_classdev_register(&asus->platform_device->dev,
> - &asus->kbd_led);
> - if (rv)
> - goto error;
> + scoped_guard(spinlock_irqsave, &asus_ref.lock) {
> + asus_ref.asus = asus;
> + if (asus->kbd_led_avail || !list_empty(&asus_ref.listeners))
> + queue_work(asus->led_workqueue, &asus->kbd_led_work);
> }
>
> if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_WIRELESS_LED)
> @@ -4272,6 +4394,7 @@ static int asus_wmi_get_event_code(union acpi_object *obj)
>
> static void asus_wmi_handle_event_code(int code, struct asus_wmi *asus)
> {
> + enum led_brightness led_value;
> unsigned int key_value = 1;
> bool autorelease = 1;
>
> @@ -4288,19 +4411,22 @@ static void asus_wmi_handle_event_code(int code, struct asus_wmi *asus)
> return;
> }
>
> + scoped_guard(spinlock_irqsave, &asus_ref.lock)
> + led_value = asus->kbd_led_wk;
> +
> if (code == NOTIFY_KBD_BRTUP) {
> - kbd_led_set_by_kbd(asus, asus->kbd_led_wk + 1);
> + kbd_led_set_by_kbd(asus, led_value + 1);
> return;
> }
> if (code == NOTIFY_KBD_BRTDWN) {
> - kbd_led_set_by_kbd(asus, asus->kbd_led_wk - 1);
> + kbd_led_set_by_kbd(asus, led_value - 1);
> return;
> }
> if (code == NOTIFY_KBD_BRTTOGGLE) {
> - if (asus->kbd_led_wk == asus->kbd_led.max_brightness)
> + if (led_value == asus->kbd_led.max_brightness)
> kbd_led_set_by_kbd(asus, 0);
> else
> - kbd_led_set_by_kbd(asus, asus->kbd_led_wk + 1);
> + kbd_led_set_by_kbd(asus, led_value + 1);
> return;
> }
>
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 8a515179113d..1165039013b1 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -163,11 +163,20 @@ enum asus_ally_mcu_hack {
> ASUS_WMI_ALLY_MCU_HACK_DISABLED,
> };
>
> +/* Used to notify hid-asus when asus-wmi changes keyboard backlight */
> +struct asus_hid_listener {
> + struct list_head list;
> + void (*brightness_set)(struct asus_hid_listener *listener, int brightness);
> +};
> +
> #if IS_REACHABLE(CONFIG_ASUS_WMI)
> void set_ally_mcu_hack(enum asus_ally_mcu_hack status);
> void set_ally_mcu_powersave(bool enabled);
> int asus_wmi_set_devstate(u32 dev_id, u32 ctrl_param, u32 *retval);
> int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1, u32 *retval);
> +
> +int asus_hid_register_listener(struct asus_hid_listener *cdev);
> +void asus_hid_unregister_listener(struct asus_hid_listener *cdev);
> #else
> static inline void set_ally_mcu_hack(enum asus_ally_mcu_hack status)
> {
> @@ -184,6 +193,14 @@ static inline int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1,
> {
> return -ENODEV;
> }
> +
> +static inline int asus_hid_register_listener(struct asus_hid_listener *bdev)
> +{
> + return -ENODEV;
> +}
> +static inline void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
> +{
> +}
> #endif
>
> /* To be used by both hid-asus and asus-wmi to determine which controls kbd_brightness */