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Message-ID: <2f7c8e80-274e-4cec-98bf-cd9cc49fb363@linux.dev>
Date: Sat, 17 Jan 2026 14:56:04 +0100
From: Denis Benato <denis.benato@...ux.dev>
To: Antheas Kapenekakis <lkml@...heas.dev>
Cc: platform-driver-x86@...r.kernel.org, linux-input@...r.kernel.org,
linux-kernel@...r.kernel.org, Jiri Kosina <jikos@...nel.org>,
Benjamin Tissoires <bentiss@...nel.org>,
Corentin Chary <corentin.chary@...il.com>, "Luke D . Jones"
<luke@...nes.dev>, Hans de Goede <hansg@...nel.org>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v11 07/11] platform/x86: asus-wmi: Add support for
multiple kbd led handlers
On 1/17/26 14:49, Antheas Kapenekakis wrote:
> On Sat, 17 Jan 2026 at 14:16, Denis Benato <denis.benato@...ux.dev> wrote:
>>
>> On 1/16/26 14:31, 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.
>>>
>>> Acked-by: Benjamin Tissoires <bentiss@...nel.org>
>>> Signed-off-by: Antheas Kapenekakis <lkml@...heas.dev>
>>> ---
>>> drivers/platform/x86/asus-wmi.c | 183 ++++++++++++++++++---
>>> include/linux/platform_data/x86/asus-wmi.h | 15 ++
>>> 2 files changed, 173 insertions(+), 25 deletions(-)
>>>
>>> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
>>> index 4aec7ec69250..df2365efb2b8 100644
>>> --- a/drivers/platform/x86/asus-wmi.c
>>> +++ b/drivers/platform/x86/asus-wmi.c
>>> @@ -31,13 +31,13 @@
>>> #include <linux/pci.h>
>>> #include <linux/pci_hotplug.h>
>>> #include <linux/platform_data/x86/asus-wmi.h>
>>> -#include <linux/platform_data/x86/asus-wmi-leds-ids.h>
>>> #include <linux/platform_device.h>
>>> #include <linux/platform_profile.h>
>>> #include <linux/power_supply.h>
>>> #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>
>>>
>>> @@ -256,6 +256,9 @@ 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;
>>> @@ -264,6 +267,7 @@ 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;
>>> @@ -1615,6 +1619,106 @@ 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.
>>> + *
>>> + * The led cdev device is not protected because it calls backlight_get
>>> + * during initialization, which would result in a nested lock attempt.
>>> + *
>>> + * The led cdev is safe to access without a lock because if
>>> + * kbd_led_avail is true it is initialized before .asus is set and never
>>> + * changed until .asus is dropped. If kbd_led_avail is false, the led
>>> + * cdev is registered by the workqueue, which is single-threaded and
>>> + * cancelled before asus-wmi would access the led cdev to unregister it.
>>> + *
>>> + * A spinlock is used, because the protected variables can be accessed
>>> + * from an IRQ context from asus-hid.
>>> + */
>>> + .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);
>>> + 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
>>> @@ -1661,7 +1765,8 @@ 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);
>>> }
>>>
>>> @@ -1694,14 +1799,23 @@ 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 int kbd_led_set(struct led_classdev *led_cdev, enum led_brightness value)
>>> @@ -1716,10 +1830,11 @@ static int kbd_led_set(struct led_classdev *led_cdev, enum led_brightness value)
>>>
>>> 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)
>>> @@ -1729,10 +1844,18 @@ 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;
>>> }
>>>
>>> @@ -1844,7 +1967,9 @@ 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);
>>> @@ -1882,22 +2007,26 @@ 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_blocking = 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_blocking = 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)
>>> @@ -4372,6 +4501,7 @@ 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;
>>>
>>> @@ -4388,19 +4518,22 @@ 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);
>> This is the toggle leds button, right? I would expect that pressing the toggle
>> button turns off leds if they are on and turns them on if they are off.
>>
>> so if (led_value > 0) { .... }.
>>
>> I see the previous code was equivalent to yours but is that what we want?
> It is common to do 0->1->2->3->0 for the toggle. This is what is
> currently done for WMI Asus keyboards and e.g., Thinkpads. This patch
> unifies the behavior for USB keyboards too.
>
> I would argue it is better, as you do not need to reach for a
> userspace slider to set a lower brightness.
>
> The current behavior of KDE is 0->3->0 and if the event goes to
> userspace this is what happens currently. Unless the keyboard
> reconnects, where brightness just stops working afterwards because
> upower only probes at boot (I have a follow patch to fix this for
> Duos).
Whatever goes for me if hid and wmi handles them the same,
especially if userspace does the same thing.
In 11/11 you do:
caseASUS_EV_BRTTOGGLE:
if(brightness >=ASUS_EV_MAX_BRIGHTNESS)
brightness =0;
else
brightness +=1;
break;
}
So perhaps here you should do
if (led_value >= asus->kbd_led.max_brightness)
purely for consistency?
> Antheas
>
>>> 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 419491d4abca..d347cffd05d5 100644
>>> --- a/include/linux/platform_data/x86/asus-wmi.h
>>> +++ b/include/linux/platform_data/x86/asus-wmi.h
>>> @@ -172,12 +172,20 @@ 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_get_devstate_dsts(u32 dev_id, u32 *retval);
>>> 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)
>>> {
>>> @@ -198,6 +206,13 @@ 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
>>>
>>> #endif /* __PLATFORM_DATA_X86_ASUS_WMI_H */
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