Re: [PATCH v6 3/7] platform/x86: asus-wmi: Add support for multiple kbd RGB handlers

Ilpo Järvinen
2025-10-15T11:59:41Z

On Mon, 13 Oct 2025, 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.
>
> Reviewed-by: Luke D. Jones <luke@ljones.dev>
> Tested-by: Luke D. Jones <luke@ljones.dev>
> Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
> drivers/platform/x86/asus-wmi.c | 118 ++++++++++++++++++---
> include/linux/platform_data/x86/asus-wmi.h | 16 +++
> 2 files changed, 121 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index e72a2b5d158e..a2a7cd61fd59 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -258,6 +258,8 @@ struct asus_wmi {
> int tpd_led_wk;
> struct led_classdev kbd_led;
> int kbd_led_wk;
> + bool kbd_led_avail;
> + bool kbd_led_registered;
> struct led_classdev lightbar_led;
> int lightbar_led_wk;
> struct led_classdev micmute_led;
> @@ -1530,6 +1532,53 @@ static void asus_wmi_battery_exit(struct asus_wmi *asus)
>
> /* LEDs ***********************************************************************/
>
> +struct asus_hid_ref {
> + struct list_head listeners;
> + struct asus_wmi *asus;
> + spinlock_t lock;

Please always document what a lock protects.

I started wonder why it needs to be spinlock?

It would seem rwsem is more natural for it as write is only needed at
probe/remove time (if there's no good reason for using a spinlock).

You're also missing include.

> +};
> +
> +struct asus_hid_ref asus_ref = {

Should be static ?

> + .listeners = LIST_HEAD_INIT(asus_ref.listeners),
> + .asus = NULL,
> + .lock = __SPIN_LOCK_UNLOCKED(asus_ref.lock),
> +};
> +
> +int asus_hid_register_listener(struct asus_hid_listener *bdev)
> +{
> + unsigned long flags;
> + int ret = 0;
> +
> + spin_lock_irqsave(&asus_ref.lock, flags);
> + list_add_tail(&bdev->list, &asus_ref.listeners);
> + if (asus_ref.asus) {
> + if (asus_ref.asus->kbd_led_registered && asus_ref.asus->kbd_led_wk >= 0)
> + bdev->brightness_set(bdev, asus_ref.asus->kbd_led_wk);
> +
> + if (!asus_ref.asus->kbd_led_registered) {
> + ret = led_classdev_register(
> + &asus_ref.asus->platform_device->dev,
> + &asus_ref.asus->kbd_led);
> + if (!ret)
> + asus_ref.asus->kbd_led_registered = true;

I suggest you use guard() for the spinlock and return early where possible.

With guard() in use, you can do normal error handling here with return ret
immediately.

Please also add a local var for asus_ref.asus.

> + }
> + }
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_register_listener);
> +
> +void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&asus_ref.lock, flags);
> + list_del(&bdev->list);
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_unregister_listener);
> +
> /*
> * These functions actually update the LED's, and are called from a
> * workqueue. By doing this as separate work rather than when the LED
> @@ -1609,6 +1658,7 @@ 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;
>
> @@ -1616,25 +1666,39 @@ static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
> max_level = asus->kbd_led.max_brightness;
>
> asus->kbd_led_wk = clamp_val(value, 0, max_level);
> - kbd_led_update(asus);
> +
> + if (asus->kbd_led_avail)
> + kbd_led_update(asus);
> +
> + 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,
> enum led_brightness value)
> {
> + unsigned long flags;
> +
> /* Prevent disabling keyboard backlight on module unregister */
> if (led_cdev->flags & LED_UNREGISTERING)
> return;
>
> + spin_lock_irqsave(&asus_ref.lock, flags);
> do_kbd_led_set(led_cdev, value);
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
> }
>
> static void kbd_led_set_by_kbd(struct asus_wmi *asus, enum led_brightness value)
> {
> - struct led_classdev *led_cdev = &asus->kbd_led;
> + struct led_classdev *led_cdev;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&asus_ref.lock, flags);
> + led_cdev = &asus->kbd_led;
>

I'd remove the empty line from the critical section.

I think you should mention the locking in the changelog too as it clearly
impacts not only the new code.

> do_kbd_led_set(led_cdev, value);
> led_classdev_notify_brightness_hw_changed(led_cdev, asus->kbd_led_wk);
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
> }
>
> static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
> @@ -1644,6 +1708,9 @@ static enum led_brightness kbd_led_get(struct led_classdev *led_cdev)
>
> asus = container_of(led_cdev, struct asus_wmi, kbd_led);
>
> + if (!asus->kbd_led_avail)
> + return asus->kbd_led_wk;
> +
> retval = kbd_led_read(asus, &value, NULL);
> if (retval < 0)
> return retval;
> @@ -1759,7 +1826,15 @@ 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);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&asus_ref.lock, flags);
> + asus_ref.asus = NULL;
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
> +
> + if (asus->kbd_led_registered)
> + led_classdev_unregister(&asus->kbd_led);
> +
> led_classdev_unregister(&asus->tpd_led);
> led_classdev_unregister(&asus->wlan_led);
> led_classdev_unregister(&asus->lightbar_led);
> @@ -1773,6 +1848,8 @@ static void asus_wmi_led_exit(struct asus_wmi *asus)
> static int asus_wmi_led_init(struct asus_wmi *asus)
> {
> int rv = 0, num_rgb_groups = 0, led_val;
> + struct asus_hid_listener *listener;
> + unsigned long flags;
>
> if (asus->kbd_rgb_dev)
> kbd_rgb_mode_groups[num_rgb_groups++] = &kbd_rgb_mode_group;
> @@ -1797,23 +1874,38 @@ 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.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);
> +
> + if (asus->kbd_led_avail)
> 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;
> + else
> + asus->kbd_led_wk = -1;
>
> - if (num_rgb_groups != 0)
> - asus->kbd_led.groups = kbd_rgb_mode_groups;
> + if (asus->kbd_led_avail && num_rgb_groups != 0)
> + asus->kbd_led.groups = kbd_rgb_mode_groups;

Can't this be placed into the block above?

>
> + spin_lock_irqsave(&asus_ref.lock, flags);
> + if (asus->kbd_led_avail || !list_empty(&asus_ref.listeners)) {
> rv = led_classdev_register(&asus->platform_device->dev,
> &asus->kbd_led);
> - if (rv)
> + if (rv) {
> + spin_unlock_irqrestore(&asus_ref.lock, flags);

Please use scoped_guard() so you don't need to call unlock yourself.

Unrelated to this patch, I'd also simplify error label by adding return 0
before it so the code after the label doesn't need if (rv) check.

> goto error;
> + }
> + asus->kbd_led_registered = true;
> +
> + if (asus->kbd_led_wk >= 0) {
> + list_for_each_entry(listener, &asus_ref.listeners, list)
> + listener->brightness_set(listener, asus->kbd_led_wk);
> + }
> }
> + asus_ref.asus = asus;
> + spin_unlock_irqrestore(&asus_ref.lock, flags);
>
> if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_WIRELESS_LED)
> && (asus->driver->quirks->wapf > 0)) {
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 8a515179113d..f13a701f47a8 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -163,11 +163,19 @@ enum asus_ally_mcu_hack {
> ASUS_WMI_ALLY_MCU_HACK_DISABLED,
> };
>
> +struct asus_hid_listener {
> + struct list_head list;
> + void (*brightness_set)(struct asus_hid_listener *listener, int brightness);
> +};

Please add kerneldoc to this struct and the exported functions.

> +
> #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 +192,14 @@ 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 */
>

--
i.