Re: [PATCH v6 6/7] platform/x86: asus-wmi: add keyboard brightness event handler

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Mon, 13 Oct 2025, Antheas Kapenekakis wrote:

> Currenlty, the keyboard brightness control of Asus WMI keyboards is

There's a typo here but preferrably avoid "currently" altogether where 
possible.

> handled in the kernel, which leads to the shortcut going from
> brightness 0, to 1, to 2, and 3.
> 
> However, for HID keyboards it is exposed as a key and handled by the
> user's desktop environment. For the toggle button, this means that
> brightness control becomes on/off. In addition, in the absence of a
> DE, the keyboard brightness does not work.
> 
> Therefore, expose an event handler for the keyboard brightness control
> which can then be used by hid-asus.
> 
> 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            | 41 +++++++++++++++++++++-
>  include/linux/platform_data/x86/asus-wmi.h | 13 +++++++
>  2 files changed, 53 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index a2a7cd61fd59..58407a3b6d41 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -1579,6 +1579,45 @@ void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
>  }
>  EXPORT_SYMBOL_GPL(asus_hid_unregister_listener);
>  
> +static void do_kbd_led_set(struct led_classdev *led_cdev, int value);
> +
> +int asus_hid_event(enum asus_hid_event event)
> +{
> +	unsigned long flags;
> +	int brightness;
> +
> +	spin_lock_irqsave(&asus_ref.lock, flags);
> +	if (!asus_ref.asus || !asus_ref.asus->kbd_led_registered) {

Please add a local variable for asus_ref.asus. Check other 
patches/functions too if its use is repeated in some function many times, 
the local var seems to be in order.

> +		spin_unlock_irqrestore(&asus_ref.lock, flags);

Use guard() instead.

> +		return -EBUSY;
> +	}
> +	brightness = asus_ref.asus->kbd_led_wk;
> +
> +	switch (event) {
> +	case ASUS_EV_BRTUP:
> +		brightness += 1;
> +		break;
> +	case ASUS_EV_BRTDOWN:
> +		brightness -= 1;
> +		break;
> +	case ASUS_EV_BRTTOGGLE:
> +		if (brightness >= ASUS_EV_MAX_BRIGHTNESS)
> +			brightness = 0;
> +		else
> +			brightness += 1;
> +		break;
> +	}
> +
> +	do_kbd_led_set(&asus_ref.asus->kbd_led, brightness);
> +	led_classdev_notify_brightness_hw_changed(&asus_ref.asus->kbd_led,
> +						  asus_ref.asus->kbd_led_wk);
> +
> +	spin_unlock_irqrestore(&asus_ref.lock, flags);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(asus_hid_event);
> +
>  /*
>   * These functions actually update the LED's, and are called from a
>   * workqueue. By doing this as separate work rather than when the LED
> @@ -1878,7 +1917,7 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
>  	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.max_brightness = ASUS_EV_MAX_BRIGHTNESS;
>  	asus->kbd_led_avail = !kbd_led_read(asus, &led_val, NULL);
>  
>  	if (asus->kbd_led_avail)
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 1f85d76387a8..e78e0fbccede 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -168,6 +168,14 @@ struct asus_hid_listener {
>  	void (*brightness_set)(struct asus_hid_listener *listener, int brightness);
>  };
>  
> +enum asus_hid_event {
> +	ASUS_EV_BRTUP,
> +	ASUS_EV_BRTDOWN,
> +	ASUS_EV_BRTTOGGLE,

Where does "BRT" come from. To me it doesn't associate with brightness 
(might be due to me being non-native). If there's a good reason why it's 
that way, fine but otherwise I suggest changing it so that it becomes 
easier to understand.

It's not a big problem as is because the context in the code above allows 
decrypting the meaning but without the other names, I'd have been totally 
lost what it means.

> +};
> +
> +#define ASUS_EV_MAX_BRIGHTNESS 3
> +
>  #if IS_REACHABLE(CONFIG_ASUS_WMI)
>  void set_ally_mcu_hack(enum asus_ally_mcu_hack status);
>  void set_ally_mcu_powersave(bool enabled);
> @@ -176,6 +184,7 @@ 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);
> +int asus_hid_event(enum asus_hid_event event);
>  #else
>  static inline void set_ally_mcu_hack(enum asus_ally_mcu_hack status)
>  {
> @@ -200,6 +209,10 @@ static inline int asus_hid_register_listener(struct asus_hid_listener *bdev)
>  static inline void asus_hid_unregister_listener(struct asus_hid_listener *bdev)
>  {
>  }
> +static inline int asus_hid_event(enum asus_hid_event event)
> +{
> +	return -ENODEV;
> +}
>  #endif
>  
>  #endif	/* __PLATFORM_DATA_X86_ASUS_WMI_H */
> 

-- 
 i.