Re: [PATCH v3 04/10] platform/x86: asus-wmi: Add support for multiple kbd RGB handlers

[Hans de Goede]

Hi Antheas,

Note not a full review, just taking a generic look at the new API
between asus-wmi and asus-hid.

On 22-Mar-25 11:27, 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.
> 
> Signed-off-by: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
> ---
>  drivers/platform/x86/asus-wmi.c            | 113 ++++++++++++++++++---
>  include/linux/platform_data/x86/asus-wmi.h |  16 +++
>  2 files changed, 117 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index 38ef778e8c19b..95ef9b1d321bb 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -254,6 +254,8 @@ 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;
> @@ -1487,6 +1489,53 @@ 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;
> +};
> +
> +struct asus_hid_ref asus_ref = {
> +	.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;
> +		}
> +	}
> +	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
> @@ -1566,6 +1615,7 @@ 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;
>  
> @@ -1573,25 +1623,39 @@ 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;
>  
>  	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)
> @@ -1601,6 +1665,9 @@ 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;
> @@ -1716,7 +1783,14 @@ 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;
> +	if (asus->kbd_led_registered)
> +		led_classdev_unregister(&asus->kbd_led);
> +	spin_unlock_irqrestore(&asus_ref.lock, flags);
> +
>  	led_classdev_unregister(&asus->tpd_led);
>  	led_classdev_unregister(&asus->wlan_led);
>  	led_classdev_unregister(&asus->lightbar_led);
> @@ -1730,6 +1804,8 @@ 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;
> +	unsigned long flags;
> +	bool has_listeners;
>  
>  	if (asus->kbd_rgb_dev)
>  		kbd_rgb_mode_groups[num_rgb_groups++] = &kbd_rgb_mode_group;
> @@ -1754,24 +1830,37 @@ 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 (asus->kbd_led_avail && num_rgb_groups != 0)
> +		asus->kbd_led.groups = kbd_rgb_mode_groups;
>  
> -		if (num_rgb_groups != 0)
> -			asus->kbd_led.groups = kbd_rgb_mode_groups;
> +	spin_lock_irqsave(&asus_ref.lock, flags);
> +	has_listeners = !list_empty(&asus_ref.listeners);
> +	spin_unlock_irqrestore(&asus_ref.lock, flags);

It seems to me that you should also call brightness_set()
on all the kbds already in the list so that their brightness
gets synced with the wmi kbd-backlight brightness when
the wmi driver loads later then the hid driver ?

>  
> +	if (asus->kbd_led_avail || has_listeners) {
>  		rv = led_classdev_register(&asus->platform_device->dev,
>  					   &asus->kbd_led);
>  		if (rv)
>  			goto error;
> +		asus->kbd_led_registered = true;
>  	}
>  
> +	spin_lock_irqsave(&asus_ref.lock, flags);
> +	asus_ref.asus = asus;

There is race here where a hid keyboard might show up between
the 2 places you take the lock, in that case if there is
no wmi kbd-backlight then you will not register the led_classdev
when asus_hid_register_listener() gets called between the unlock
and the lock...  I'm not sure what the best way is to fix this.

Regards,

Hans



> +	spin_unlock_irqrestore(&asus_ref.lock, flags);
> +
>  	if (asus_wmi_dev_is_present(asus, ASUS_WMI_DEVID_WIRELESS_LED)
>  			&& (asus->driver->quirks->wapf > 0)) {
>  		INIT_WORK(&asus->wlan_led_work, wlan_led_update);
> diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
> index 783e2a336861b..ec8b0c585a63f 100644
> --- a/include/linux/platform_data/x86/asus-wmi.h
> +++ b/include/linux/platform_data/x86/asus-wmi.h
> @@ -157,14 +157,30 @@
>  #define ASUS_WMI_DSTS_MAX_BRIGTH_MASK	0x0000FF00
>  #define ASUS_WMI_DSTS_LIGHTBAR_MASK	0x0000000F
>  
> +struct asus_hid_listener {
> +	struct list_head list;
> +	void (*brightness_set)(struct asus_hid_listener *listener, int brightness);
> +};
> +
>  #if IS_REACHABLE(CONFIG_ASUS_WMI)
>  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 int asus_wmi_evaluate_method(u32 method_id, u32 arg0, u32 arg1,
>  					   u32 *retval)
>  {
>  	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 */