Re: [PATCH v2] platform/x86: asus-wmi: use brightness_set_blocking() for kbd led

[Denis Benato <benato.denis96@gmail.com>]

On 11/29/25 11:13, Anton Khirnov wrote:
> kbd_led_set() can sleep, and so may not be used as the brightness_set()
> callback.
>
> Otherwise using this led with a trigger leads to system hangs
> accompanied by:
> BUG: scheduling while atomic: acpi_fakekeyd/2588/0x00000003
> CPU: 4 UID: 0 PID: 2588 Comm: acpi_fakekeyd Not tainted 6.17.9+deb14-amd64 #1 PREEMPT(lazy)  Debian 6.17.9-1
> Hardware name: ASUSTeK COMPUTER INC. ASUS EXPERTBOOK B9403CVAR/B9403CVAR, BIOS B9403CVAR.311 12/24/2024
> Call Trace:
>  <TASK>
>  [...]
>  schedule_timeout+0xbd/0x100
>  __down_common+0x175/0x290
>  down_timeout+0x67/0x70
>  acpi_os_wait_semaphore+0x57/0x90
>  [...]
>  asus_wmi_evaluate_method3+0x87/0x190 [asus_wmi]
>  led_trigger_event+0x3f/0x60
>  [...]
Hi and thank you very much for this!

Reviewed-by: Denis Benato <benato.denis96@gmail.com>
> Fixes: 9fe44fc98ce4 ("platform/x86: asus-wmi: Simplify the keyboard brightness updating process")
> Signed-off-by: Anton Khirnov <anton@khirnov.net>
> ---
> v2:
>  - reworded commit message, adding traceback
>  - merged lines in kbd_led_set() signature
> ---
>  drivers/platform/x86/asus-wmi.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
> index e72a2b5d158e..8e3300f5c294 100644
> --- a/drivers/platform/x86/asus-wmi.c
> +++ b/drivers/platform/x86/asus-wmi.c
> @@ -1619,14 +1619,14 @@ static void do_kbd_led_set(struct led_classdev *led_cdev, int value)
>  	kbd_led_update(asus);
>  }
>  
> -static void kbd_led_set(struct led_classdev *led_cdev,
> -			enum led_brightness value)
> +static int kbd_led_set(struct led_classdev *led_cdev, enum led_brightness value)
>  {
>  	/* Prevent disabling keyboard backlight on module unregister */
>  	if (led_cdev->flags & LED_UNREGISTERING)
> -		return;
> +		return 0;
>  
>  	do_kbd_led_set(led_cdev, value);
> +	return 0;
>  }
>  
>  static void kbd_led_set_by_kbd(struct asus_wmi *asus, enum led_brightness value)
> @@ -1802,7 +1802,7 @@ static int asus_wmi_led_init(struct asus_wmi *asus)
>  		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_set_blocking = kbd_led_set;
>  		asus->kbd_led.brightness_get = kbd_led_get;
>  		asus->kbd_led.max_brightness = 3;
>