Re: [PATCH v3 5/7] platform/x86: thinkpad_acpi: Skip LED suspend/resume on auto-mode machines

["Mark Pearson" <mpearson-lenovo@squebb.ca>]

On Sat, Nov 14, 2026, at 12:48 PM, Qiling Zhu wrote:
> On machines whose EC supports the auto mode (MLCG bit 20) the firmware
> takes care of the keyboard backlight across suspend by itself: on a
> ThinkPad X1 Carbon Gen 14 it turns the backlight off on suspend and
> restores the previous level on resume for the manual levels, and keeps
> auto mode across suspend; after hibernation from auto mode the
> backlight comes back off.
>
> Skip led_classdev_suspend() and led_classdev_resume() entirely on those
> machines: the LED core no longer enters the suspended state, which also
> removes the window in which userspace writes and pending
> set_brightness work would race against a suspended LED.
>
> Machines without auto-mode support keep the existing behavior.
>
> Signed-off-by: Qiling Zhu <kmatzkaczor244@gmail.com>
> ---
>  drivers/platform/x86/lenovo/thinkpad_acpi.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c 
> b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> index 681b340a1..f9e2d324d 100644
> --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
> +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> @@ -5317,6 +5317,14 @@ static void kbdlight_suspend(void)
>  	if (!tp_features.kbdlight)
>  		return;
> 
> +	/*
> +	 * On machines with auto-mode support the firmware takes care of
> +	 * the keyboard backlight across suspend by itself; keep the LED
> +	 * core out of it.
> +	 */
> +	if (tp_features.kbdlight_auto)
> +		return;
> +
>  	led_cdev = &tpacpi_led_kbdlight.led_classdev;
>  	led_update_brightness(led_cdev);
>  	led_classdev_suspend(led_cdev);
> @@ -5327,6 +5335,9 @@ static void kbdlight_resume(void)
>  	if (!tp_features.kbdlight)
>  		return;
> 
> +	if (tp_features.kbdlight_auto)
> +		return;
> +
>  	led_classdev_resume(&tpacpi_led_kbdlight.led_classdev);
>  }
> 
> -- 
> 2.56.1
Looks good to me.
Reviewed-by: Mark Pearson <mpearson-lenovo@squebb.ca>
Mark