lcd not going backlight off

[lists.x.org at bertrand.hudzia.net]

Hello,

I got a laptop Asus Zephyrus Duo with two integrated lcd.

Under Xorg the main one is called eDP-1-1 and the second is DP-1-1.

When reaching idle timeout, Xorg turn off all monitor except the DP-1-1.

I've found this for the working one :

echo 1 > 
/sys/devices/pci0000:00/0000:00:02.0/drm/card1/card1-eDP-1/intel_backlight/bl_power


But it doesn't exist for the DP-1-1. It may be the reason why it stay on :/

As far as I know, the two lcd are connected to the same intel integrated 
graphic.

What logs can I give you to help me ?

Have a nice day,

     Bert.