"Fn" key not recognized to change the screen brightness on Dell laptop.

[M]

Hi,

I sent a post to the Freebsd forum as I was looking for help to control the
screen brightness on my laptop( dell latitude 7240 with an Haswell cpu).
Mate Desktop is installed.

I have been redirected to this mailing list to see if you can eventually
help me.

My goal is to get the “fn” key working to change the screen brightness.

I installed https://www.freshports.org/graphics/intel-backlight and I can
change the screen brightness by entering ,for.e.g, “intel_backlight=40”.

It works as well by doing “ hw.acpi.video.lcd0.brightness=40”.

I followed the instructions in this post
http://www.daemonology.net/blog/2020-05-22-my-new-FreeBSD-laptop-Dell-7390.html
where
the author Colin Percival said:











*“I want to be able to control the brightness of the screen (aka. the
backlight connected to the Intel video chipset): # pkg install
intel-backlight and in particular to be able to control it via the function
keys (Fn+Up, Fn+Down) which Dell exposes via ACPI: # echo
'acpi_video_load="YES"' >> /boot/loader.conf # cp
/usr/local/share/examples/intel-backlight/acpi-video-intel-backlight.conf \
/usr/local/etc/devd/* “

The keys associated for the screen brightness are the “Fn” and the top
arrow to increase the brightness and the down arrow to decrease.

The problem is when I press the “fn” key with one of those keys, nothing
happens but I can see the screen very slightly flashing but there is no
light increased or decreased.

*Please note the “fn” key is working fine if I want to change the keyboard
backlight by pressing “fn” and the right arrow .*

How can I use the “fn” key to modify the screen brightness ?



I added a few files if that can help


dmesg    https://termbin.com/f7xh
pciconf   https://termbin.com/oajp
kldstat    https://termbin.com/98jr
rc.conf    https://termbin.com/o397



Thank your for your time and help!