Brightness control on Dell
reddit / freebsd

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gnu-stallman · 2022-09-14 23:03

Hello BSD folks! I have installed FreeBSD this time as a desktop, but
I ran into issue that I cannot control backlight brightness with Fn
buttons. I am on Dell Latitude E7440 laptop. When I try to change
brightness it seems to do nothing, but in fact, if I lower brightness
from terminal, and try to lower again but using buttons, brightness
gets higher, and whateven button I press, brightness doesn't change.
Basically pressing buttons doesn't increase or decrease volume, it
just sets it to some value. Is there any workarounds, ways to disable
it or fix it?

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Get0utCl0wn · 2022-09-14 23:39

Try loading usbhid

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gnu-stallman · 2022-09-15 12:29

Okay, so after some time and research, I finally found solution. The
problem turned out to be in stock acpi_video in FreeBSD, causing LCD
brightness regulation button act strangely. There this
[repo](https://github.com/wime12/freelatitude) which has patched wmi
and acpi_video from this laptop. I had some issues with compilation in
FreeBSD 13, so fixed them and commited to this
[fork](https://github.com/istadem2077/freelatitude). One thing though,
kbdmxe makes keyboard unusable it Xorg. I personally don't need it,
luckily developer of original repo divided brightness control and
volume control, so that brightness is in DELL devd subsystem. What
about volume, I mapped it in openbox config to execute scripts from
`control-tools/`. Kbdxme only manages media and display management as
far as I understood. For me neither are fatal though. If you know how
to fix it, feel free. For brightness you don't need kbdmxe everything
other is necessary.