You are not logged in.

#1 2013-10-12 06:55:18

beanaroo
Member
Registered: 2013-03-05
Posts: 39

[SOLVED] Systemd forcing laptop brightness down to zero.

Can somebody please, pretty please, explain to me how I can tell systemd to STOP turning off my laptop brightness half-way during boot?

Started Load/Save Screen Backlight Brightness of acpi_video0.

Turns brightness down to zero. According to the man page:

systemd-backlight@.service is a service that restores the display backlight brightness at early-boot and saves it at shutdown. On disk, the backlight brightness is stored in /var/lib/backlight/.

On my Arch it is actually in /var/lib/systemd/backlight/acpi0. I tried modifying the value to anything between 1 and 100 but it the file is reset to 0 every boot, maybe this is normal.

I also tried to disable the damn systemd-backlight service but it re-enables itself every boot too.

Please can somebody help me, I'm pulling my hair out. I have tried various kernel parameters and acpi_backlight=vendor works but forces brightness to 100% and I can't change it. (unless of course if I force /sys/class/... which is not a solution)

Last edited by beanaroo (2013-10-12 07:30:49)

Offline

#2 2013-10-12 07:30:32

beanaroo
Member
Registered: 2013-03-05
Posts: 39

Re: [SOLVED] Systemd forcing laptop brightness down to zero.

Alexander Diana graciously helped me via Google+ community.

There is a mask function to prevent services from being loaded automatically and manually.

$ sudo systemctl mask systemd-backlight@acpi_video0.service

Offline

#3 2013-10-16 02:24:53

cfr
Member
From: Cymru
Registered: 2011-11-27
Posts: 7,143

Re: [SOLVED] Systemd forcing laptop brightness down to zero.

It definitely isn't normal for it to keep going to 0. Mine currently has the value 12 in it. (My file is /var/lib/systemd/backlight/acpi_video0.) I'm not sure if it makes a difference that I have laptop-mode-tools managing the backlight, though. But I don't see it go to 0 at any point during boot.

That is, unless something somewhere is configuring it this way, this sounds like a bug and the solution you're using a work around. Not suggesting you shouldn't use it, of course, but maybe worth reporting, too?

Last edited by cfr (2013-10-16 02:25:51)


CLI Paste | How To Ask Questions

Arch Linux | x86_64 | GPT | EFI boot | refind | stub loader | systemd | LVM2 on LUKS
Lenovo x270 | Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz | Intel Wireless 8265/8275 | US keyboard w/ Euro | 512G NVMe INTEL SSDPEKKF512G7L

Offline

Board footer

Powered by FluxBB