Arch Linux

magum

Member

Registered: 2011-08-22

Posts: 22

[SOLVED] Brightness keeps changing: upowerd?

Hi,

My current system keeps changing the brightness on a number of system events:
- wake-up from suspend
- power cable inserted
- power cable removed

So every time I keep changing my brightness back to a usable level.

There is some activity in upowerd, so I assume upowerd is either responsible or used by some other system component.

Can you tell me where and how I can change this behavior?

-- Niklas

Last edited by magum (2014-07-30 10:53:51)

Head_on_a_Stick

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From: London

Registered: 2014-02-20

Posts: 7,732

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Re: [SOLVED] Brightness keeps changing: upowerd?

What desktop environment are you using?
These are usually options controlled by the power-manager application...

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magum

Member

Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

I am using qtile. It doesn't come with a power manager application like for xfce4/gnome/kde.

Head_on_a_Stick

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From: London

Registered: 2014-02-20

Posts: 7,732

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Re: [SOLVED] Brightness keeps changing: upowerd?

Have a look at /etc/systemd/logind.conf; there is also /etc/UPower/UPower.conf but I think this is deprecated in favour of the systemd file...

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magum

Member

Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

Hi Head_on_a_Stick,

thanks for your answer.

I checked the files you mentioned. There are a number of options there, but nothing about brightness reduction due to suspend/opening lid/closing lid etc. It looks like I am looking in the wrong place.

Head_on_a_Stick

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From: London

Registered: 2014-02-20

Posts: 7,732

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Re: [SOLVED] Brightness keeps changing: upowerd?

Yeah, sorry didn't read your question properly: my apologies
EDIT: you could try removing upower...

Last edited by Head_on_a_Stick (2014-06-02 17:05:02)

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magum

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Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

Yeah I think, that might be a good way to go. Still I am wondering, Arch should have at least a place where the default brightness is defined? Or might this be completely up to the BIOS?

Name Taken

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Registered: 2014-04-09

Posts: 113

Re: [SOLVED] Brightness keeps changing: upowerd?

You can also set a cron job to automatically reset your brightness every minute.

Head_on_a_Stick

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From: London

Registered: 2014-02-20

Posts: 7,732

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Re: [SOLVED] Brightness keeps changing: upowerd?

Yeah I think, that might be a good way to go. Still I am wondering, Arch should have at least a place where the default brightness is defined? Or might this be completely up to the BIOS?

Systemd has a backlight.service, but it just saves the level at the end of a session & then reloads it when you boot up...
It could be a conflict between (the deprecated) upower & systemd; but I'm not exactly an expert, sorry (n00b-alert!)

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orschiro

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Registered: 2009-06-04

Posts: 2,136

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Re: [SOLVED] Brightness keeps changing: upowerd?

Relight could help you: https://bbs.archlinux.org/viewtopic.php?id=156597

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@orschiro

magum

Member

Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

So here's what I did:
Disable Upowerd by moving the config out of  /etc/dbus-1/system.d & restart
=> On the events mentioned, the brightness still get's updated, but to a different--much more acceptable--level.

So let's be sure:
Activate Upowerd again, by moving config back & restart
=> The brightness is still on the same acceptable level.

Yay, problem solved! Or is it?
Some hours later, my brightness was again updated to darkness on any of the events. -.-'

So I assume that somewhere under the hood, there is an "update-brightness" that is used for any of the events mentioned. And somewhere else there is a "mysterious process" changing the "update-brightness" on some events (possibly on low battery power).

At this point I have no idea where either "update-brightness" or "mysterious process" are, but I would assume that it is related to systemd. (The developer of my WM, qtile made it clear that they are not changing the levels. The BIOS also does not have any configurable brightness option.)

If you have any hints on "update-brightness" or "mysterious process", I would be happy to try them .

@Name Taken: Yeah hacking the thing would be a possiblity. Not my favourite, though. It s-h-o-u-l-d be so simple.

EDIT: So it's definitely independent of UPowerd. And it is not related with low battery levels.

Last edited by magum (2014-06-05 10:39:58)

magum

Member

Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

Still have the same issue. Only I noticed external screens are not affected.

magum

Member

Registered: 2011-08-22

Posts: 22

Re: [SOLVED] Brightness keeps changing: upowerd?

I solved the issue.

As long as I changed the brightness by writing to /sys/class/backlight/intel_backlight/brightness it would change back every time. How ever, now I changed the backlight with xbacklight which uses XCB and suddenly I have no problem anymore.

The reasons remain a mistery for me, but the effect is real .