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#1 2018-05-01 22:43:24

GNUser
Member
Registered: 2017-03-16
Posts: 317

closing and opening laptop lid maximizes brightness [SOLVED]

Since graphics and laptop lid have given me such a headache in Ascii, I want to learn more about these things.

I have a T400 with integrated Intel grapics, libreboot, MATE, and lightdm. In my Devuan Jessie partition, which is quite a vanilla installation using the default kernel (version 3.16.51-3+deb8u1), I've noticed that if I turn the display brightness down, close laptop lid, then open laptop lid, brightness automatically changes itself to maximum. How can I prevent this?

Some details:
-acpi is not installed
-I have IgnoreLid=true in /etc/UPower/Upower.conf
-using i915.panel_ignore_lid=1 and i915.panel_ignore_lid=-2 kernel boot options have no effect

Last edited by GNUser (2018-05-02 20:20:16)

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#2 2018-05-01 22:54:45

devuser
Member
Registered: 2018-04-30
Posts: 34

Re: closing and opening laptop lid maximizes brightness [SOLVED]

Any reason for not having acpi? Otherwise i'd try if acpi_listen shows some event relating to lid opening/closing. If there are events binding scripts that either save or restore brightness might work. At least this technique brought my speaker/microphone mute buttons to life by binding amixer one liners.

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#3 2018-05-01 23:04:35

GNUser
Member
Registered: 2017-03-16
Posts: 317

Re: closing and opening laptop lid maximizes brightness [SOLVED]

I never needed acpi in my Jessie installation, so never installed it. acpi_listen command is not present.

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#4 2018-05-01 23:37:49

devuser
Member
Registered: 2018-04-30
Posts: 34

Re: closing and opening laptop lid maximizes brightness [SOLVED]

acpi_listen is part of acpid package.

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#5 2018-05-01 23:58:06

GNUser
Member
Registered: 2017-03-16
Posts: 317

Re: closing and opening laptop lid maximizes brightness [SOLVED]

I see. Well, in my Jessie install I don't have acpi, acpid, or any packages installed which contain the string 'acpi' anywhere in the package name.

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#6 2018-05-02 00:15:26

devuser
Member
Registered: 2018-04-30
Posts: 34

Re: closing and opening laptop lid maximizes brightness [SOLVED]

Well apt-get could always change that wink http://www.thinkwiki.org/wiki/How_to_co … _lid_close suggests the lid actually has an event. Well at least for closing it seems. If you could figure out how to save the brightness value from /sys/class/backlight and restore on open you'd be golden i'd say.

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#7 2018-05-02 17:14:28

GNUser
Member
Registered: 2017-03-16
Posts: 317

Re: closing and opening laptop lid maximizes brightness [SOLVED]

So I installed acpid and both closing the lid and opening it are events that acpi can catch. I save the brightness on lid close, then restore it on lid open. Now after I open the lid, the brightness is maxed out for a fraction of a second and then acpi restores the saved brightness.

So although I now have a workaround (thank you, devuser!), the main reason I opened the thread is that I would like to know what system component is cranking up the brightness when I open the lid. I know it's not UPower and not acpi (since it wasn't even installed). How do I find out if the culprit is X, the kernel, i915, or something else?

Last edited by GNUser (2018-05-02 17:21:06)

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#8 2018-05-02 19:47:20

devuser
Member
Registered: 2018-04-30
Posts: 34

Re: closing and opening laptop lid maximizes brightness [SOLVED]

GNUser wrote:

I would like to know what system component is cranking up the brightness when I open the lid.

Good question. Sadly i don't know but it seems it could also be the thinkpad-acpi kernel module (https://github.com/torvalds/linux/blob/ … d-acpi.txt). Didn't check but i wouldn't be suprised if that is even active before any actual acpi packages get installed. I am just guessing here but in my opinion it's either that or the i915 module as both include brightness controls or very maybe the BIOS but my bet would be on one of the first two.

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#9 2018-05-02 20:18:42

GNUser
Member
Registered: 2017-03-16
Posts: 317

Re: closing and opening laptop lid maximizes brightness [SOLVED]

My gut feeling is that it is a kernel component, too. Thanks for sharing your thoughts. I'm glad that my hunch seems plausible to at least one other knowledgeable user.

Maybe we'll never know for sure, but as long as we're not missing an obvious answer then I'm fine with that.

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