# question about power managment  acer timelineX [solved]

## -=GGW=- $ol!d $n4>|e

Hey all,

I just recently got a new laptop, acer aspire timelineX 3820T-6480...

Everything went extremeley well with setting up linux drivers etc... except power management.

For the life of me i can not get cpu frequency scaling nor lcd brightness to work.

I've followed the Gentoo Power Management guide (from the gentoo docs section)

Nothing seems to affect my cpu freq or lcd brightness, and my batterylife is melting away  :Sad: 

Any input is much apreciated

Thanks,

SolidusLast edited by -=GGW=- $ol!d $n4>|e on Wed Nov 16, 2011 9:39 am; edited 1 time in total

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## -=GGW=- $ol!d $n4>|e

GAH, i just spent 3 hours debugging this to no avail, power managment "appears" to be working, for example i have a 

/sys/class/backlight/acpi_video0/brightness

and it does get modified by my power management options when i plug or unplug my power cord. but no matter what the value of that file is, my screen is full bright. And i'm getting about 1/3 the battery life that i should be out of this laptop. Where the devil is the connection between these systems falling away? I double checked BIOS versions, i have version 1.19. The Acer timelineX is supposedly compatable with laptop-mode-tools since bios version 1.18... Any information on even how to debug this further is greatly appreciated.

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## chithanh

Does the computer have dual/switchable graphics or optimus? If so, it is possible that the discrete graphics was not properly turned off and ist still consuming power. That would also explain why the brightness control does not work, it is attempting to change the brightness on the wrong graphics chipset.

You may be able to remove power to the discrete chipset with the  /sys/kernel/debug/switcheroo/switch control.

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## -=GGW=- $ol!d $n4>|e

It doesnt have dual video, it does have intel HD integrated though, looking through that I found a fix that uses the kernel boot option acpi_osi=Linux That seems to allow me to manage my screen brightness via the keyboard functions, however I think my actual laptop_mode management is still debunked.

Sicne the acpi_osi change, although I can edit the brightness, It seems to have broken my systems ability to edit this brightness, (eg there is no longer communication between hardware and software. Is there a way i can confirm that cpufreq scaling etc is in fact working?

It seems to be silently failing on all accounts...

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## chithanh

You can check the file /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver whether acpi-cpufreq is managing your CPU.

Also it might help to upgrade to kernel 3.1 if you are not running it already. Besides you can try pcie.aspm=force kernel parameter if your BIOS does not let PCIe devices sleep properly.

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## -=GGW=- $ol!d $n4>|e

thanks! Turned out i had to manually set acpi_osi=Linux as a kernel param, I'm also a complete nub to acpi, (never owned a laptop in my life before now) and had the default set to performance. Switched it to ondemand and now i'm getting a nice 7.5 hours of life out of it assuming i suspend aiglx.

Hope this helps someone with similar issues. The kde power managment daemon currently has a bug that writes to the wrong file for screen brightness so although kde can tell when I have increased or decreased brightness it is hopeless to attempt to control these through their ui. Supposedly this is fixed in 4.7 I look forward to the day that becomes stable.

Cheers!

Solidus

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