Arch Linux

Super-Nathan

Member

Registered: 2012-05-19

Posts: 23

Website

[solved] backlight adjustment and resume problems

problem:
1) Backlight does not adjust all the up or down using the Fn keys, the Fn keys do effect a change but they cannot achieve all-the-way bright or all-the-way off.

2) Backlight does not adjust at all with Fn keys after resume.

Hardware:
Toshiba Prtege Z930

Software:
3.9.4-1-ARCH
Gnome 3.8
GDM
syslinux

What I have tried:
I have tried booting with the parameters: acpi_backlight=vendor and acpi_backlight=legacy. I Must use acpi_backlight=vendor in order to get the Fn keys to work before resume.

I have tried booting with the parameters: acpi_osi="!Windows 2012" , acpi_osi=\"!Windows 2012\" , acpi_osi=Linux. These parameters do nothing.

What I also know:
I can change the brightness at any time from the command line using: echo $NUMBER > /sys/class/backlight/intel_backlight/brightness

I also know this works on a Debian install (kernel 3.9.4) with only the kernel parameter acpi_backlight=vendor

Last edited by Super-Nathan (2013-06-03 07:50:59)

Super-Nathan

Member

Registered: 2012-05-19

Posts: 23

Website

Re: [solved] backlight adjustment and resume problems

solution (like a mother fucking ninja)

After hours of googling I found the solution at the end (and its long) of this Debian bug report.

long story short, if you followed the Arch Wiki for an Intel graphics card like this computer has you would have a /etc/X11/xorg.conf.d/20-intel.conf that looks like this:

Section "Device"
   Identifier  "Intel Graphics"
   Driver      "intel"
   Option      "AccelMethod"  "sna"
EndSection

You have to change that to:

Section "Device"
        Identifier  "Intel Graphics"
        Driver      "intel"
        Option      "AccelMethod"  "sna"
        Option     "Backlight"          "intel_backlight"
        Driver      "intel"
        BusID       "PCI:0:2:0"

EndSection

this forces the backlight to associate with the correct device.

Xyne

Administrator/PM

Registered: 2008-08-03

Posts: 6,965

Website

Re: [solved] backlight adjustment and resume problems

solution (like a mother fucking ninja)

Please use those ninja skills to update the wiki with the solution so aspiring grasshoppers may learn from your wisdom.

---

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Super-Nathan

Member

Registered: 2012-05-19

Posts: 23

Website

Re: [solved] backlight adjustment and resume problems

solution (like a mother fucking ninja)

Please use those ninja skills to update the wiki with the solution so aspiring grasshoppers may learn from your wisdom.

Done, but I am poor wiki-er, and would appreciate some edditing/proofreading:
https://wiki.archlinux.org/index.php/Intel_Graphics

joetw

Member

Registered: 2012-11-22

Posts: 5

Re: [solved] backlight adjustment and resume problems

Done, but I am poor wiki-er, and would appreciate some edditing/proofreading:
https://wiki.archlinux.org/index.php/Intel_Graphics

Thanks. Duplicate Driver lines in both code blocks. Does one need lspci or sth. to determine BusID? Typos: accerleration, creat. Alignment of backlight lines.

Super-Nathan

Member

Registered: 2012-05-19

Posts: 23

Website

Re: [solved] backlight adjustment and resume problems

Done, but I am poor wiki-er, and would appreciate some edditing/proofreading:
https://wiki.archlinux.org/index.php/Intel_Graphics

Thanks. Duplicate Driver lines in both code blocks. Does one need lspci or sth. to determine BusID? Typos: accerleration, creat. Alignment of backlight lines.

Dude, it's a wiki. Why didn't you just edit it?