Arch Linux

SpeedGhost

Member

Registered: 2014-04-17

Posts: 10

[SOLVED] ASUS backlight

I have an ASUS N550JV laptop.  Wiki page is listed here:

The previous solution for getting display backlight controls to work using the Function keys was to add the kernel parameter

acpi_osi=

After updating to Kernal 3.18.2-2-ARCH this no longer works.  Downgrading back to any 3.17 kernel fixes the issue.  Anyone else having this same issue or have any ideas on how to fix this with the new kernel?

Last edited by SpeedGhost (2015-01-28 17:35:17)

whitetimer

Member

Registered: 2010-05-23

Posts: 207

Re: [SOLVED] ASUS backlight

Got the same problem too

Head_on_a_Stick

Member

From: The Wirral

Registered: 2014-02-20

Posts: 8,824

Website

Re: [SOLVED] ASUS backlight

Here are the kernel parameters for 3.18:
http://lxr.free-electrons.com/source/Do … meters.txt

Have you tried:

acpi_backlight=vendor

Or:

acpi_backlight=video

---

Jin, Jîyan, Azadî

TheSaint

Member

From: my computer

Registered: 2007-08-19

Posts: 1,532

Re: [SOLVED] ASUS backlight

HoaS,
They had a working solution with acpi_osi=, but seem that has currently changed.
My  Asus was same, but no effect to dim the backlight, so I didn't set it. I use different hotkeys to adjust backlight.

---

do it good first, it will be faster than do it twice the saint

SpeedGhost

Member

Registered: 2014-04-17

Posts: 10

Re: [SOLVED] ASUS backlight

Head_on_a_Stick

Thanks for the resource.  Yes, I had tried both

acpi_backlight=vendor

and

acpi_backlight=video

I'm looking into the various other acpi_osi options but given what leaving the option blank does for acpi_osi= I don't think other options there will help much.

TheSaint

Member

From: my computer

Registered: 2007-08-19

Posts: 1,532

Re: [SOLVED] ASUS backlight

What's your DE ?
Have you tried with xev and/or showkeys, to see if your hotkeys are detected ?
Have you tried with

$ xbacklight - 10%
$ xbacklight + 10%

---

do it good first, it will be faster than do it twice the saint

SpeedGhost

Member

Registered: 2014-04-17

Posts: 10

Re: [SOLVED] ASUS backlight

TheSaint,

Primary DE on this laptop is GNOME 3.  xev registers most fn+function keys just not the backlight ones on F5 and F6.  Will try showkeys later to see if anything changes.
xbacklight commands work just fine and the slider in GNOME Settings works fine as long as acpi_osi= is still listed as a kernel parameter.

TheSaint

Member

From: my computer

Registered: 2007-08-19

Posts: 1,532

Re: [SOLVED] ASUS backlight

So, we may summarize that only hotkeys are missing.
The backlight are managed by Xorg.
So some check

$ ls ls /sys/class/backlight/
$ lspci -vnn |grep VGA

Also worth to see here. In particular something around xorg.conf.
I'd tell you that keys maybe seen, but they could point in a wrong place. xrog.conf has an option for that.

EDIT
And what did you about this ?

Last edited by TheSaint (2015-01-17 01:53:56)

---

do it good first, it will be faster than do it twice the saint

Inerla

Member

Registered: 2015-01-17

Posts: 2

Re: [SOLVED] ASUS backlight

Hello,

I have an other Asus laptop (PU301), and before the kernel update to the 3.18, F5 and F6 touches work fine if I add parameters " acpi_osi= acpi_backlight=intel" in the grub.cfg file.
With the udpate, I'm in the same situation than several of you.

In several environment (awesome, KDE), the multimedia keys F5 and F6 didn't work, but xbacklight works.

I write the journalctl -f command when I press theses touches (for the F5 key), in order to find any suggestion :

ACPI Error: Method parse/execution failed [\_SB_.PCI0.GFX0.GCBL] (Node ffff880118080370), AE_AML_UNINITIALIZED_ELEMENT (20140926/psparse-536)
ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_.SBRN] (Node ffff8801194487f8), AE_AML_UNINITIALIZED_ELEMENT (20140926/psparse-536)
ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPCB.EC0_._Q0E] (Node ffff880119448820), AE_AML_UNINITIALIZED_ELEMENT (20140926/psparse-536)

ls /sys/class/backlight/intel_backlight
actual_brightness  bl_power  brightness  device  max_brightness  power  subsystem  type  uevent

Best regards

TheSaint

Member

From: my computer

Registered: 2007-08-19

Posts: 1,532

Re: [SOLVED] ASUS backlight

I write the journalctl -f command when I press theses touches (for the F5 key), in order to find any suggestion

Did you that in a VT or console ?
I tried in konsole, but it doesn't show anything.

---

do it good first, it will be faster than do it twice the saint

Inerla

Member

Registered: 2015-01-17

Posts: 2

Re: [SOLVED] ASUS backlight

In xterm or konsole : same report (awesome and kde).

SpeedGhost

Member

Registered: 2014-04-17

Posts: 10

Re: [SOLVED] ASUS backlight

Here's the output of the following as requested

$ ls /sys/class/backlight/
intel_backlight@
$ lspci -vnn | grep VGA
00:02.0 VGA compatible controller [0300]: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA controller])

I have always had acpi_osi= as a kernel parameter as without it, even xbacklight commands don't work.  Still looking manually configuring the hotkeys, but would prefer to find the real cause of the change.

TheSaint

Member

From: my computer

Registered: 2007-08-19

Posts: 1,532

Re: [SOLVED] ASUS backlight

Did you try as Inerla did, putting the arguments in the command line ?
Is your hardware a dual video card ?
xbacklight follow the configuration in xorg.conf. So probably you should put

Option     "registryDwords" "EnableBrightnessControl=1"

as of nvidia proprietary drivers.
For intel should be

Opiton "Backlight" "intel_backlight"

Both in the Section "Screen".
The you may try manually to see if manually you can modify the brightness by

$ mbght=$(cat /sys/class/backlight/intel_backlight/brightness) \
echo $(($mbght / 2)) > sudo tee /sys/class/backlight/intel_backlight/brightness

This would halve the brightness.
More details at the wiki

Last edited by TheSaint (2015-01-27 21:22:20)

---

do it good first, it will be faster than do it twice the saint

weaner

Member

Registered: 2006-04-03

Posts: 11

Re: [SOLVED] ASUS backlight

Seems to be working for me again with the latest kernel upgrade.

SpeedGhost

Member

Registered: 2014-04-17

Posts: 10

Re: [SOLVED] ASUS backlight

Yes, I went out of town for the week and came back to find that the new kernel revision 3.18.4 had fixed it.  if i execute

ls /sys/class/backlight

I now get

acpi_video0@  acpi_video1@  intel_backlight@

Still going to try and look into what the change was that caused it since it seems to have also affected hooking up an external display.  This laptop is dual video with Nvidia and Intel, but I have turned the nvidia off and never use it.
For now I will go ahead and mark this thread as solved.