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psycho

Member

Registered: 2013-04-26

Posts: 29

[Solved] No backlight on Sony Vaio

Hello,

I am using a Sony Vaio (VPCEJ-1M1E) laptop, and the backlight can't be modified.

~ » uname -r
3.10.3-1-ARCH
~ » sudo cat /sys/class/backlight/acpi_video0/brightness 
[sudo] password for psycho: 
15
~ » sudo echo 5 > /sys/class/backlight/acpi_video0/brightness                                                                                                                                                                    
zsh: permission denied: /sys/class/backlight/acpi_video0/brightness
~ » su
Password: 
[root@madness psycho]# echo 5 > /sys/class/backlight/acpi_video0/brightness  # brightness haven't changed
[root@madness psycho]# cat /sys/class/backlight/acpi_video0/brightness 
5
[root@madness psycho]# cat /sys/class/backlight/acpi_video0/actual_brightness 
5
[root@madness psycho]# echo 5 > /sys/class/backlight/acpi_video0/actual_brightness
bash: /sys/class/backlight/acpi_video0/actual_brightness: Permission denied
[root@madness psycho]# 

I have read about using acpi_osi=Linux and acpi_backlight=vendor on the kernel line. Without either of them, there's no acpi_video0 in /sys/class/backlight. With both of them, there's still no acpi_video0, yet it appears when using only 'acpi_osi=Linux'. Even so, i can't set the brightness.

Any other things i should try ?

Thanks in advance,
psycho.

Last edited by psycho (2013-08-02 07:08:59)

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~ > fortune
I never met a piece of chocolate I didn't like.

cfr

Member

From: Cymru

Registered: 2011-11-27

Posts: 7,178

Re: [Solved] No backlight on Sony Vaio

What graphics card do you have? Which driver are you using (if using X)?

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psycho

Member

Registered: 2013-04-26

Posts: 29

Re: [Solved] No backlight on Sony Vaio

What graphics card do you have? Which driver are you using (if using X)?

Graphics card : Nvidia 410M
Using proprietary driver :

~ » pacman -Qs nvidia
local/lib32-nvidia-libgl 319.32-1
    NVIDIA drivers libraries symlinks (32-bit)
local/lib32-nvidia-utils 319.32-1
    NVIDIA drivers utilities (32-bit)
local/libcl 1.1-3
    OpenCL library and ICD loader from NVIDIA
local/libvdpau 0.6-2
    Nvidia VDPAU library
local/nvidia 319.32-4
    NVIDIA drivers for linux
local/nvidia-libgl 319.32-1
    NVIDIA drivers libraries symlinks
local/nvidia-utils 319.32-1
    NVIDIA drivers utilities

Edit : switched to nouveau instead of  nvidia drivers, put both acpi_osi=Linux and acpi_backlight=vendor into kernel boot line, and can successfully modify backlight.

Last edited by psycho (2013-08-02 07:08:46)

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~ > fortune
I never met a piece of chocolate I didn't like.