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Old 03-10-2014, 11:55 AM   #1
rshepard
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Registered: Oct 2007
Location: Troutdale, Oregon
Distribution: Slackware
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Controlling Laptop Screen Brightness in Slackware-14.1/x86_64 with Xfce4


We have a Sony Vaio model PCG-61A14 and the screen brightness plugin does not work; the slider doesn't. It sits there. A few related threads here do not appear to be applicable; different distributions and hardware.

A couple of folks running Arch Linux suggested changing a sys file for screen brighness but I did not find apci_video when I looked for it.

Where in a Slackware system could I hard-set the brightness since the user has no control over this?

TIA,

Rich
 
Old 03-10-2014, 06:33 PM   #2
dunric
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It would help if you list what have you already tried.

You may try to pass following option combinations to kernel at boot

acpi_osi=Linux acpi_backlight=legacy
or
acpi_osi="!Windows 2012" acpi_backlight=legacy
or
acpi_osi=Linux acpi_backlight=vendor
or
acpi_osi="!Windows 2012" acpi_backlight=vendor

It did worked in similar situations many times.
 
Old 03-11-2014, 12:26 AM   #3
mfrias
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Registered: Dec 2007
Location: Cochabamba, Bolivia
Distribution: 574ckw4r3 14.0
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Quote:
Originally Posted by rshepard View Post
We have a Sony Vaio model PCG-61A14 and the screen brightness plugin does not work; the slider doesn't. It sits there. A few related threads here do not appear to be applicable; different distributions and hardware.
I also have sony vaio, but I loaded the kernel module "sony_laptop" to control function keys and other details. You should try load (as root):

Code:
modprobe sony_laptop
And again try to add the plugin. Don't forget "Brightness is controlled by vendor-specified hotkey or by the OS(ACPI or graphic driver)"

Quote:
Originally Posted by rshepard View Post
A couple of folks running Arch Linux suggested changing a sys file for screen brighness but I did not find apci_video when I looked for it.
It's another option. XFCE4 in Slackware 14.0 still doesn't keep the brightness level when the laptop is power off, so I create a rule in rc.local file to adjust the brightness when power on. Try running this in the console (as root):

get max brightness of acpi_video0 (first video card):
Code:
# cat /sys/class/backlight/acpi_video0/max_brightness
15
set value of brightness to 1st video card (acpi_video0):
Code:
# echo n > /sys/class/backlight/acpi_video0/brightness
Where "n" is a value between 0 to 15 (max brightness), n=7 is a good start. If you have a 2nd video card again repeat and changing "acpi_video0" to "acpi_video1". When you have the optimal value write it in the rc.local file (in my case):

Code:
# Set Brightness:
echo 7 > /sys/class/backlight/acpi_video0/brightness
echo 7 > /sys/class/backlight/acpi_video1/brightness
And enjoy!
 
Old 03-11-2014, 04:02 AM   #4
Perceptor
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Registered: Jul 2007
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Which Slackware version you are using? On my vaio I had to install the proprietary video drivers to control brightness with 14.0; on 14.1 everything worked out of the box.

Edit: sorry, saw the title. I think installing the proprietary driver should work.

Last edited by Perceptor; 03-11-2014 at 04:05 AM.
 
Old 03-11-2014, 03:22 PM   #5
rshepard
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Registered: Oct 2007
Location: Troutdale, Oregon
Distribution: Slackware
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I added acpi_osi=Linux acpi_backlight=legacy to lilo.conf'd Append line and it appears to work. At least, the slider on the widget moves up and down.

This is on Slackware-14.1/x86_64.

Thanks, all,

Rich
 
  


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