Screen Brightness problem linux mint 13 samsung n145

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Screen Brightness problem linux mint 13 samsung n145

Postby alloykick on Mon Mar 25, 2013 12:52 am

My problem is I have installed Linux Mint 13 Maya Cinnamon 64bit on a Samsung N145p netbook. The operating system works apart from the fact I have a serious brightness issue with the screen.

When the power cable is attached the screen always resets itself to a glaringly bright maximum brightness setting every time I start, even if I reduce the brightness in the settings or with the function up/down brightness keys in the previous session.

When the computer is on battery power the screen brightness is very dim and almost impossible to use in daylight. The brightness function keys indicate that the setting is at max, yet this is not true and I cannot increase the brightness. Restarting it will stay at the same dimness.

I have looked for two days trying to fix this, if I can't I won't be able to use linux,as it is making it practically unusable. My dual boot windows 7 installation does not have this problem.
Please help?
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby slay3r on Mon Mar 25, 2013 5:58 am

I had a very similar issue trying to control the brightness

Try to run this command in your terminal
Code: Select all
$ ls /sys/class/backlight/*

if you have two directories in there one of them is gnome specific with the max and min varying between (0-7) while the other one is vendor specific and varies from (0-4000+)
Code: Select all
cd/sys/class/backlight/acpi_video0
cat max_brightness
cat actual_brightness
echo 7 | sudo tee brightness

Feel free to modify the brightness according to the need from maximum and minimum defined. This one did help me resolve my issue, I hope it does the same for you.

P.S: I have no access to a linux box at work. Please bare with my vague numbers.
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby alloykick on Mon Mar 25, 2013 3:33 pm

Hi, thanks for the reply,
however i'm not able to get this working. This is what i get when I type :

ls /sys/class/backlight/*

actual_brightness device subsystem
bl_power max_brightness type
brightness power uevent

Then when i type
cd /sys/class/backlight/acpi_video0

bash: cd: /sys/class/backlight/acpi_video0: No such file or directory

You said if " have two directories in there one of them is gnome specific with the max and min varying between (0-7) while the other one is vendor specific and varies from (0-4000+) ". How do I know which is gnome specific and which is vendor specific??
I am unclear as what to type now and where?
If i type

ls /sys/class/backlight/ without the * at the end I get:
intel_backlight

So now I try:
cd /sys/class/backlight/intel_backlight
cat max_brightness
returns the value
12421

cat actual_brightness
returns the value
12421

where can I try and edit and save the new values for these numbers?

and if i type :
echo 7 | sudo tee brightness
the screen goes black and i have to press function +up brightness key to make the screen get back to its very dim setting again.?
Thanks
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby slay3r on Mon Mar 25, 2013 11:15 pm

Please don't fiddle with the intel_backlight as it is in its max value
if not please set the value in max_brightness to actual_brightness

The screen went black when you executed this
Code: Select all
echo 7 | sudo tee brightness

because the value is too low for your display. Please play with the numbers and you will arrive at a number which is suitable for your display.

Usually the maximum and the current values are displayed in the
Code: Select all
cat /sys/class/backlight/max_brightness
cat /sys/class/backlight/actual_brightness


one has to set a value of the brightness between the actual and the maximum values
Code: Select all
echo <<desired_brightness_number>> | sudo tee brightness


I hope this helps with your issue.

P.S : the difference in the folder structure is because i run a laptop from a different vendor
sorry for the confusion :)
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby alloykick on Tue Mar 26, 2013 12:57 am

thanks for the reply,

I have nowhere else to try and set values other than in the intel_backlight as it is the only folder in the backlight. It is not clear even then as to where and how I would make and change these values, how is this done?

You mention I should try and set a value some where between be actual and maximum but these are both the same so that is impossible,they are both 12421??

if i type
echo 12421 | sudo tee brightness
then all I get is the same dim screen brightness.

this doesn't seem to make any difference whatsoever??
I'm still stuck with a dismally dim linux mint screen.
help!
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby exit885 on Tue Mar 26, 2013 7:13 am

This is the solution, I have the same and it works great.
You must adding the voria ppa, https://launchpad.net/~voria/+archive/ppa
Then you look for samsung blacklight in synaptic.
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby alloykick on Tue Mar 26, 2013 6:12 pm

Thanks for your information,
You must adding the voria ppa, https://launchpad.net/~voria/+archive/ppa


From looking around there I found this code and typed:

Code: Select all
sudo add-apt-repository ppa:voria/ppa
sudo apt-get update
sudo apt-get install samsung-tools samsung-backlight


Then in terminal I typed this to see if the samsung backlight folder was there now:
Code: Select all
ls /sys/class/backlight/


this showed 2 folders :

intel_backlight samsung

now i typed:
Code: Select all
cd /sys/class/backlight/samsung
cat actual_brightness
cat max_brightness

This gave me a value of 8 for max_brightness and 5 for actual_brightness.

This enabled me to get control of the brightness and meant that my actual and maximum values weren't the same, I can now increase my brightness when running off the battery.

However upon restarting or turning off the dim screen would return if on battery power and maximum brightness would return if power cable is plugged in, although at least I could adjust them. I wanted the screen brightness to remember the setting everytime the computer is turned on.

I found the following on another linux mint thread :
You can change screen brightness in the Screen settings dialog, but it won't be persistent, you must repeat it every time your boot up your laptop. This has bugged many users so thanks to esteban for pointing to a relatively easy fix.

First you have to find out what the "max_brightness" is on your system. Navigate to "/sys/class/backlight/" and in a relevant subfolder (mine is named "acpi_video0") find the "max_brightness" file and make a note of the number in it, mine was "15", esteban's was "976", yours may be a third number - this is the numerical value of your maximum brightness setting. Then create a start-up script to reduce brightness:

Code: Select all
gedit ~/.lowerbrightness.sh



... and paste this into the opened empty document
Code: Select all
 #!/bin/sh
    #change brightness setting on startup or resume
    pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 8



... BUT! change the the last digit to a number relevant to you. I've put "--set-brightness 8" to get a ca. 50% brightness setting (my max_brightness value was 15); esteban put "--set-brightness 488" to achieve the same on his laptop (his max_brightness value was 976). If you want e.g. 75% screen brightness, set the number to 3/4 of your max_brightness number (only give whole numbers, no "324,5"!). You get the idea. That done, save and exit. Right-click on your newly created ".lowerbrightness.sh" file (it may be hidden, press CTRL+H to see it in your home directory), select Properties and in the Permissions tab make the file executable with a tick in "Allow executing file as program" - this is important or it won't work. Lastly, run the following command (replace USERNAME with your user name):

Code: Select all
gsettings set org.gnome.settings-daemon.peripherals.input-devices hotplug-command "/home/USERNAME/.lowerbrightness.sh"


And that's it, persistent brightness setting.


And now at last linux Mint and my samsung n145 are in sync with the brightness settings, also now when the computer is turned on and off the brightness setting is remembered whether plugged in or running off the battery, no more dim screen or maximum glaring brightness!

Thanks everyone again for your help. :D
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Re: Screen Brightness problem linux mint 13 samsung n145

Postby derek0199 on Mon May 27, 2013 9:35 am

I am having the same trouble with my Samsung laptop R 700 only more so the screen is too dark even if I use the Fn key And and the up arrow to increase the brightness the screen stays dark and this is even when plugged into the mains power, I hope someone can help with this as I will not be able to use what otherwise looks to be an excellent system thank you in advance for any suggestions

From Derek
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