Samsung NP300V5A-S0CIN brightness issue.

[ttsdinesh]

This is the o/p

dinesh@dinesh-lt:~$ grep . /sys/class/backlight/*/*
/sys/class/backlight/acpi_video0/actual_brightness:7
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:7
grep: /sys/class/backlight/acpi_video0/device: Is a directory
/sys/class/backlight/acpi_video0/max_brightness:7
grep: /sys/class/backlight/acpi_video0/power: Is a directory
grep: /sys/class/backlight/acpi_video0/subsystem: Is a directory
/sys/class/backlight/acpi_video0/type:firmware
/sys/class/backlight/acpi_video1/actual_brightness:7
/sys/class/backlight/acpi_video1/bl_power:0
/sys/class/backlight/acpi_video1/brightness:0
grep: /sys/class/backlight/acpi_video1/device: Is a directory
/sys/class/backlight/acpi_video1/max_brightness:7
grep: /sys/class/backlight/acpi_video1/power: Is a directory
grep: /sys/class/backlight/acpi_video1/subsystem: Is a directory
/sys/class/backlight/acpi_video1/type:firmware
/sys/class/backlight/intel_backlight/actual_brightness:309
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:4648
grep: /sys/class/backlight/intel_backlight/device: Is a directory
/sys/class/backlight/intel_backlight/max_brightness:4648
grep: /sys/class/backlight/intel_backlight/power: Is a directory
grep: /sys/class/backlight/intel_backlight/subsystem: Is a directory
/sys/class/backlight/intel_backlight/type:raw

[Toz]

Can you post back:

cat /proc/cmdline

Which of the following sets of commands actually change the brightness:

echo 3 | sudo tee /sys/class/backlight/acpi_video0/brightness
echo 7 | sudo tee /sys/class/backlight/acpi_video0/brightness

echo 5 | sudo tee /sys/class/backlight/acpi_video1/brightness
echo 0 | sudo tee /sys/class/backlight/acpi_video1/brightness

echo 2324 | sudo tee /sys/class/backlight/intel_backlight/brightness
echo 4648 | sudo tee /sys/class/backlight/intel_backlight/brightness

[ttsdinesh]

O/p for cat /proc/cmdline is

BOOT_IMAGE=/boot/vmlinuz-3.9.0-030900-generic root=UUID=a526fb85-2653-479a-8aa5-035a2281db46 ro quiet splash

Following lines change the brightness.


echo 2324 | sudo tee /sys/class/backlight/intel_backlight/brightnessecho 4648 | sudo tee /sys/class/backlight/intel_backlight/brightness

echo 3 | sudo tee /sys/class/backlight/acpi_video0/brightnessecho 7 | sudo tee /sys/class/backlight/acpi_video0/brightness

[Toz]

O/p for cat /proc/cmdline is

BOOT_IMAGE=/boot/vmlinuz-3.9.0-030900-generic root=UUID=a526fb85-2653-479a-8aa5-035a2281db46 ro quiet splash

You are missing the acpi_iso=Linux acpi_backlight=vendor kernel parameters from post #2. Can you re-add them, this time follow the "Permanently Add a Kernel Boot Parameter" instructions in the "Kernel Boot Parameters" link in my signature. After you have rebooted, check that the parameters are in effect (should be displayed in the results of "cat /proc/cmdline").

Then, check the brightness again, especially after a resume. If the problem persists, reply back with:

cat /proc/cmdline

for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; cat $i/max_brightness; done

...and try once again to see which of the interfaces allow for brightness adjustements based on my previous post.

[ttsdinesh]

This is the line in my /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" acpi_osi=Linux acpi_backlight=vendor

Is this correct or should it be

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

I'm confused in adding the parameter inside the double quote. Please provide me an example.

[Toz]

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=Linux acpi_backlight=vendor"

^^^^^This option is correct. Save the file then run:

sudo update-grub

...then reboot.

[ttsdinesh]

Now when I reboot the brightness is not set to 100% but around 80%. But it is ok for me. When I suspend and open again the brightness is preserved.

Thank you Toz !!

[ikt]

Closed at OP request.