nvidia backlight brightness problem

Problem

Unity shows control while I press the Fn+Increase/Descrese brightness, but nothing happens. In console brightness doesn't work too while X server is running.

Checked solutions

I have tried ALL POSSIBLE solutions of this problem in google and nothing works:

write acpi_backlight in grub
reinstall drivers with apt purge nvidia*
write "EnableBrightnessControl=1" in xorg.conf
install nvidia-375.66, nvidia-378.13, 381.22, 384.47
"xbacklight -set X" doesn't work
changing /sys/class/backlight/brightness
update linux kernel from 4.8 to 4.10 and 4.12
replace EDID from old matrix (it breaks everything)
setpci -v -H1 -s 00:01.0 3e.W=0 and then change backlight using Fn+keys.
xrandr --output DP-0 --brightness 0.5 --- bad solution

My system and situation

I used N173HHE-G32 display matrix in my laptop before and everything was OK. But today I've replaced it to B173HAN01.2 and this problem has started. On Windows 10 I've solved it by reinstalling drivers on nvidia-376 from official MSI website.

So, I can see the next sequence: at laptop start brightness is maximum, then it is minimum (and working) while "initramfs ..." text is showing in console. And after X server starts brightness is maximum (broken) again. When X server stops brightness is working again!

MSI GT73VR 7RF, Ubuntu 16.04.2 LTS, NVidia GeForce GTX1080, B173HAN01.2 display matrix

uname -a 
4.8.0-58-generic #63~16.04.1-Ubuntu SMP Mon Jun 26 18:08:51 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lspci | grep -i vga
01:00.0 VGA compatible controller: NVIDIA Corporation Device 1be0 (rev a1)

However!

But when I use nvidia-378 it WORKS! Unfortunately 378 has a critical bugs after suspend mode in Unity interface :(((

Please help, my eyes are in blood (it's very bright for them) and I don't know what to do...

Updated! After two years I understood that problem is inside of lightdm (or X server). When I stop it everything is ok...

Update June 16, 2019

Last month, 2 years after problem was reported, OP discovered LightDM (Ubuntu Unity Desktop Manager) was source of problem. That said, in addition to the list below, there is another grub parameter that can be tried:

video.use_native_backlight=1

See this answer for more.

Original Answer

The ultimate reference seems to be in Arch Linux which is a site I've turned to many times to fix difficult problems.

Kernel Parameters

Looking at your cat /proc/cmdline there are no extra kernel parameters passed. The above link states:

Sometimes, ACPI does not work well due to different motherboard implementations and ACPI quirks. This includes some laptops with dual graphics (e.g. Nvidia/Radeon dedicated GPU with Intel/AMD integrated GPU). On Nvidia Optimus laptops, the kernel parameter nomodeset can interfere with the ability to adjust the backlight. Additionally, ACPI sometimes needs to register its own acpi_video0 backlight even if one already exists (such as intel_backlight), which can be done by adding one of the following kernel parameters:

acpi_backlight=video
acpi_backlight=vendor
acpi_backlight=native

If you find that changing the acpi_video0 backlight does not actually change the brightness, you may need to use acpi_backlight=none.

Try each of the acpi_backlight=xxxx options on your grub kernel paremeters line

When `xbacklight` doesn't work

You've tried xbacklight already and the link above addresses this:

On some systems, the brighness hotkeys on your keyboard correctly modify the values of the acpi interface in /sys/class/backlight/acpi_video0/actual_brightness (As we tried in comments) but the brightness of the screen is not changed. Brigthness applets from desktop environments (ie Ubuntu brightness setting slider bar) may also show changes to no effect.

If you have tested the recommended kernel parameters and only xbacklight works, then you may be facing an incompatibility between your BIOS and kernel driver.

In this case the only solution is to wait for a fix either from the BIOS or GPU driver manufacturer.

A workaround is to use the inotify kernel api to trigger xbacklight each time the value of /sys/class/backlight/acpi_video0/actual_brightness changes.

First install inotify-tools. Then create a script around inotify that will be launched upon each boot or through autostart.

Below is script you need to create called: /usr/local/bin/xbacklightmon

#!/bin/sh

path=/sys/class/backlight/acpi_video0

luminance() {
    read -r level < "$path"/actual_brightness
    factor=$((100 / max))
    printf '%d\n' "$((level * factor))"
}

read -r max < "$path"/max_brightness

xbacklight -set "$(luminance)"

inotifywait -me modify --format '' "$path"/actual_brightness | while read; do
    xbacklight -set "$(luminance)"
done

There is a lot more in the link above but these steps are a good place to start.

Dedicated Forums

For additional support there are dedicated Linux Graphics forums:

Phoronix Linux/AMD/Nvidia support with many Ubuntu users
Nvidia Linux Developers Forum (with many Ubuntu specific topics)

Per wineunuuchs2unix's request, I am reposting my answer to a similar question here.

Try `acpi_osi=`

On upgrading to Bionic a few days ago, I encountered a similar problem (I have an NVIDIA GeForce GTX 1060 Mobile, but for me /sys/class/backlight is showing as empty).

In working through the backlight debugging procedure, I discovered a workaround via kernel parameters:

In "Software & Updates" → "Additional Drivers", make sure that you have nvidia-driver-396 (or whichever metapackage is current; 396 is the latest at the time of writing) selected.
Edit /etc/default/grub by running the command sudo nano /etc/default/grub (optionally replacing nano with your favorite editor).
Find the line that sets GRUB_CMDLINE_LINUX_DEFAULT and add acpi_osi= at the end inside of the quotes. On most systems this will leave you with a line reading GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=".
Save and exit the editor.
Run the command sudo update-grub and reboot.

(If these steps do not work, restore your settings by repeating the process, but removing acpi_osi= when you edit the GRUB configuration.)

Another workaround, if it is an option for you, is to switch to a mainline kernel. In particular, I do not see the problem under mainline kernel version 4.17.

(Bug reported here.)

Hi I apologise if this is something the clever people have already ruled out, as I am far from familiar with the command line, but after a reinstall i hit this problem and all the above solutions didn't work for me (MSI pe706QE nvidia 960m).

I was editing /etc/default/grub by:

gksudo 'insert editor of choice not in quotes' /etc/default/grub

and noticed the nomodeset was still sitting in the bottom of the file (I don't remember permanently adding it) and removed it.

save the file and run:

sudo update-grub

all working again with shortcut keys #noobie fail hope this can help someone.

one program to solve all this problem !!!

i have GTX 1060 6Gb desktop ubuntu 16.04

NO need to do anything, just install brightness-controller with the ppa :

https://launchpad.net/~apandada1/+archive/ubuntu/brightness-controller/

solved the issue for me (see screenshots) however it conflicts with redshift so you need to remove redshift

you can add it to startup for convenient use

I have a Sony VPCEH notebook, I had the same problem. I tried this solution that worked for me: http://ubuntuforums.org/showthread.php?t=2221452#6

Briefly: With root privileges, create the file /usr/share/X11/xorg.conf.d/20-nvidia.conf with the following content

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 410M"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection

Log out and back in again to test. The link above also states: "If something goes wrong, simply delete that file and reboot to recover the system", but I didn't need that addition.

After logout and login the brightness control started to work again. I hope it helps you too...

or this one after works with ubuntu 16.04 under my laptop sony VPCEJ2C5E but with nvidia 378.13 i don't have use for the moment the 390.25 drivers.

I was able to get my brightness keys working on my Lenovo W530 on Ubuntu 12.04. These days X automatically configures itself, so creating an xorg.conf file might make your system inflexible. Instead you can add a section to a file in /usr/share/X11/xorg.conf.d/ and X will include that section in the configuration that it automatically generates. So to get the screen brightness keys working with your Nvidia graphics card, create a file in the xorg.conf.d directory, e.g: sudo gedit /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf Paste the following into the file:

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "Quadro K1000M"
    Option         "RegistryDwords" "EnableBrightnessControl=1"
EndSection

Log out and log back in, or reboot, and your brightness keys should now work!

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