I am also a Samsung Chronos 7 user on a fresh dual boot of Linux Mint
with Windows 10.
For me, a brightness bar appeared an moved according to me pressing Fn+F2/F3,
but the actual brightness would stay the same. If I pressed Fn+F2 until the
brightness bar was 0 the screen would turn off.
I could see that the value stored in
/sys/class/backlight/intel_backlight/brightness changes when I press Fn+F2/F3
but this wasn't changing the brightness as I said.
When I found the current bug report I replaced the line
[GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"]
with
[GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_osi=linux acpi_backlight=video"]
Then I ran [sudo update-grub] in the terminal and restarted my system.
When I had done so, a directory named /sys/class/backlight/acpi_video0 appeared.
The value in /sys/class/backlight/acpi_video0/brightness was 50. I edited it to
be 30, and my brightness suddenly changed!!
Fn+F2/F3 was still not working so I tred a tip I've read several other places
by writing the 20-intel.conf file to /usr/share/X11/xorg.conf.d/20-intel.conf
The contents of 20-intel.conf:
Section "Device"
Identifier "Intel Graphics"
Driver "i915"
Option "AccelMethod" "sna"
Option "Backlight" "acpi_video0"
BusID "PCI:0:2:0"
EndSection
I had before used
Driver "intel"
unsuccessfully but changing it to "i915" seems it may have done the trick. You
can find which driver you are using by "lspci -k" and searching throught the
list for your graphics card.
Also before I used
Option "Backlight" "intel_backlight"
but this time I used "acpi_video0" because the brightness actually responds to
value in acpi_video0/brightness and not to the one in
intel_backlight/brightness.
After shutting down my system once more, my Fn+F2/F3 screen brightness buttons
work!
A last check:
cat /sys/class/acpi_video0/brightness
cat /sys/class/intel_backlight/brightness
shows that only the former's value changes when I use Fn+F2/F3 now, as one
would guess.
Chronos 7 is getting old but maybe this can help someone else too.
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https://bugs.launchpad.net/bugs/1485246
Title:
Backlight issue - Samsung Chronos 7 (model - NP770Z5E)
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