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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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1485246
Title:
Backlight issue - Samsung Chronos 7 (model - NP770Z5E)
Status in linux package in Ubuntu:
Confirmed
Bug description:
Control of screen backlight is broken with a default clean install of
Ubuntu 15.04 on my Samsung Series 7 Laptop (NP770Z5E). Setting kernel
parameter 'acpi_backlight=vendor' fixes the issue after two reboots.
Debugging information attached as per -
https://wiki.ubuntu.com/Kernel/Debugging/Backlight
ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-25-generic 3.19.0-25.26
ProcVersionSignature: Ubuntu 3.19.0-25.26-generic 3.19.8-ckt2
Uname: Linux 3.19.0-25-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.2
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: mark 1699 F.... pulseaudio
Date: Sat Aug 15 21:36:20 2015
HibernationDevice: RESUME=UUID=c4899b44-3e19-4e62-921d-cf0a1cef97ec
InstallationDate: Installed on 2015-08-12 (3 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: SAMSUNG ELECTRONICS CO., LTD. 770Z5E/780Z5E
ProcFB:
0 inteldrmfb
1 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-25-generic
root=UUID=5a02817b-1f9b-4abc-93a3-b10d5d9278ed ro quiet splash
acpi_backlight=vendor vt.handoff=7
PulseList:
Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not
accessible: Permission denied
No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-3.19.0-25-generic N/A
linux-backports-modules-3.19.0-25-generic N/A
linux-firmware 1.143.3
SourcePackage: linux
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/05/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P05ABU.142.130905.SK
dmi.board.asset.tag: No Asset Tag
dmi.board.name: NP770Z5E-S02UK
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.board.version: SEC_SW_REVISION_1234567890ABCD
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.version: N/A
dmi.modalias:
dmi:bvnAmericanMegatrendsInc.:bvrP05ABU.142.130905.SK:bd09/05/2013:svnSAMSUNGELECTRONICSCO.,LTD.:pn770Z5E/780Z5E:pvrP05ABU:rvnSAMSUNGELECTRONICSCO.,LTD.:rnNP770Z5E-S02UK:rvrSEC_SW_REVISION_1234567890ABCD:cvnSAMSUNGELECTRONICSCO.,LTD.:ct9:cvrN/A:
dmi.product.name: 770Z5E/780Z5E
dmi.product.version: P05ABU
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.
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