I can't lower the backlight/brightness





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4















Why I can't control the brightness/backlight level?



At the first:



Notebook Positivo BGH - C500 Series. 
Processor: AMD C60 series (dual core 800 mhz-1ghz)
GPU: Radeon HD 6290 (worked with fglrx/Catalyst)


Hello everybody, this is my first post in 8-years-use of Ubuntu/Kubuntu, I've never had problems with any version, but when I've upgraded from Willy to Xenial I haven't take care in the latest version that the AMD/ATI property drivers (fglrx) have been discontinued or unsupported by the developers, and they advice against not upgrade for AMD users. The Fn keys dosen't work!



However, after upgrade, when I was configuring, I want install drivers from console:



sudo apt-get install fglrx fglrx-updates 
"fglrx" and "fglrx-updates" has no candidates


In the version Willy (and previous versions), I can't control or lower the brightness/backlight util the property drivers have been instaled.



In Ubuntu 16.04, the drivers are:



xserver-xorg-video-amdgpu
xserver-xorg-video-radeon


And These are open drivers, but this is not the trouble really.



I've tried the following procedures:



I tried to put various links, but the newbies can't post more 2 links



Abstract:



1. Can't change backlight level by installing driver.



    sudo apt-get install xserver-org-video-amdgpu
sudo apt-get install xserver-org-video-radeon


##2. It persist high shine, despite modifing /sys/class/backlight, and the promp shows me (radeon_bl0 is present):



    lspci | grep ati
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wrestler [Radeon HD 6290]
ls /sys/class/backlight
radeon_bl0


Inside the folder, brightness, max_brightness, actual_brightness, bl_power and others are present



    echo > 10 /sys/class/backlight/radeon_bl0/brightness 


There is no effect



    echo > 100 /sys/class/backlight/radeon_bl0/max_brightness
permission denied
chmod 0777 /sys/class/backlight/radeon_bl0/max_brightness
nano /sys/class/backlight/radeon_bl0/max_brighness
modifing 255 to 100
Ctrl+O > I/O Error
chmod 0777 /sys/class/backlight
The same result > I/O Error


And find another way:



    ls -alh /sys/class/backlight
lrwxrwxrwx 1 root root 0 abr 23 12:23 radeon_bl0 -> ../../devices/pci0000:00/0000:00:01.0/drm/card0/card0-LVDS-1/radeon_bl0


And trying the same, and no effect.



3. Modifing the grub:



    GRUB_CMDLINE_LINUX="acpi_osi=Linux" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=none" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=vendor" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=video" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight0" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=radeon_bl0" | No effect


Rebooting and edit grub (with the same sentences) before start Ubuntu, strangely It don't start.
Starting in "recovery mode", /sys/class/backlight, shows me:



     acpi_video0


But the SDDM dosen't start.



4. Adding the X11 configuration.



      cd /usr/share/X11/xorg.conf.d
dir > 10-amdgpu.conf is present
nano 10-amdgpu.conf | shows me

Section "OutputClass"
Identifier "AMDgpu"
MatchDriver "amdgpu"
Driver "amdgpu"
EndSection
I added

Section "Device"
Identifier "card0" | put also "AMDgpu"
Driver "amdgpu"
Option "Backlight" "radeon_bl0"
BusID "PCI:00:01:01"
End Section


But it dosen't work, due option "Backlight" is for intel driver. I revised man of amdgpu and not figure this option. In several times, neither starts SDDM.



5. Using the command setpci:



     setpci -s 00:01.0 F4.B=7F | Not work
setpci -s 00:01.0 F4.B=FF | Not work
setpci -s 00:01.0 F4.B=50 | Not work
setpci -s 00:01.0 F4.B=80 | Not work


This video card not support by the setpci



6. Installing xbacklight



     sudo apt-get install xbacklight
xbacklight -s 80 | there is no effect
No outputs have backlight property
xbacklight -d LVDS -s 80
RANDR Query Version returned error -1


It dosen't work, I've searched, and xbacklight is deprecated for xf86-video-ati for control of backlight, I've installed script "light" (lightscript) but It dosen't work too.



7. Making udev rule:



          nano /etc/udev/rules.d/81-backlight.rules

# Set backlight level to 8
SUBSYSTEM=="backlight", ACTION=="add", KERNEL=="acpi_video0", ATTR{brightness}="8"
Save & Exit and there is no effect after boot


8. Using systemd-backlight service.



           I don't understeand how this works, but I've got this from the prompt: 
systemctl list-units | grep -i backl

systemd-backlight@backlight:radeon_bl0.service loaded active exited Load/Save Screen Backlight Brightness of backlight:radeon_bl0

system-systemdx2dbacklight.slice loaded active active system-systemdx2dbacklight.slice


The systemd-backlight service is loaded for /sys/class/backlight ! But It dosen't work, the backlight don't change.



9. Using xrandr



       Finally I put in the console:
xrandr --output LVDS-1 --brightness 0.6 | 0.4 | 0.3
Previously identified output


This "worked" for me, but when I restart the values of xrandr going to default, by more than I put xrandr --output LVDS1 --brightness 0.5 at start session. (On Kde by the System Settings>Start and Shutdown)



Conclussion



In all cases, the brightness/backlight ever is high, it dosen't matter I do, the Fn Keys don't work, and the Kde Indicator for brightness goes to 0 and the LCD looks the Christmas tree because it's turn up/down infinitely.



Anyone have more ideas?



Sorry for my bad english!










share|improve this question























  • I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

    – Matias González
    Apr 28 '16 at 12:35











  • Did you fix your problem?

    – Max Tkachenko
    Jul 20 '17 at 16:12


















4















Why I can't control the brightness/backlight level?



At the first:



Notebook Positivo BGH - C500 Series. 
Processor: AMD C60 series (dual core 800 mhz-1ghz)
GPU: Radeon HD 6290 (worked with fglrx/Catalyst)


Hello everybody, this is my first post in 8-years-use of Ubuntu/Kubuntu, I've never had problems with any version, but when I've upgraded from Willy to Xenial I haven't take care in the latest version that the AMD/ATI property drivers (fglrx) have been discontinued or unsupported by the developers, and they advice against not upgrade for AMD users. The Fn keys dosen't work!



However, after upgrade, when I was configuring, I want install drivers from console:



sudo apt-get install fglrx fglrx-updates 
"fglrx" and "fglrx-updates" has no candidates


In the version Willy (and previous versions), I can't control or lower the brightness/backlight util the property drivers have been instaled.



In Ubuntu 16.04, the drivers are:



xserver-xorg-video-amdgpu
xserver-xorg-video-radeon


And These are open drivers, but this is not the trouble really.



I've tried the following procedures:



I tried to put various links, but the newbies can't post more 2 links



Abstract:



1. Can't change backlight level by installing driver.



    sudo apt-get install xserver-org-video-amdgpu
sudo apt-get install xserver-org-video-radeon


##2. It persist high shine, despite modifing /sys/class/backlight, and the promp shows me (radeon_bl0 is present):



    lspci | grep ati
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wrestler [Radeon HD 6290]
ls /sys/class/backlight
radeon_bl0


Inside the folder, brightness, max_brightness, actual_brightness, bl_power and others are present



    echo > 10 /sys/class/backlight/radeon_bl0/brightness 


There is no effect



    echo > 100 /sys/class/backlight/radeon_bl0/max_brightness
permission denied
chmod 0777 /sys/class/backlight/radeon_bl0/max_brightness
nano /sys/class/backlight/radeon_bl0/max_brighness
modifing 255 to 100
Ctrl+O > I/O Error
chmod 0777 /sys/class/backlight
The same result > I/O Error


And find another way:



    ls -alh /sys/class/backlight
lrwxrwxrwx 1 root root 0 abr 23 12:23 radeon_bl0 -> ../../devices/pci0000:00/0000:00:01.0/drm/card0/card0-LVDS-1/radeon_bl0


And trying the same, and no effect.



3. Modifing the grub:



    GRUB_CMDLINE_LINUX="acpi_osi=Linux" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=none" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=vendor" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=video" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight0" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=radeon_bl0" | No effect


Rebooting and edit grub (with the same sentences) before start Ubuntu, strangely It don't start.
Starting in "recovery mode", /sys/class/backlight, shows me:



     acpi_video0


But the SDDM dosen't start.



4. Adding the X11 configuration.



      cd /usr/share/X11/xorg.conf.d
dir > 10-amdgpu.conf is present
nano 10-amdgpu.conf | shows me

Section "OutputClass"
Identifier "AMDgpu"
MatchDriver "amdgpu"
Driver "amdgpu"
EndSection
I added

Section "Device"
Identifier "card0" | put also "AMDgpu"
Driver "amdgpu"
Option "Backlight" "radeon_bl0"
BusID "PCI:00:01:01"
End Section


But it dosen't work, due option "Backlight" is for intel driver. I revised man of amdgpu and not figure this option. In several times, neither starts SDDM.



5. Using the command setpci:



     setpci -s 00:01.0 F4.B=7F | Not work
setpci -s 00:01.0 F4.B=FF | Not work
setpci -s 00:01.0 F4.B=50 | Not work
setpci -s 00:01.0 F4.B=80 | Not work


This video card not support by the setpci



6. Installing xbacklight



     sudo apt-get install xbacklight
xbacklight -s 80 | there is no effect
No outputs have backlight property
xbacklight -d LVDS -s 80
RANDR Query Version returned error -1


It dosen't work, I've searched, and xbacklight is deprecated for xf86-video-ati for control of backlight, I've installed script "light" (lightscript) but It dosen't work too.



7. Making udev rule:



          nano /etc/udev/rules.d/81-backlight.rules

# Set backlight level to 8
SUBSYSTEM=="backlight", ACTION=="add", KERNEL=="acpi_video0", ATTR{brightness}="8"
Save & Exit and there is no effect after boot


8. Using systemd-backlight service.



           I don't understeand how this works, but I've got this from the prompt: 
systemctl list-units | grep -i backl

systemd-backlight@backlight:radeon_bl0.service loaded active exited Load/Save Screen Backlight Brightness of backlight:radeon_bl0

system-systemdx2dbacklight.slice loaded active active system-systemdx2dbacklight.slice


The systemd-backlight service is loaded for /sys/class/backlight ! But It dosen't work, the backlight don't change.



9. Using xrandr



       Finally I put in the console:
xrandr --output LVDS-1 --brightness 0.6 | 0.4 | 0.3
Previously identified output


This "worked" for me, but when I restart the values of xrandr going to default, by more than I put xrandr --output LVDS1 --brightness 0.5 at start session. (On Kde by the System Settings>Start and Shutdown)



Conclussion



In all cases, the brightness/backlight ever is high, it dosen't matter I do, the Fn Keys don't work, and the Kde Indicator for brightness goes to 0 and the LCD looks the Christmas tree because it's turn up/down infinitely.



Anyone have more ideas?



Sorry for my bad english!










share|improve this question























  • I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

    – Matias González
    Apr 28 '16 at 12:35











  • Did you fix your problem?

    – Max Tkachenko
    Jul 20 '17 at 16:12














4












4








4


2






Why I can't control the brightness/backlight level?



At the first:



Notebook Positivo BGH - C500 Series. 
Processor: AMD C60 series (dual core 800 mhz-1ghz)
GPU: Radeon HD 6290 (worked with fglrx/Catalyst)


Hello everybody, this is my first post in 8-years-use of Ubuntu/Kubuntu, I've never had problems with any version, but when I've upgraded from Willy to Xenial I haven't take care in the latest version that the AMD/ATI property drivers (fglrx) have been discontinued or unsupported by the developers, and they advice against not upgrade for AMD users. The Fn keys dosen't work!



However, after upgrade, when I was configuring, I want install drivers from console:



sudo apt-get install fglrx fglrx-updates 
"fglrx" and "fglrx-updates" has no candidates


In the version Willy (and previous versions), I can't control or lower the brightness/backlight util the property drivers have been instaled.



In Ubuntu 16.04, the drivers are:



xserver-xorg-video-amdgpu
xserver-xorg-video-radeon


And These are open drivers, but this is not the trouble really.



I've tried the following procedures:



I tried to put various links, but the newbies can't post more 2 links



Abstract:



1. Can't change backlight level by installing driver.



    sudo apt-get install xserver-org-video-amdgpu
sudo apt-get install xserver-org-video-radeon


##2. It persist high shine, despite modifing /sys/class/backlight, and the promp shows me (radeon_bl0 is present):



    lspci | grep ati
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wrestler [Radeon HD 6290]
ls /sys/class/backlight
radeon_bl0


Inside the folder, brightness, max_brightness, actual_brightness, bl_power and others are present



    echo > 10 /sys/class/backlight/radeon_bl0/brightness 


There is no effect



    echo > 100 /sys/class/backlight/radeon_bl0/max_brightness
permission denied
chmod 0777 /sys/class/backlight/radeon_bl0/max_brightness
nano /sys/class/backlight/radeon_bl0/max_brighness
modifing 255 to 100
Ctrl+O > I/O Error
chmod 0777 /sys/class/backlight
The same result > I/O Error


And find another way:



    ls -alh /sys/class/backlight
lrwxrwxrwx 1 root root 0 abr 23 12:23 radeon_bl0 -> ../../devices/pci0000:00/0000:00:01.0/drm/card0/card0-LVDS-1/radeon_bl0


And trying the same, and no effect.



3. Modifing the grub:



    GRUB_CMDLINE_LINUX="acpi_osi=Linux" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=none" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=vendor" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=video" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight0" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=radeon_bl0" | No effect


Rebooting and edit grub (with the same sentences) before start Ubuntu, strangely It don't start.
Starting in "recovery mode", /sys/class/backlight, shows me:



     acpi_video0


But the SDDM dosen't start.



4. Adding the X11 configuration.



      cd /usr/share/X11/xorg.conf.d
dir > 10-amdgpu.conf is present
nano 10-amdgpu.conf | shows me

Section "OutputClass"
Identifier "AMDgpu"
MatchDriver "amdgpu"
Driver "amdgpu"
EndSection
I added

Section "Device"
Identifier "card0" | put also "AMDgpu"
Driver "amdgpu"
Option "Backlight" "radeon_bl0"
BusID "PCI:00:01:01"
End Section


But it dosen't work, due option "Backlight" is for intel driver. I revised man of amdgpu and not figure this option. In several times, neither starts SDDM.



5. Using the command setpci:



     setpci -s 00:01.0 F4.B=7F | Not work
setpci -s 00:01.0 F4.B=FF | Not work
setpci -s 00:01.0 F4.B=50 | Not work
setpci -s 00:01.0 F4.B=80 | Not work


This video card not support by the setpci



6. Installing xbacklight



     sudo apt-get install xbacklight
xbacklight -s 80 | there is no effect
No outputs have backlight property
xbacklight -d LVDS -s 80
RANDR Query Version returned error -1


It dosen't work, I've searched, and xbacklight is deprecated for xf86-video-ati for control of backlight, I've installed script "light" (lightscript) but It dosen't work too.



7. Making udev rule:



          nano /etc/udev/rules.d/81-backlight.rules

# Set backlight level to 8
SUBSYSTEM=="backlight", ACTION=="add", KERNEL=="acpi_video0", ATTR{brightness}="8"
Save & Exit and there is no effect after boot


8. Using systemd-backlight service.



           I don't understeand how this works, but I've got this from the prompt: 
systemctl list-units | grep -i backl

systemd-backlight@backlight:radeon_bl0.service loaded active exited Load/Save Screen Backlight Brightness of backlight:radeon_bl0

system-systemdx2dbacklight.slice loaded active active system-systemdx2dbacklight.slice


The systemd-backlight service is loaded for /sys/class/backlight ! But It dosen't work, the backlight don't change.



9. Using xrandr



       Finally I put in the console:
xrandr --output LVDS-1 --brightness 0.6 | 0.4 | 0.3
Previously identified output


This "worked" for me, but when I restart the values of xrandr going to default, by more than I put xrandr --output LVDS1 --brightness 0.5 at start session. (On Kde by the System Settings>Start and Shutdown)



Conclussion



In all cases, the brightness/backlight ever is high, it dosen't matter I do, the Fn Keys don't work, and the Kde Indicator for brightness goes to 0 and the LCD looks the Christmas tree because it's turn up/down infinitely.



Anyone have more ideas?



Sorry for my bad english!










share|improve this question














Why I can't control the brightness/backlight level?



At the first:



Notebook Positivo BGH - C500 Series. 
Processor: AMD C60 series (dual core 800 mhz-1ghz)
GPU: Radeon HD 6290 (worked with fglrx/Catalyst)


Hello everybody, this is my first post in 8-years-use of Ubuntu/Kubuntu, I've never had problems with any version, but when I've upgraded from Willy to Xenial I haven't take care in the latest version that the AMD/ATI property drivers (fglrx) have been discontinued or unsupported by the developers, and they advice against not upgrade for AMD users. The Fn keys dosen't work!



However, after upgrade, when I was configuring, I want install drivers from console:



sudo apt-get install fglrx fglrx-updates 
"fglrx" and "fglrx-updates" has no candidates


In the version Willy (and previous versions), I can't control or lower the brightness/backlight util the property drivers have been instaled.



In Ubuntu 16.04, the drivers are:



xserver-xorg-video-amdgpu
xserver-xorg-video-radeon


And These are open drivers, but this is not the trouble really.



I've tried the following procedures:



I tried to put various links, but the newbies can't post more 2 links



Abstract:



1. Can't change backlight level by installing driver.



    sudo apt-get install xserver-org-video-amdgpu
sudo apt-get install xserver-org-video-radeon


##2. It persist high shine, despite modifing /sys/class/backlight, and the promp shows me (radeon_bl0 is present):



    lspci | grep ati
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wrestler [Radeon HD 6290]
ls /sys/class/backlight
radeon_bl0


Inside the folder, brightness, max_brightness, actual_brightness, bl_power and others are present



    echo > 10 /sys/class/backlight/radeon_bl0/brightness 


There is no effect



    echo > 100 /sys/class/backlight/radeon_bl0/max_brightness
permission denied
chmod 0777 /sys/class/backlight/radeon_bl0/max_brightness
nano /sys/class/backlight/radeon_bl0/max_brighness
modifing 255 to 100
Ctrl+O > I/O Error
chmod 0777 /sys/class/backlight
The same result > I/O Error


And find another way:



    ls -alh /sys/class/backlight
lrwxrwxrwx 1 root root 0 abr 23 12:23 radeon_bl0 -> ../../devices/pci0000:00/0000:00:01.0/drm/card0/card0-LVDS-1/radeon_bl0


And trying the same, and no effect.



3. Modifing the grub:



    GRUB_CMDLINE_LINUX="acpi_osi=Linux" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=none" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=vendor" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=video" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight0" | No effect
GRUB_CMDLINE_LINUX="acpi_backlight=radeon_bl0" | No effect


Rebooting and edit grub (with the same sentences) before start Ubuntu, strangely It don't start.
Starting in "recovery mode", /sys/class/backlight, shows me:



     acpi_video0


But the SDDM dosen't start.



4. Adding the X11 configuration.



      cd /usr/share/X11/xorg.conf.d
dir > 10-amdgpu.conf is present
nano 10-amdgpu.conf | shows me

Section "OutputClass"
Identifier "AMDgpu"
MatchDriver "amdgpu"
Driver "amdgpu"
EndSection
I added

Section "Device"
Identifier "card0" | put also "AMDgpu"
Driver "amdgpu"
Option "Backlight" "radeon_bl0"
BusID "PCI:00:01:01"
End Section


But it dosen't work, due option "Backlight" is for intel driver. I revised man of amdgpu and not figure this option. In several times, neither starts SDDM.



5. Using the command setpci:



     setpci -s 00:01.0 F4.B=7F | Not work
setpci -s 00:01.0 F4.B=FF | Not work
setpci -s 00:01.0 F4.B=50 | Not work
setpci -s 00:01.0 F4.B=80 | Not work


This video card not support by the setpci



6. Installing xbacklight



     sudo apt-get install xbacklight
xbacklight -s 80 | there is no effect
No outputs have backlight property
xbacklight -d LVDS -s 80
RANDR Query Version returned error -1


It dosen't work, I've searched, and xbacklight is deprecated for xf86-video-ati for control of backlight, I've installed script "light" (lightscript) but It dosen't work too.



7. Making udev rule:



          nano /etc/udev/rules.d/81-backlight.rules

# Set backlight level to 8
SUBSYSTEM=="backlight", ACTION=="add", KERNEL=="acpi_video0", ATTR{brightness}="8"
Save & Exit and there is no effect after boot


8. Using systemd-backlight service.



           I don't understeand how this works, but I've got this from the prompt: 
systemctl list-units | grep -i backl

systemd-backlight@backlight:radeon_bl0.service loaded active exited Load/Save Screen Backlight Brightness of backlight:radeon_bl0

system-systemdx2dbacklight.slice loaded active active system-systemdx2dbacklight.slice


The systemd-backlight service is loaded for /sys/class/backlight ! But It dosen't work, the backlight don't change.



9. Using xrandr



       Finally I put in the console:
xrandr --output LVDS-1 --brightness 0.6 | 0.4 | 0.3
Previously identified output


This "worked" for me, but when I restart the values of xrandr going to default, by more than I put xrandr --output LVDS1 --brightness 0.5 at start session. (On Kde by the System Settings>Start and Shutdown)



Conclussion



In all cases, the brightness/backlight ever is high, it dosen't matter I do, the Fn Keys don't work, and the Kde Indicator for brightness goes to 0 and the LCD looks the Christmas tree because it's turn up/down infinitely.



Anyone have more ideas?



Sorry for my bad english!







brightness 16.04 backlight amd-graphics






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Apr 23 '16 at 20:13









Matias GonzálezMatias González

2112




2112













  • I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

    – Matias González
    Apr 28 '16 at 12:35











  • Did you fix your problem?

    – Max Tkachenko
    Jul 20 '17 at 16:12



















  • I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

    – Matias González
    Apr 28 '16 at 12:35











  • Did you fix your problem?

    – Max Tkachenko
    Jul 20 '17 at 16:12

















I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

– Matias González
Apr 28 '16 at 12:35





I tried in this week start in recovery mode with the backlight controlled by BIOS, but when plymouth appear, the brightness sets to high.

– Matias González
Apr 28 '16 at 12:35













Did you fix your problem?

– Max Tkachenko
Jul 20 '17 at 16:12





Did you fix your problem?

– Max Tkachenko
Jul 20 '17 at 16:12










2 Answers
2






active

oldest

votes


















0














There's something very odd about the syntax you're using to write to the files in /sys/class/backlight/. Please try this, instead:



echo 128 | sudo tee /sys/class/backlight/radeon_bl0/brightness


By the way, you were not able to modify "max_brightness" because that file is just there to let you know the maximum brightness you can use. You need to change the file named "brightness".



About your shell syntax: The shell redirection operator > only works if you're already running a shell as root (for example, using sudo -s), but I should let you know that doing so is generally considered a bad idea. Logging in to a root shell gives you great power; and with great power comes great whopping mistakes. It's easy to forget you're running as root and then accidentally mess up your whole system. That's why I recommend sudo, as in the example above. Sudo is a reminder to be careful: anything after the word sudo is normally off-limits and potentially dangerous.



However, if you are curious, it is possible to use the > file
redirection operator the way you were asking, but you'd need to change
the arguments around. The part that comes after the > is the
filename to write to, the part before it is the command whose output
you want to redirect. So, for example,



$ sudo -s
# cd /sys/class/backlight/*/
# echo 128
128
# echo 100 > brightness
# cat brightness
100
# echo 200 > brightness
# cat max_brightness
255
# cat max_brightness > brightness
# cat brightness
255
# exit
$


(You'll notice your prompt changes to a hash mark when you're running a
root shell. That's a subtle warning sign. Typing exit will get you
back to the safety of your normal user account.)






share|improve this answer































    0














    there is no standard brightness level resolution in universal implementation. For example one of my linux boxes is a Toshiba Satellite L510 and has an 8 bit resolution. i.e. my /sys/class/backlight/acpi_video0/brightnesswill only accept values in [0,7]. I also have seen one other system has a resolution of 23 bits. i.e. [0-22].



    To know the range of brightness values, read your /sys/class/backlight/radeon_bl0/max_brightness file. Also the value of the max_brightness file is most likely set by your system's firmware and you can not write to it. But the /sys/class/backlight/radeon_bl0/brightness file can be written to as long as the value being written is between 0 and the result of



    cat /sys/class/backlight/radeon_bl0/max_brightness



    also suspending your system and waking it up usually fixes some problems with regard to ACPI and UEFI - by extension functions keys. to suspend your system use the following command.



    sudo pm-suspend



    then wake your system by pressing the power button and check is the function keys are working.






    share|improve this answer


























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      0














      There's something very odd about the syntax you're using to write to the files in /sys/class/backlight/. Please try this, instead:



      echo 128 | sudo tee /sys/class/backlight/radeon_bl0/brightness


      By the way, you were not able to modify "max_brightness" because that file is just there to let you know the maximum brightness you can use. You need to change the file named "brightness".



      About your shell syntax: The shell redirection operator > only works if you're already running a shell as root (for example, using sudo -s), but I should let you know that doing so is generally considered a bad idea. Logging in to a root shell gives you great power; and with great power comes great whopping mistakes. It's easy to forget you're running as root and then accidentally mess up your whole system. That's why I recommend sudo, as in the example above. Sudo is a reminder to be careful: anything after the word sudo is normally off-limits and potentially dangerous.



      However, if you are curious, it is possible to use the > file
      redirection operator the way you were asking, but you'd need to change
      the arguments around. The part that comes after the > is the
      filename to write to, the part before it is the command whose output
      you want to redirect. So, for example,



      $ sudo -s
      # cd /sys/class/backlight/*/
      # echo 128
      128
      # echo 100 > brightness
      # cat brightness
      100
      # echo 200 > brightness
      # cat max_brightness
      255
      # cat max_brightness > brightness
      # cat brightness
      255
      # exit
      $


      (You'll notice your prompt changes to a hash mark when you're running a
      root shell. That's a subtle warning sign. Typing exit will get you
      back to the safety of your normal user account.)






      share|improve this answer




























        0














        There's something very odd about the syntax you're using to write to the files in /sys/class/backlight/. Please try this, instead:



        echo 128 | sudo tee /sys/class/backlight/radeon_bl0/brightness


        By the way, you were not able to modify "max_brightness" because that file is just there to let you know the maximum brightness you can use. You need to change the file named "brightness".



        About your shell syntax: The shell redirection operator > only works if you're already running a shell as root (for example, using sudo -s), but I should let you know that doing so is generally considered a bad idea. Logging in to a root shell gives you great power; and with great power comes great whopping mistakes. It's easy to forget you're running as root and then accidentally mess up your whole system. That's why I recommend sudo, as in the example above. Sudo is a reminder to be careful: anything after the word sudo is normally off-limits and potentially dangerous.



        However, if you are curious, it is possible to use the > file
        redirection operator the way you were asking, but you'd need to change
        the arguments around. The part that comes after the > is the
        filename to write to, the part before it is the command whose output
        you want to redirect. So, for example,



        $ sudo -s
        # cd /sys/class/backlight/*/
        # echo 128
        128
        # echo 100 > brightness
        # cat brightness
        100
        # echo 200 > brightness
        # cat max_brightness
        255
        # cat max_brightness > brightness
        # cat brightness
        255
        # exit
        $


        (You'll notice your prompt changes to a hash mark when you're running a
        root shell. That's a subtle warning sign. Typing exit will get you
        back to the safety of your normal user account.)






        share|improve this answer


























          0












          0








          0







          There's something very odd about the syntax you're using to write to the files in /sys/class/backlight/. Please try this, instead:



          echo 128 | sudo tee /sys/class/backlight/radeon_bl0/brightness


          By the way, you were not able to modify "max_brightness" because that file is just there to let you know the maximum brightness you can use. You need to change the file named "brightness".



          About your shell syntax: The shell redirection operator > only works if you're already running a shell as root (for example, using sudo -s), but I should let you know that doing so is generally considered a bad idea. Logging in to a root shell gives you great power; and with great power comes great whopping mistakes. It's easy to forget you're running as root and then accidentally mess up your whole system. That's why I recommend sudo, as in the example above. Sudo is a reminder to be careful: anything after the word sudo is normally off-limits and potentially dangerous.



          However, if you are curious, it is possible to use the > file
          redirection operator the way you were asking, but you'd need to change
          the arguments around. The part that comes after the > is the
          filename to write to, the part before it is the command whose output
          you want to redirect. So, for example,



          $ sudo -s
          # cd /sys/class/backlight/*/
          # echo 128
          128
          # echo 100 > brightness
          # cat brightness
          100
          # echo 200 > brightness
          # cat max_brightness
          255
          # cat max_brightness > brightness
          # cat brightness
          255
          # exit
          $


          (You'll notice your prompt changes to a hash mark when you're running a
          root shell. That's a subtle warning sign. Typing exit will get you
          back to the safety of your normal user account.)






          share|improve this answer













          There's something very odd about the syntax you're using to write to the files in /sys/class/backlight/. Please try this, instead:



          echo 128 | sudo tee /sys/class/backlight/radeon_bl0/brightness


          By the way, you were not able to modify "max_brightness" because that file is just there to let you know the maximum brightness you can use. You need to change the file named "brightness".



          About your shell syntax: The shell redirection operator > only works if you're already running a shell as root (for example, using sudo -s), but I should let you know that doing so is generally considered a bad idea. Logging in to a root shell gives you great power; and with great power comes great whopping mistakes. It's easy to forget you're running as root and then accidentally mess up your whole system. That's why I recommend sudo, as in the example above. Sudo is a reminder to be careful: anything after the word sudo is normally off-limits and potentially dangerous.



          However, if you are curious, it is possible to use the > file
          redirection operator the way you were asking, but you'd need to change
          the arguments around. The part that comes after the > is the
          filename to write to, the part before it is the command whose output
          you want to redirect. So, for example,



          $ sudo -s
          # cd /sys/class/backlight/*/
          # echo 128
          128
          # echo 100 > brightness
          # cat brightness
          100
          # echo 200 > brightness
          # cat max_brightness
          255
          # cat max_brightness > brightness
          # cat brightness
          255
          # exit
          $


          (You'll notice your prompt changes to a hash mark when you're running a
          root shell. That's a subtle warning sign. Typing exit will get you
          back to the safety of your normal user account.)







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Jul 3 '17 at 11:29









          hackerb9hackerb9

          60467




          60467

























              0














              there is no standard brightness level resolution in universal implementation. For example one of my linux boxes is a Toshiba Satellite L510 and has an 8 bit resolution. i.e. my /sys/class/backlight/acpi_video0/brightnesswill only accept values in [0,7]. I also have seen one other system has a resolution of 23 bits. i.e. [0-22].



              To know the range of brightness values, read your /sys/class/backlight/radeon_bl0/max_brightness file. Also the value of the max_brightness file is most likely set by your system's firmware and you can not write to it. But the /sys/class/backlight/radeon_bl0/brightness file can be written to as long as the value being written is between 0 and the result of



              cat /sys/class/backlight/radeon_bl0/max_brightness



              also suspending your system and waking it up usually fixes some problems with regard to ACPI and UEFI - by extension functions keys. to suspend your system use the following command.



              sudo pm-suspend



              then wake your system by pressing the power button and check is the function keys are working.






              share|improve this answer






























                0














                there is no standard brightness level resolution in universal implementation. For example one of my linux boxes is a Toshiba Satellite L510 and has an 8 bit resolution. i.e. my /sys/class/backlight/acpi_video0/brightnesswill only accept values in [0,7]. I also have seen one other system has a resolution of 23 bits. i.e. [0-22].



                To know the range of brightness values, read your /sys/class/backlight/radeon_bl0/max_brightness file. Also the value of the max_brightness file is most likely set by your system's firmware and you can not write to it. But the /sys/class/backlight/radeon_bl0/brightness file can be written to as long as the value being written is between 0 and the result of



                cat /sys/class/backlight/radeon_bl0/max_brightness



                also suspending your system and waking it up usually fixes some problems with regard to ACPI and UEFI - by extension functions keys. to suspend your system use the following command.



                sudo pm-suspend



                then wake your system by pressing the power button and check is the function keys are working.






                share|improve this answer




























                  0












                  0








                  0







                  there is no standard brightness level resolution in universal implementation. For example one of my linux boxes is a Toshiba Satellite L510 and has an 8 bit resolution. i.e. my /sys/class/backlight/acpi_video0/brightnesswill only accept values in [0,7]. I also have seen one other system has a resolution of 23 bits. i.e. [0-22].



                  To know the range of brightness values, read your /sys/class/backlight/radeon_bl0/max_brightness file. Also the value of the max_brightness file is most likely set by your system's firmware and you can not write to it. But the /sys/class/backlight/radeon_bl0/brightness file can be written to as long as the value being written is between 0 and the result of



                  cat /sys/class/backlight/radeon_bl0/max_brightness



                  also suspending your system and waking it up usually fixes some problems with regard to ACPI and UEFI - by extension functions keys. to suspend your system use the following command.



                  sudo pm-suspend



                  then wake your system by pressing the power button and check is the function keys are working.






                  share|improve this answer















                  there is no standard brightness level resolution in universal implementation. For example one of my linux boxes is a Toshiba Satellite L510 and has an 8 bit resolution. i.e. my /sys/class/backlight/acpi_video0/brightnesswill only accept values in [0,7]. I also have seen one other system has a resolution of 23 bits. i.e. [0-22].



                  To know the range of brightness values, read your /sys/class/backlight/radeon_bl0/max_brightness file. Also the value of the max_brightness file is most likely set by your system's firmware and you can not write to it. But the /sys/class/backlight/radeon_bl0/brightness file can be written to as long as the value being written is between 0 and the result of



                  cat /sys/class/backlight/radeon_bl0/max_brightness



                  also suspending your system and waking it up usually fixes some problems with regard to ACPI and UEFI - by extension functions keys. to suspend your system use the following command.



                  sudo pm-suspend



                  then wake your system by pressing the power button and check is the function keys are working.







                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited Jul 3 '17 at 11:53

























                  answered Jul 3 '17 at 11:45









                  endriasendrias

                  354114




                  354114






























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