Can't change brightness on Acer 4810t (8.04)
Hi
8.04 all working nice and stable on my new Acer 4810t dual core, but still with some outstanding issues.
I haven't found a way to get the brightness to change at all, am wondering if anyone can help.
Looking around the brightness control could be here:
/proc/acpi/video/VGA/LCD/brightness
and if I try
cat /proc/acpi/video/VGA/LCD/brightness
I get something like
levels: 100 80 30 40 50 60 70 80 90 100
current: 70
which I've just noticed is controlled by the hotkeys. Unfortunately it has no effect on the brightness. Using the echo command has no effect on it.
There is also
/sys/class/backlight/acer_acpi/brightness
and if I try
cat /sys/class/backlight/acer_acpi/brightness
I get
9
but echo changes nothing.
There is also
/proc/acpi/acer/brightness
and if I try
cat /proc/acpi/acer/brightness
I get
8
but the echo command makes no difference.
Any ideas where I'm going wrong?
Jim
Comments
-
How are you attempting to manuall input values into the driver files? ie... echo "7">/sys/class/backlight/acer_acpi/brightness?
I am not the most experieinced with laptops and the brightness functionality, but I will push and learn to try to help you resolve this issue.0 -
Thanks for getting back to me
I try this
sudo echo 7 /sys/class/backlight/acer_acpi/brightness
which, after giving the password, gives me
7 /sys/class/backlight/acer_acpi/brightness
But then, if I check with
cat /sys/class/backlight/acer_acpi/brightness
the answer still comes back as
90 -
The issue you are having with the echo command is because you are using it incorrectly.
The echo command is used to output a string to your terminal, when you enter sudo echo 7 /sys/class/backlight/acer_acpi/brightness is returns everything after the word echo because that is what you are telling it to do.
What wou want to try is sudo echo 7>/sys/class/backlight/acer_acpi/brightness
the 7 is the string that you want to display,
> is telling echo to ouput the display into a file (replacing the file, >> is used to append to a file)
/sys/class/backlight/acer_acpi/brightness is the file which will have it's contents replaced by the ouput of the echo command.
If this works, then we can dive a little deeper and figure out why the buttons are not modifying the values in the perspective files.0 -
Hi
Not very good with the Command Line, me.
I thought that you'd solved it, but I'm afraid it made no difference. I've tried with the different 'brightness' files that I have found and simply get 'Permission Denied' even when I try it as root. Here's a copy:~$ cat /proc/acpi/video/VGA/LCD/brightness levels: 100 80 30 40 50 60 70 80 90 100 current: 100 ~$ echo 40>/proc/acpi/video/VGA/LCD/brightness bash: /proc/acpi/video/VGA/LCD/brightness: Permission denied ~$ sudo echo 40>/proc/acpi/video/VGA/LCD/brightness bash: /proc/acpi/video/VGA/LCD/brightness: Permission denied
However, I can use the function keys on the keyboard to change this value (above), though it has no effect on the actual screen brightness.~$ cat /sys/class/backlight/acer_acpi/brightness 9 ~$ echo 4>/sys/class/backlight/acer_acpi/brightness bash: /sys/class/backlight/acer_acpi/brightness: Permission denied ~$ sudo echo 4>/sys/class/backlight/acer_acpi/brightness bash: /sys/class/backlight/acer_acpi/brightness: Permission denied
And finally...~$ cat /proc/acpi/acer/brightness 6 ~$ echo 2>/proc/acpi/acer/brightness bash: /proc/acpi/acer/brightness: Permission denied ~$ sudo echo 2>/proc/acpi/acer/brightness bash: /proc/acpi/acer/brightness: Permission denied
Jim0 -
Your reponse indicates that those are output files, other files are being used to direct the input to the kernel. Later this evening I will research further to see if I can locate them.0
-
Hi
I haven't had a chance to do an exhaustive test of all of the following, but thought it might be useful to give you the list of files on my system containing the term 'brightness'
file:///etc/acpi/events/asus-brightness-down
file:///etc/acpi/events/asus-brightness-up
file:///etc/acpi/events/panasonic-brightness-down
file:///etc/acpi/events/panasonic-brightness-up
file:///etc/acpi/events/sony-brightness-down
file:///etc/acpi/events/sony-brightness-up
file:///etc/acpi/events/thinkpad-brightness-down
file:///etc/acpi/events/thinkpad-brightness-up
file:///etc/acpi/events/tosh-brightness-down
file:///etc/acpi/events/tosh-brightness-up
file:///etc/acpi/events/video_brightnessdown
file:///etc/acpi/events/video_brightnessup
file:///etc/acpi/resume.d/50-tosh-restore-brightness.sh
file:///etc/acpi/suspend.d/50-tosh-save-brightness.sh
file:///etc/acpi/thinkpad-brightness-down.sh
file:///etc/acpi/thinkpad-brightness-up.sh
file:///etc/acpi/video_brightnessdown.sh
file:///etc/acpi/video_brightnessup.sh
file:///proc/acpi/acer/brightness
file:///proc/acpi/video/OVGA/DD01/brightness
file:///proc/acpi/video/OVGA/DD02/brightness
file:///proc/acpi/video/OVGA/DD03/brightness
file:///proc/acpi/video/OVGA/DD04/brightness
file:///proc/acpi/video/OVGA/DD05/brightness
file:///proc/acpi/video/VGA/CRT/brightness
file:///proc/acpi/video/VGA/HDV0/brightness
file:///proc/acpi/video/VGA/LCD/brightness
file:///proc/acpi/video/VGA/TV/brightness
file:///sys/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/leds/iwl-phy0:assoc/brightness
file:///sys/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/leds/iwl-phy0:radio/brightness
file:///sys/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/leds/iwl-phy0:RX/brightness
file:///sys/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/leds/iwl-phy0:TX/brightness
file:///sys/devices/platform/acer_acpi/backlight/acer_acpi/actual_brightness
file:///sys/devices/platform/acer_acpi/backlight/acer_acpi/brightness
file:///sys/devices/platform/acer_acpi/backlight/acer_acpi/max_brightness
file:///sys/devices/virtual/backlight/acpi_video0/actual_brightness
file:///sys/devices/virtual/backlight/acpi_video0/brightness
file:///sys/devices/virtual/backlight/acpi_video0/max_brightness
file:///sys/devices/virtual/backlight/acpi_video1/actual_brightness
file:///sys/devices/virtual/backlight/acpi_video1/brightness
file:///sys/devices/virtual/backlight/acpi_video1/max_brightness
file:///sys/module/acer_acpi/parameters/brightness
file:///usr/lib/hal/scripts/hal-system-lcd-get-brightness
file:///usr/lib/hal/scripts/hal-system-lcd-set-brightness
file:///usr/lib/hal/scripts/linux/hal-system-lcd-get-brightness-linux
file:///usr/lib/hal/scripts/linux/hal-system-lcd-set-brightness-linux
file:///usr/share/hal/fdi/policy/10osvendor/10-dell-laptop-brightness.fdi
Jim0 -
Have a look at this for your brightness problem.
sudo gedit /usr/share/X11/xorg.conf.d/20-intel.conf
Section "Device"
Identifier "card0"
Driver "intel"
Option "Backlight" "intel_backlight"
BusID "PCI:0:2:0"EndSection
Adding this worked on my Acer Quad core. Can now use
the function key plus arrow keys to increase or
decrease the brightness.0
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