Can't adjust brightness after upgrade

[ohmy28]

I just upgraded and now I can't adjust brightness. I've tried changing my grub to:

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"
GRUB_CMDLINE_LINUX=""

and

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

That I've seen suggested. Any idea what to do?

[Toz]

Did you upgrade to raring (13.04)?

What is the make and model of your computer?

Perhaps post back your dmesg log file for review:

pastebinit /var/log/dmesg

...and post back the link that is generated.

[ohmy28]

Sorry about that. Yaah, I upgraded to 13.04. I have a Gateway NV55C , and here's the link: http://paste.ubuntu.com/5607130/

[Toz]

When you say that you can't adjust brightness, do you mean via the FN+ brightness keys? If so, it would be interesting to see whether its the brightness that doesn't work, or the function keys. Try this.

The following command will identify your backlight interfaces and their current values:

grep . /sys/class/backlight/*/*

...and you should see something like this:

$ grep . /sys/class/backlight/*/*
/sys/class/backlight/intel_backlight/actual_brightness:1044
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:1044
grep: /sys/class/backlight/intel_backlight/device: Is a directory
/sys/class/backlight/intel_backlight/max_brightness:3484
grep: /sys/class/backlight/intel_backlight/power: Is a directory
grep: /sys/class/backlight/intel_backlight/subsystem: Is a directory
/sys/class/backlight/intel_backlight/type:raw

"brightness" is the current brightness value. "max_brightness" is the maximum value that your backlight interface can handle. Try manually changing the brightness value to see if the brightness changes:

echo XX | sudo tee /sys/class/backlight/YY/brightness

...where XX is a value between 0 and "max_brightness" and YY is the backlight interface directory (in my case, intel_backlight).

You might also want to try some other kernel parameters. First, try without acpi_backlight=vendor:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

Then try the following combinations:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=Linux acpi_backlight=vendor"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi="

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=\"!Windows 2012\""

Make sure to run:

sudo update-grub

...after each change to /etc/default/grub and rebooting.

[ohmy28]

Ok, so these worked:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=Linux acpi_backlight=vendor"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi="

But it only works with the Fn keys. If I use the slider on System Settings, it wont adjust.

I didn't understand much of the

grep . /sys/class/backlight/*/*

So I'll include it, hopefully you'll understand more of it.

maxo@Dayman:~$ grep . /sys/class/backlight/*/*
/sys/class/backlight/acpi_video0/actual_brightness:9
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:9
grep: /sys/class/backlight/acpi_video0/device: Is a directory
/sys/class/backlight/acpi_video0/max_brightness:9
grep: /sys/class/backlight/acpi_video0/power: Is a directory
grep: /sys/class/backlight/acpi_video0/subsystem: Is a directory
/sys/class/backlight/acpi_video0/type:firmware
/sys/class/backlight/intel_backlight/actual_brightness:976
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:976
grep: /sys/class/backlight/intel_backlight/device: Is a directory
/sys/class/backlight/intel_backlight/max_brightness:976
grep: /sys/class/backlight/intel_backlight/power: Is a directory
grep: /sys/class/backlight/intel_backlight/subsystem: Is a directory
/sys/class/backlight/intel_backlight/type:raw

Edit: Using the Fn Keys, you can only adjust it a little, like from full brightness to about half.

[Toz]

maxo@Dayman:~$ grep . /sys/class/backlight/*/*
/sys/class/backlight/acpi_video0/actual_brightness:9
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:9
grep: /sys/class/backlight/acpi_video0/device: Is a directory
/sys/class/backlight/acpi_video0/max_brightness:9
grep: /sys/class/backlight/acpi_video0/power: Is a directory
grep: /sys/class/backlight/acpi_video0/subsystem: Is a directory
/sys/class/backlight/acpi_video0/type:firmware
/sys/class/backlight/intel_backlight/actual_brightness:976
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:976
grep: /sys/class/backlight/intel_backlight/device: Is a directory
/sys/class/backlight/intel_backlight/max_brightness:976
grep: /sys/class/backlight/intel_backlight/power: Is a directory
grep: /sys/class/backlight/intel_backlight/subsystem: Is a directory
/sys/class/backlight/intel_backlight/type:raw

You have 2 backlight interfaces (intel_backlight and acpi_video0). Do any of those kernel boot parameters result in only one backlight interface? Maybe you could also try:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=Linux"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi= acpi_backlight=vendor"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi='!Windows 2012'"

[ohmy28]

None of the boot parameters resulted in just one interface. But,

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX="acpi_osi='!Windows 2012'"

Made it so I wasn't able to change brightness. To add something else, with the other parameters when I adjust with the Fn Keys, the brightness bubble you get on the top right of your screen doesn't appear, but with the one that doesn't allow me to change brightness it does.

[Toz]

On a hunch....

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi='!Windows 2012' acpi_backlight=vendor"

[ohmy28]

No luck

[Toz]

Ok, so these worked:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi=Linux acpi_backlight=vendor"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_osi="

But it only works with the Fn keys. If I use the slider on System Settings, it wont adjust.

Looks like these are the ones that work best. Might be a good idea to create a bug report.