changing screen brightness broken in Xubuntu (12.04 and 14.04)

[Liviu Andronic]

On Sat, Apr 26, 2014 at 10:26 AM, PK <pliniusminor at gmail.com> wrote:
> Try this:
> https://sites.google.com/site/easylinuxtipsproject/display#TOC-Brightness-of-the-display-is-wrong-and-not-adjustable
>
> Those tweaks work fine on my machines. :-)
>
> Not really a Linux error, this; it has to do with BIOS / UEFI that's not
> standard-compliant.
>
Thanks for the tips, but unfortunately none worked for me. I tried
several workarounds.
- with no obvious success:
GRUB_CMDLINE_LINUX="acpi_osi=Linux"

and
update-grub

- the following has no effect:
xbacklight -set 20

- and neither does this help:
root at liv-inspiron:/home/geek# lspci | grep -i vga
00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT
Integrated Graphics Controller (rev 09)
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc.
[AMD/ATI] Venus PRO [Radeon HD 8850M] (rev ff)
root at liv-inspiron:/home/geek# setpci -s 00:02.0 F4.B=20
root at liv-inspiron:/home/geek# setpci -s 03:00.0 F4.B=20


Any ideas on what else could be wrong? Thanks,
Liviu

> Regards, Pjotr.
>
>
> 2014-04-26 9:56 GMT+02:00 Liviu Andronic <landronimirc at gmail.com>:
>>
>> Dear all,
>> For several releases now (12.04 and 14.04) and across several machines
>> (Lenovo 32-bit and Dell 64-bit), changing brightness settings is
>> broken. It doesn't work whether I use the laptop buttons to modify
>> screen brightness (to get the notification changing the percentage,
>> but actual brightness NOT move one bit) or the Brightness panel-plugin
>> from xfce4-power-manager (nothing really happens).
>>
>> Is this a known issue (or should I report it to Launchpad)? But more
>> importantly, how can I change screen brightness in Xubuntu (install
>> gnome-power-manager, etc.)?
>>
>> Regards,
>> Liviu
>>
>> --
>> Do you know how to read?
>> http://www.alienetworks.com/srtest.cfm
>> http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
>> Do you know how to write?
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>>
>> --
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>> xubuntu-devel at lists.ubuntu.com
>> https://lists.ubuntu.com/mailman/listinfo/xubuntu-devel
>
>
>
> --
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> xubuntu-devel at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/xubuntu-devel
>



-- 
Do you know how to read?
http://www.alienetworks.com/srtest.cfm
http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
Do you know how to write?
http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail