changing screen brightness broken in Xubuntu (12.04 and 14.04)

[Liviu Andronic]

On Sun, Apr 27, 2014 at 4:35 AM, Damian Kleiman <fliakleiman at gmail.com> wrote:
> My brightness also stopped working on my last update, but i fixed it
> by using the following command to make it brighter:
>
> xgamma -gamma 1
>
> I tried several numbers between 0 and 1 (0.25, 0.5, etc) and i
> prefered one on my laptop.
>
Having read from man xgamma that "Note that the xgamma utility is
obsolete and deficient, xrandr should
be used with drivers that support the XRandr extension.", I decided to
check out man xrandr. Then following
http://askubuntu.com/questions/45153/is-there-an-alternative-to-redshift-and-f-lux-which-only-dims-the-screen/48952#48952
, the below works perfectly fine on my laptop:

xrandr --output eDP1 --brightness 0.2

So it seems to me that the hardware issue, if it actually exists, can
be worked around. Should I report this brightness issue more formally
on Launchpad?

Regards,
Liviu

> Regards,
> Damian
>
> 2014-04-26 21:26 GMT-03:00 Liviu Andronic <landronimirc at gmail.com>:
>> 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?
>>>> http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail
>>>>
>>>> --
>>>> xubuntu-devel mailing list
>>>> xubuntu-devel at lists.ubuntu.com
>>>> https://lists.ubuntu.com/mailman/listinfo/xubuntu-devel
>>>
>>>
>>>
>>> --
>>> xubuntu-devel mailing list
>>> 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
>>
>> --
>> xubuntu-devel mailing list
>> xubuntu-devel at lists.ubuntu.com
>> https://lists.ubuntu.com/mailman/listinfo/xubuntu-devel
>
> --
> xubuntu-devel mailing list
> 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