xrandr brightness settings permanent

[Riccardo Berto]

On 2018-11-14 15:10, Michal Srb wrote:
> On středa 14. listopadu 2018 10:52:59 CET Riccardo Berto wrote:
>> I have a low quality screen. It's very bright, even at minimum 
>> settings
>> in the monitor menu. I'm able to reduce the brightness with `xrandr
>> --output HDMI-0 --brightness 0.25` but sometimes the brightness goes
>> back to the default levels when downloading something from the browser
>> or doing peculiar interactions with the Xorg server, like opening the
>> file manager. I guess this is caused by a re-read of the xorg.conf 
>> file
>> under certain circumstances that I'm not aware of.
>> The question is: is it possible to make the previously mentioned 
>> xrandr
>> command permanent via some /etc/X11/xorg.conf.d/ conf file?
> 
> The xrandr's brightness parameter is just a multiplier for gamma, so 
> you
> should be able to achieve the same thing with configuration like this:
> 
> Section "Monitor"
>   ...
> 
>   Gamma 0.25
> EndSection
> 
> This is alternative way of setting the initial value instead of using 
> xrandr,
> but it probably won't fix the random changing back at runtime. X server 
> does
> not normally reload xorg.conf while it is running. It seems that some
> application is intentionally changing the gamma at runtime, you should 
> try to
> find out which one it is. Maybe some color management app? Don't you 
> have
> redshift installed?
> 
> Michal

Thanks for the answer.
No, I don't use redshift. As far as I know, it can only happen twice 
during each Xorg start up. After these 2 times and me readjusting the 
backlight manually with the xrandr command previously posted, it stays 
that way even for a week of continued usage. It has done that for years. 
In the meantime I changed browsers, usage habits, Xorgs versions, PCs, 
GPUs, drivers, ...
I have a keyboard shortcut with that xrandr command saved for this exact 
reason as I have to execute it up to 3 times during each session. I 
finally decided to go public with this issue as I can hardly bare the 
default minimum brightness of my "new" subpar screen.