Xorg framebuffer and brightness of screen

[Riza Dindir]

Thank you for very much for the information. Was thinking that playing with
the gamma might be a solution.

Regards.
Riza

On Mon, Nov 15, 2021, 19:33 Alex Deucher <alexdeucher at gmail.com> wrote:

> On Fri, Nov 12, 2021 at 11:21 PM Riza Dindir <riza.dindir at gmail.com>
> wrote:
> >
> > Hello Alex,
> >
> > Isn't there a software based solution to set the brightness in xorg?
>
> Not really.  You need some interface to talk to the backlight
> controller, either via software via a driver or via some firmware
> interface like ACPI if the platform supports it.  You can also adjust
> the gamma on the display which will give the perception of changes in
> brightness, but it won't actually change the levels of the backlight
> itself.  That said, you need driver support to adjust the gamma as
> well.
>
> Alex
>
> >
> > Riza
> >
> > On Fri, Nov 12, 2021 at 11:37 PM Alex Deucher <alexdeucher at gmail.com>
> wrote:
> > >
> > > On Fri, Nov 12, 2021 at 12:36 AM Riza Dindir <riza.dindir at gmail.com>
> wrote:
> > > >
> > > > Hello Ken.
> > > >
> > > > On Fri, Nov 12, 2021 at 12:56 AM Ken Moffat <zarniwhoop at ntlworld.com>
> wrote:
> > > > >
> > > > > On Thu, Nov 11, 2021 at 10:16:18AM +0300, Riza Dindir wrote:
> > > > > > Hello Ken
> > > > > >
> > > > > > I am using gop, and a framebuffer. When i try to use the xrandr,
> it says
> > > > > > "gamma is set to 0", or "failed to get size of gamma for output
> default".
> > > > > >
> > > > > > I can set the gamma uaing xgamma and in the xorg.conf file.
> > > > > >
> > > > > > Riza
> > > > > >
> > > > > No idea what gop is - google suggests it's the american republican
> > > > > party ;-)
> > > >
> > > > :D That is the graphics output protocol.
> > > >
> > > > My radeon device is not recognized by the kernel (netbsd) and I am
> > > > using a framebuffer.
> > > >
> > > > >
> > > > > Did you search for that "failed to get" message ?  Google gives me
> a lot of
> > > > > different matches, some for failing to correctly add a new mode,
> > > > > others for running with nvidia drivers or in virtualbox, or with
> out
> > > > > of date manufacturer's video driver.
> > > > >
> https://askubuntu.com/questions/441040/failed-to-get-size-of-gamma-for-output-default-when-trying-to-add-new-screen-res
> > > > >
> > > > > For an ubuntu-based kernel with at-the-time recent intel graphics
> > > > > hardware, adding a boot arg to enable alpha-quality intel support.
> > > > >
> https://itectec.com/ubuntu/ubuntu-xrandr-failed-to-get-size-of-gamma-for-output-default-for-mdp-type-connection/
> > > > >
> > > > > In short, finding the answer really does seem to depend on what
> > > > > hardware and distro are in use.  I'm assuming you're using some
> sort
> > > > > of linux.
> > > >
> > > > What I am trying to do is reduce the brightness of the LCD on my
> > > > laptop. Since I am using a framebuffer, I thought that I could do
> that
> > > > with the gamma values. But xrandr fails with  a message relating to
> > > > the gamma values being 0 or not set.
> > >
> > > You might get lucky if your system supports backlight control via
> > > hotkeys or some ACPI interface which your BSD supports.  If not, then
> > > not.  There's no backlight control in GOP.
> > >
> > > Alex
> > >
> > >
> > > >
> > > > >
> > > > > ĸen
> > > > > --
> > > > > Vetinari smiled. "Can you keep a secret, Mister Lipwig?"
> > > > > "Oh, yes, sir. I've kept lots."
> > > > > "Capital. And the point is, so can I. You do not need to know.”
> > > >
> > > > Regards,
> > > > Riza
>
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