Is it okay for me to bump this.

I'm currently debugging my distros powerdevil package, since I'm
unable to run git version. Not a big deal, I can switch sources and
recompile for testing.

However I'm struggling to understand some bits in powerdevilbrightnesslogic.cpp:

#63 in BrightnessLogic::increased:
     int step = m_steps - (m_valueMax - m_value - 1) * m_steps / m_valueMax;
and #81 BrightnessLogic::decreased
     int step = (m_value - 1) * m_steps / m_valueMax;

It looks like a simple ratio equation yet, shouldn't #81 be like
(m_value * m_steps) / m_valueMax - 1;


On 8 February 2018 at 21:09, Ongun Kanat <> wrote:
> It looks like I was wrong. I've ended up copying compiled service
> files into /usr/share/dbus-1 and I still couldn't trigger neither
> backlight notification nor powerdevil.
> dbus-monitor shows no activity either. On my regular plasma desktop I
> can see dbus messages like [1].
> I'm also including my configuration for further info
> [1] dbus-monitor output on my regular plasma 5.12 desktop
> On my git build it is missing.
> [2] system-local.conf symlinked to /etc/dbus-1/system-local.conf
> [3] session-local.conf symlinked to /etc/dbus-1/session-local.conf
> [4] .desktop file for xsession
> [5]
> Any clues?
> -Ongun
> On 8 February 2018 at 02:33, David Edmundson <> 
> wrote:
>> On Wed, Feb 7, 2018 at 10:47 PM, Ongun Kanat <> wrote:
>>> Hello devs,
>>> I'm trying to contribute by fixing a small bug. I'm proficient with
>>> C++ and pretty much used to debug C++ programs with Qt Creator. I've
>>> managed to build full plasma desktop into a directory in my home using
>>> kdesrc-build. and set environment correctly  Now I can launch latest
>>> git version of plasma.
>>> I'm trying to fix a bug in Powerdevil (as i guess):
>>> It looks like a calculation error is being made somewhere but I
>>> couldn't trigger any breakpoint in powerdevil executable. Moreover on
>>> git version of plasma it seems like powerdevil is not be able to get
>>> any sort of brightness signal at all and the kernel's/framebuffer's
>>> standard brightness functionality seems to be triggered. I'm making
>>> this guess since the brightness notification is not being shown. On my
>>> distro's (Arch, pretty vanilla) version of plasma both notification
>>> and powerdevil works and xev displays brightness buttons correctly.
>>> Wandering the installed files in my build directory, I realized kdesrc
>>> have installed dbus-1/system-services folder into the install
>>> directory in my home directory as expected. And there's a dbus service
>>> file called org.kde.powerdevil.backlighthelper.service . I think this
>>> file doesn't get started since it's not in the real /usr/share/dbus-1
>>> folder. Instead the distro's version of it gets started which is
>>> incompatible and is not a part of my git build. Hence, no backlight
>>> signal has been gotten caught and transferred to org.kde.powerdevil
>>> service.
>>> So, my questions are:
>>> - Is my reasoning correct?
>> Certainly the part about it loading the distro version.
>> No idea about whether it's compatiable or not.
>>> - If it's, is there any clean way to force dbus to launch the files in
>>> my build directory instead of /usr. Using an environment variable
>>> would be nice
>> Session bus, yes.
>> System bus, not really. The problem is because it's run as root it's locked
>> down its paths for security. You can't just randomly source other places
>> You'll also have an equivalent problem with polkit actions and rules files
>> which you need here.
>> You can modify system.conf  to add an include dir, but you'll need to do
>> that as root in your system supplied config file.
>> I haven't found a good solution for the polkit problem without just adding
>> symlinks.
>> David

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