[Buildroot] [PATCH 1/1] package/gpiod: add gpiod hardware handling daemon

Alexander Dahl post at lespocky.de
Sat Jun 20 12:33:40 UTC 2020

Hei hei,

On Fri, Jun 19, 2020 at 10:25:52PM +0200, Marc Chalain wrote:
> Le ven. 19 juin 2020 à 21:39, Alexander Dahl <post at lespocky.de> a écrit :
> > However, I defined my button in dts as key, not just as gpio, because
> > it is actually a key and linux has infrastructure for that.
> > Furthermore there are reliable userspace libraries to not reinvent the
> > wheel. I was able to build something around libevdev in two days.
> >
> This solution may be complicated when you use some buttons for an
> application,
> and just another button for a system feature. You have to manage several
> keyboards,
>  to name each one by udev (or mdev) to use the good one with each
> application.

No and no.

There's no keyboard involved, the keycode I used is not even assigned
to a key usually found on keyboards. The system has neither udev nor
mdev, the key is ready by just defining it in dts.

> A daemon on GPIO will never replace a keyboard. When you need several
> events
> key and a short time response, a keyboard is more powerful.
> The Daemon is useful for few events in the life of the system, and you
> don't want
> modify an application.

This is exactly my usecase, a tiny daemon doing basically nothing but
waiting for a button press once a year or so.

> > Besides: your gpiod uses the well known libgpiod, but is not part of
> > that project, right? That is a little puzzling, people will mix that
> > up.
> >
> Yes I'm sorry for the name. I wanted to use direct access to the
> /dev/gpiochip,
> and after I saw that libgpiod was a kernel.org project. I should change the
> name
> but it's the right name for its usage, and it uses libgpiod, then the
> daemon promotes
> the library. Another name would have been stupid.
> I will propose the daemon to the libgpiod developer, when I will be ready.

Looking forward to that. :-)


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