> > > > > 2 - Hardware key that does not control the hardware radio and does not report anything to userspace
> > > >
> > > > Kind of uninteresting button ;)
> > >
> > > And this is the button that rfkill was originally designed for.
> > > Laptops with integrated WiFi cards from Ralink have a hardware button that don't send anything to
> > > userspace (unless the ACPI event is read) and does not directly control the radio itself.
> > >
> >
> > So what does such a button do? I am confused here...
>
> Without a handler like rfkill, it does nothing besides toggling a bit in a register.
> The Ralink chipsets have a couple of registers that represent the state of that key.
> Besides that, there are no notifications to the userspace nor does it directly control the
> radio.
> That is where rfkill came in with the toggle handler that will listen to the register
> to check if the key has been pressed and properly process the key event.
In this case the driver can make the button state available to userspace so
thsi is really type 2) driver as far as I can see. The fact that the button
is not reported to userspace yet should not get into our way of classifying
it.