Re: [libgpiod] Some thoughts following a brief test of libgpiod ver 2.1

[Seamus de Mora <seamusdemora@gmail.com>]

On Thu, Dec 28, 2023 at 3:29 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Wed, Dec 27, 2023 at 07:19:54PM -0600, Seamus de Mora wrote:
> > Hello,
> >
> > I've done some testing/evaluation of the 'libgpiod ver 2.1', and I'd
> > like to share a few thoughts from that experience.
> > <snip>

> Then you might want to update your kernel - the kernel device driver was
> changed to support peristing [1].
>
> I get this on my Pi4 running bookworm:
>
> $ gpioset -t0 GPIO23=0
> $ gpioinfo GPIO23
> gpiochip0 23    "GPIO23"                output
> $ gpioget -a GPIO23
> "GPIO23"=inactive
> $ gpioinfo GPIO23
> gpiochip0 23    "GPIO23"                output
> $ gpioset -t0 GPIO23=1
> $ gpioget -a GPIO23
> "GPIO23"=active

Yes - the device driver on my bulleye is current; that change was
committed back in 1Q 2023 IIRC...

I hope I've not already asked this, but:
In ver 1.6.X of libgpiod, gpioset exits immediately, and returns to
the bash prompt. The GPIO line remains set at the value designated
after gpioset exits. AIUI, the driver change from 1Q 2023 was
responsible for this.

In ver 2.1 of libgpiod, gpioset (without options) does not exit. This
means there is no return to the bash prompt. The GPIO line still
remains set at the designated value, so there is no change in the
behavior of the GPIO line between ver 1.6.X and 2.1.

My question is why does the un-optioned gpioset ver 2.1 not exit - as
it did in ver 1.6.X?

Thanks,
~S