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Date: Fri, 23 Feb 2024 08:47:33 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	"lee@kernel.org" <lee@kernel.org>,
	"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Linux support for a 7 segment LED display
Message-ID: <ZdhNlUotGJCklJTs@duo.ucw.cz>
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Hi!

> > Right, but also with some additional properties, like
> > - type of the indicator (7, 14, etc segments, for now we have only
> > these two supported)
> > - use-dot (+1 led per each digit)
> > - characters (how many digits we have, so we need respective amount of =
GPIOs)
> >
> > With this it's indeed belongs directly to auxdisplay as we have almost
> > everything is done already there.
>=20
> I've been playing about with this. I've got an auxdisplay driver that's=
=20
> basically working (I won't bother spamming list with it yet). But I'm=20
> wondering how I'd represent multiple characters. I kind of feel the=20
> natural representation would be something like.
>=20
>  =A0=A0=A0=A0=A0=A0=A0 led-7seg {
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 compatible =3D "generic,7-=
segment-on-gpio";
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 char-0 {
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0=A0 segment-gpios =
=3D <&gpio 0 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 =A0=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 &gpio 1 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =
=A0=A0 =A0 =A0=A0=A0=A0=A0=A0=A0 &gpio 2 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0 =A0=A0 =A0 =A0=A0=A0 &gpio 3 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 &gpio 4 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0=A0 &gpio 5 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 &gpio 6 GPIO_ACTIVE_LOW>;
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 };
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 char-1 {
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0=A0 segment-gpios =
=3D <&gpio 8 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 =A0=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 &gpio 9 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 =
=A0=A0 =A0 =A0=A0=A0=A0=A0=A0=A0 &gpio 10 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0 =A0=A0 =A0 =A0=A0=A0 &gpio 11 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 &gpio 12 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 =A0=A0=A0 &gpio 13 GPIO_ACTIVE_LOW
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0 =A0=A0 =A0 &gpio 14 GPIO_ACTIVE_LOW>;
>  =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 };
>  =A0=A0=A0=A0=A0=A0=A0 };
>=20
> But having those sub-nodes means I can't just use devm_gpiod_get_array()=
=20
> instead I'd have to use device_for_each_child_node() and=20
> devm_fwnode_gpiod_get_index(). Am I missing something? I could do away=20
> with the sub-nodes and have properties like "segment-0-gpios",=20
> "segment-1-gpios" but that feels awkward.

One solution would be to treat separate digits as separata devices
:-).

Other would be saying you don't have hardware for that, and make it
someone else's future problem.

Best regards,
								Pavel
--=20
People of Russia, stop Putin before his war on Ukraine escalates.

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