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Date:   Wed, 4 Nov 2020 20:04:08 +0100
From:   Maxime Ripard <maxime@cerno.tech>
To:     Matteo Scordino <matteo.scordino@gmail.com>
Cc:     wens@csie.org, robh+dt@kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/6] ARM: dts: sun8i: s3: Add dtsi for the Elimo
 Impetus SoM
Message-ID: <20201104190408.krxoqm2fei3kboud@gilmour.lan>
References: <20201029022000.601913-1-matteo.scordino@gmail.com>
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Hi

On Tue, Nov 03, 2020 at 04:28:27PM +0000, Matteo Scordino wrote:
> --=20
> Matteo Scordino / Embedded Software Consultant
> Mobile: +44 (0)7463701446
>=20
> On Mon, 2020-11-02 at 11:05 +0100, Maxime Ripard wrote:
> > Hi!
> >=20
> > On Fri, Oct 30, 2020 at 11:43:22PM +0000, Matteo Scordino wrote:
> > > The Elimo Engineering Impetus is an Open Source Hardware System-on-Mo=
dule
> > > based on the SoChip S3 SoC.
> > >=20
> > > It is meant for integration into carrier boards or, more generally,
> > > larger designs, and uses an M2 connector to facilitate that.
> > >=20
> > > Interfaces on the M.2/NGFF 42mm connector:
> > > WiFi IEEE 802. 11abgn (on-module Realtek)
> > > Bluetooth 4.2/BLE (on-module Realtek)
> > > RGB LCD Interface (on-module connector)
> > > MIPI Camera Interface (on-module connector)
> > > IEEE 802. 3u Ethernet MAC (external connecto)
> > > USB2.0 (Host, Device, OTG) (external connector)
> > > Audio Line In/Out (external connector)
> > >=20
> > > Signed-off-by: Matteo Scordino <matteo.scordino@gmail.com>
> > > ---
> > >  arch/arm/boot/dts/sun8i-s3-elimo-impetus.dtsi | 51 +++++++++++++++++=
++
> > >  1 file changed, 51 insertions(+)
> > >  create mode 100644 arch/arm/boot/dts/sun8i-s3-elimo-impetus.dtsi
> > >=20
> > > diff --git a/arch/arm/boot/dts/sun8i-s3-elimo-impetus.dtsi b/arch/arm=
/boot/dts/sun8i-s3-elimo-impetus.dtsi
> > > new file mode 100644
> > > index 000000000000..f219188fc9ba
> > > --- /dev/null
> > > +++ b/arch/arm/boot/dts/sun8i-s3-elimo-impetus.dtsi
> > > @@ -0,0 +1,51 @@
> > > +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> > > +/*
> > > + * Copyright (C) 2020 Matteo Scordino <matteo@elimo.io>
> > > + */
> > > +
> > > +/dts-v1/;
> > > +#include "sun8i-v3.dtsi"
> > > +#include "sunxi-common-regulators.dtsi"
> > > +
> > > +/ {
> > > +	model =3D "Elimo Impetus SoM";
> > > +	compatible =3D "elimo,impetus", "sochip,s3", "allwinner,sun8i-v3";
> > > +
> > > +	aliases {
> > > +		serial0 =3D &uart0;
> > > +		serial1 =3D &uart1;
> > > +	};
> > > +
> > > +	chosen {
> > > +		stdout-path =3D "serial0:115200n8";
> > > +	};
> > > +};
> > > +
> > > +&mmc0 {
> > > +	broken-cd;
> > > +	bus-width =3D <4>;
> > > +	vmmc-supply =3D <&reg_vcc3v3>;
> > > +	status =3D "okay";
> > > +};
> > > +
> > > +&uart0 {
> > > +	pinctrl-0 =3D <&uart0_pb_pins>;
> > > +	pinctrl-names =3D "default";
> > > +	status =3D "okay";
> > > +};
> > > +
> > > +&uart1 {
> > > +	pinctrl-0 =3D <&uart1_pg_pins>;
> > > +	pinctrl-names =3D "default";
> > > +	status =3D "okay";
> > > +};
> >=20
> > What is uart1 used for? the BT chip?
> >=20
> > Maxime
>=20
> No, BT is provided over SDIO by a Cypress 43455.
> When used with the Initium carrier board, UART1 goes to an FTDI bridge th=
at is
> connected to the same USB-C connector that is used for power.
> The idea being, if want an application that uses the UART to communicate =
with a
> PC, it's convenient to provide power+connectivity on a single port.
>=20
> I guess your point is that we would be better off only defining this in t=
he DTS
> of the carrier board?

I wasn't trying to make any point, it was a legitimate question, we
don't want to enable something that is optional or could be used for
something else (like a UART exposed on a generic pin header).

But from what you're telling me, yeah, it should be moved to the
daughter board DTS.

Maxime


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