linux-kernel - Re: [PATCH 02/14] dt-bindings: serial: Document sci bindings for the Renesas RZ/T2H (a.k.a r9a09g077) SoC

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Message-ID: <CAMuHMdUpaV71Svyenq=hXMk3GfjgZvHn-0APkv_LKSzyytKzag@mail.gmail.com>
Date: Mon, 10 Feb 2025 15:15:10 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Thierry Bultel <thierry.bultel.yh@...renesas.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 02/14] dt-bindings: serial: Document sci bindings for the
 Renesas RZ/T2H (a.k.a r9a09g077) SoC

Hi Biju,

On Mon, 10 Feb 2025 at 14:19, Biju Das <biju.das.jz@...renesas.com> wrote:
> > -----Original Message-----
> > From: Geert Uytterhoeven <geert@...ux-m68k.org>
> > Sent: 10 February 2025 13:15
> > Subject: Re: [PATCH 02/14] dt-bindings: serial: Document sci bindings for the Renesas RZ/T2H (a.k.a
> > r9a09g077) SoC
> >
> > On Wed, 29 Jan 2025 at 17:52, Thierry Bultel <thierry.bultel.yh@...renesas.com> wrote:
> > > Document RZ/T2H (a.k.a r9a09g077) in SCI binding.
> > >
> > > Signed-off-by: Thierry Bultel <thierry.bultel.yh@...renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/serial/renesas,rzsci.yaml
> > > @@ -0,0 +1,100 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/serial/renesas,rzsci.yaml#
> >
> > "rzsci" is IMHO a bad name, as SCI on RZ/T2 differs from the similar-named "SCI" (sometimes called
> > "RSCI" or "SCIg") on RZ/A1H, RZ/A2M, RZ/G2L, RZ/V2L, and RZ/G3S (and most old SuperH SoCs).
> >
> > BTW, I believe the variant on RZ/T2 is also used on RZ/N2, RZ/V2H, and RZ/G3E?
> >
> > However, binding-wise, they all seem to be very similar.
> > So perhaps you can just add this to the existing
> > Documentation/devicetree/bindings/serial/renesas,sci.yaml?
>
> It is present in RZ/G3E as well.
> RSCI supports sci, scif, i2c and spi that is the reason renesas,rzsci.yaml introduced.

If you plan to add support for I2C and SPI, you will need different
bindings under Documentation/devicetree/bindings/{i2c,spi}/.

Note that we already have drivers/spi/spi-sh-sci.c (without DT support),
but it's definitely sub-optimal for the fancy new variant in RZ/T2...

> You mean add this in renesas,sci.yaml and then expand??

Indeed. Differences seem to be minimal.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds