Date:   Mon, 7 Jun 2021 15:53:23 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Jernej Škrabec <jernej.skrabec@...il.com>,
        Anup Patel <anup.patel@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Arnd Bergmann <arnd@...db.de>, Chen-Yu Tsai <wens@...e.org>,
        Drew Fustini <drew@...gleboard.org>, liush@...winnertech.com,
        Wei Wu (吴伟) <lazyparser@...il.com>,
        wefu@...hat.com, linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-sunxi@...ts.linux.dev, Guo Ren <guoren@...ux.alibaba.com>,
        Atish Patra <atish.patra@....com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [RFC PATCH v2 09/11] riscv: soc: Initial DTS for Allwinner D1
 NeZha board

Thx for the clarification.

On Mon, Jun 7, 2021 at 3:27 PM Maxime Ripard <maxime@...no.tech> wrote:
>
> On Mon, Jun 07, 2021 at 11:44:03AM +0800, Guo Ren wrote:
> > On Mon, Jun 7, 2021 at 12:26 AM Jernej Škrabec <jernej.skrabec@...il.com> wrote:
> > >
> > > Hi!
> > >
> > > I didn't go through all details. After you fix all comments below, you should
> > > run "make dtbs_check" and fix all reported warnings too.
> > >
> > > Dne nedelja, 06. junij 2021 ob 11:04:07 CEST je guoren@...nel.org napisal(a):
> > > > From: Guo Ren <guoren@...ux.alibaba.com>
> > > >
> > > > Add initial DTS for Allwinner D1 NeZha board having only essential
> > > > devices (uart, dummy, clock, reset, clint, plic, etc).
> > > >
> > > > Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> > > > Co-Developed-by: Liu Shaohua <liush@...winnertech.com>
> > > > Signed-off-by: Liu Shaohua <liush@...winnertech.com>
> > > > Cc: Anup Patel <anup.patel@....com>
> > > > Cc: Atish Patra <atish.patra@....com>
> > > > Cc: Christoph Hellwig <hch@....de>
> > > > Cc: Chen-Yu Tsai <wens@...e.org>
> > > > Cc: Drew Fustini <drew@...gleboard.org>
> > > > Cc: Maxime Ripard <maxime@...no.tech>
> > > > Cc: Palmer Dabbelt <palmerdabbelt@...gle.com>
> > > > Cc: Wei Fu <wefu@...hat.com>
> > > > Cc: Wei Wu <lazyparser@...il.com>
> > > > ---
> > > >  arch/riscv/boot/dts/Makefile                       |  1 +
> > > >  arch/riscv/boot/dts/allwinner/Makefile             |  2 +
> > > >  .../boot/dts/allwinner/allwinner-d1-nezha-kit.dts  | 29 ++++++++
> > > >  arch/riscv/boot/dts/allwinner/allwinner-d1.dtsi    | 84
> > > > ++++++++++++++++++++++ 4 files changed, 116 insertions(+)
> > > >  create mode 100644 arch/riscv/boot/dts/allwinner/Makefile
> > > >  create mode 100644 arch/riscv/boot/dts/allwinner/allwinner-d1-nezha-kit.dts
> > > > create mode 100644 arch/riscv/boot/dts/allwinner/allwinner-d1.dtsi
> > > >
> > > > diff --git a/arch/riscv/boot/dts/Makefile b/arch/riscv/boot/dts/Makefile
> > > > index fe996b8..3e7b264 100644
> > > > --- a/arch/riscv/boot/dts/Makefile
> > > > +++ b/arch/riscv/boot/dts/Makefile
> > > > @@ -2,5 +2,6 @@
> > > >  subdir-y += sifive
> > > >  subdir-$(CONFIG_SOC_CANAAN_K210_DTB_BUILTIN) += canaan
> > > >  subdir-y += microchip
> > > > +subdir-y += allwinner
> > > >
> > > >  obj-$(CONFIG_BUILTIN_DTB) := $(addsuffix /, $(subdir-y))
> > > > diff --git a/arch/riscv/boot/dts/allwinner/Makefile
> > > > b/arch/riscv/boot/dts/allwinner/Makefile new file mode 100644
> > > > index 00000000..4adbf4b
> > > > --- /dev/null
> > > > +++ b/arch/riscv/boot/dts/allwinner/Makefile
> > > > @@ -0,0 +1,2 @@
> > > > +# SPDX-License-Identifier: GPL-2.0
> > > > +dtb-$(CONFIG_SOC_SUNXI) += allwinner-d1-nezha-kit.dtb
> > > > diff --git a/arch/riscv/boot/dts/allwinner/allwinner-d1-nezha-kit.dts
> > > > b/arch/riscv/boot/dts/allwinner/allwinner-d1-nezha-kit.dts new file mode
> > > > 100644
> > > > index 00000000..cd9f7c9
> > > > --- /dev/null
> > > > +++ b/arch/riscv/boot/dts/allwinner/allwinner-d1-nezha-kit.dts
> > >
> > > Board DT names are comprised of soc name and board name, in this case it would
> > > be "sun20i-d1-nezha-kit.dts"
> > >
> > > > @@ -0,0 +1,29 @@
> > > > +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> > >
> > > Usually copyrights are added below spdx id.
> > >
> > > > +
> > > > +/dts-v1/;
> > > > +
> > > > +#include "allwinner-d1.dtsi"
> > > > +
> > > > +/ {
> > > > +     #address-cells = <2>;
> > > > +     #size-cells = <2>;
> > >
> > > This should be part of SoC level DTSI.
> > >
> > > > +     model = "Allwinner D1 NeZha Kit";
> > > > +     compatible = "allwinner,d1-nezha-kit";
> > >
> > > Board specific compatible string should be followed with SoC compatible, in
> > > this case "allwinner,sun20i-d1".  You should document it too.
> > >
> > > > +
> > > > +     chosen {
> > > > +             bootargs = "console=ttyS0,115200";
> > >
> > > Above line doesn't belong here. If anything, it should be added dynamically by
> > > bootloader.
> >
> > After discussion, we still want to keep a default value here.
> > Sometimes we could boot with jtag and parse dtb is hard for gdbinit
> > script.
> >
> > >
> > > > +             stdout-path = &serial0;
> > > > +     };
> > > > +
> > > > +     memory@...00000 {
> > > > +             device_type = "memory";
> > > > +             reg = <0x0 0x40000000 0x0 0x20000000>;
> > > > +     };
> > >
> > > Ditto for whole memory node.
> >
> > Ditto
>
> The thing is that there's never a good value for a default. Let's take
> the memory node here: what would be a good default? If we want to make
> it work everywhere it's going to be the lowest amount of memory
> available on the D1 boards. It's going to be hard to maintain and very
> likely to be overlooked, resulting in broken boards anyway.
>
> If someone is savvy enough to use JTAG, it's not really difficult to
> modify the DT for their board when they need it.
okay, I see. I'll follow the rule in the next version of the patchset.

>
> Maxime



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

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