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From:   Rob Herring <robh+dt@kernel.org>
Date:   Fri, 18 Nov 2022 15:23:47 -0600
Message-ID: <CAL_JsqJzM9y4pbN9UQpNENm9fB7-jGcch6n4w98eBuidL9rNsw@mail.gmail.com>
Subject: Re: [RFC v3 11/11] arm64: dts: mt7986: add BPI-R3 nand/nor overlays
To:     Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Frank Wunderlich <linux@fw-web.de>,
        linux-mediatek@lists.infradead.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Frank Wunderlich <frank-w@public-files.de>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Fri, Nov 11, 2022 at 3:16 AM Matthias Brugger <matthias.bgg@gmail.com> wrote:
>
> Rob, Krzysztof,
>
> On 06/11/2022 09:50, Frank Wunderlich wrote:
> > From: Frank Wunderlich <frank-w@public-files.de>
> >
> > Add devicetree overlays for using nand and nor on BPI-R3.

Overlays are necessary because ...?

> > Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> > ---
> >   arch/arm64/boot/dts/mediatek/Makefile         |  2 +
> >   .../mediatek/mt7986a-bananapi-bpi-r3-nand.dts | 53 +++++++++++++++
> >   .../mediatek/mt7986a-bananapi-bpi-r3-nor.dts  | 67 +++++++++++++++++++
> >   3 files changed, 122 insertions(+)
> >   create mode 100644 arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3-nand.dts
> >   create mode 100644 arch/arm64/boot/dts/mediatek/mt7986a-bananapi-bpi-r3-nor.dts
> >
> > diff --git a/arch/arm64/boot/dts/mediatek/Makefile b/arch/arm64/boot/dts/mediatek/Makefile
> > index e8902f2cc58f..d42208c4090d 100644
> > --- a/arch/arm64/boot/dts/mediatek/Makefile
> > +++ b/arch/arm64/boot/dts/mediatek/Makefile
> > @@ -8,6 +8,8 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += mt6797-x20-dev.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt7622-rfb1.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt7622-bananapi-bpi-r64.dtb
> >   dtb-$(CONFIG_ARCH_MEDIATEK) += mt7986a-bananapi-bpi-r3-emmc.dtb
> > +dtb-$(CONFIG_ARCH_MEDIATEK) += mt7986a-bananapi-bpi-r3-nand.dtbo
> > +dtb-$(CONFIG_ARCH_MEDIATEK) += mt7986a-bananapi-bpi-r3-nor.dtbo
>
> Do we allow the inclusion of overlays in the kernel?
> I don't think so. I see there are some dtbos for some freescale platforms, but I
> wasn't aware that we support that. I thought it is all about dtsi includes.

Yes, we do.

> @frank In any case we would need to apply these overlays to some base board to
> create a valis dtb.

Indeed. The build system supports this and it's a requirement (though
not easily enforced) that overlays apply to something. It works much
like how kbuild combines multiple .o files into a module.

Please rename to .dtso though. I copied you all on the PR I just sent.

Rob