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From:   Rob Herring <robh+dt@kernel.org>
Date:   Fri, 18 Nov 2022 15:45:54 -0600
Message-ID: <CAL_JsqLdfWaP7aX8xmB56PTFzupb45ttwQex34eGmYw3gYEA6g@mail.gmail.com>
Subject: Re: [PATCH v6 11/11] arm64: dts: mt7986: add BPI-R3 nand/nor overlays
To:     Frank Wunderlich <linux@fw-web.de>
Cc:     linux-mediatek@lists.infradead.org,
        Frank Wunderlich <frank-w@public-files.de>,
        Ryder Lee <ryder.lee@mediatek.com>,
        Jianjun Wang <jianjun.wang@mediatek.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Bo Jiao <Bo.Jiao@mediatek.com>, linux-pci@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-phy@lists.infradead.org, linux-usb@vger.kernel.org
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On Fri, Nov 18, 2022 at 3:39 PM Rob Herring <robh+dt@kernel.org> wrote:
>
> On Fri, Nov 18, 2022 at 1:01 PM Frank Wunderlich <linux@fw-web.de> wrote:
> >
> > From: Frank Wunderlich <frank-w@public-files.de>
> >
> > Add devicetree overlays for using nand and nor on BPI-R3.
>
> Can you not tell at runtime which one you booted from? If not, how
> does one choose which overlay to apply? If you can, why not populate
> both nodes and enable the right one? IMO, if all h/w is present, it
> should all be in the DT. Selecting what h/w to use is a separate
> problem and overlays aren't a great solution for that.
>
>
> > Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
> > ---
> > maybe rename to dtso?
> >
> > "kbuild: Allow DTB overlays to built from .dtso named source files"
> > https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?h=dt/next&id=363547d2191cbc32ca954ba75d72908712398ff2
> >
> > more comments about the dt overlay-support:
> >
> > https://patchwork.kernel.org/comment/25092116/
> > https://patchwork.kernel.org/comment/25085681/
> > ---
> > v4:
> > - drop compile-comment from overlays
> > - add author-information to dt-overlays
> > ---
> >  arch/arm64/boot/dts/mediatek/Makefile         |  2 +
> >  .../mediatek/mt7986a-bananapi-bpi-r3-nand.dts | 55 +++++++++++++++
> >  .../mediatek/mt7986a-bananapi-bpi-r3-nor.dts  | 69 +++++++++++++++++++
> >  3 files changed, 126 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
>
> These need rules to apply them to the base dtb(s). You just need:
>
> full.dtb := base.dtb overlay.dtb

Oops, that should be:

full-dtbs := base.dtb overlay.dtb
dtb-y += full.dtb

Just like multiple objs in a module.

Rob