Aw: Re: [PATCH] arm64: dts: mediatek: Apply all DT overlays at build time

[Frank Wunderlich]

Hi,

this looks similar to my attempt i did here

https://patchwork.kernel.org/project/linux-mediatek/patch/20240608080530.9436-2-linux@fw-web.de/

But in my case i added full dtb with 2 overlays as there can be 2 devices (1 mmc + 1 spi) at one time.
So usable as dtb for bootloader config without overlays, not only for validation...

regards Frank


> Gesendet: Dienstag, 18. November 2025 um 13:31
> Von: "Rob Herring" <robh at kernel.org>
> An: "AngeloGioacchino Del Regno" <angelogioacchino.delregno at collabora.com>
> CC: "Matthias Brugger" <matthias.bgg at gmail.com>, "Krzysztof Kozlowski" <krzk+dt at kernel.org>, "Conor Dooley" <conor+dt at kernel.org>, linux-kernel at vger.kernel.org, linux-arm-kernel at lists.infradead.org, linux-mediatek at lists.infradead.org, devicetree at vger.kernel.org
> Betreff: Re: [PATCH] arm64: dts: mediatek: Apply all DT overlays at build time
>
> On Tue, Nov 18, 2025 at 3:36 AM AngeloGioacchino Del Regno
> <angelogioacchino.delregno at collabora.com> wrote:
> >
> > Il 17/11/25 22:13, Rob Herring (Arm) ha scritto:
> > > It's a requirement that DT overlays be applied at build time in order to
> > > validate them as overlays are not validated on their own.
> > >
> > > Add targets for all the Mediatek overlays.
> > >
> > > Signed-off-by: Rob Herring (Arm) <robh at kernel.org>
> > > ---
> > > This will soon be a warning[1].
> > >
> > > Note that if it is desired that the combined .dtb is not installed, then
> > > the combined .dtb should be added to 'dtb-' variable instead.
> > >
> >
> > Uhm, sorry, can't we do something such that we don't generate a DTB with a
> > preapplied overlay?
> >
> > Even something like generating those and deleting before build finalization
> > could work, I guess, though that'd be hacky maybe.
> >
> > I don't know if this is the case, but I'm worried that various people have
> > scripts to copy DTBs somewhere (in some partition) or embed those in images,
> > and if they get the preapplied overlay dtbs in the same place, havoc could
> > happen as the bootloaders might be selecting wrong dtbs (as a plus, there is
> > no dtbo that varies machine compatible strings, rightfully).
> 
> If they aren't using dtbs_install for that, then that is their
> problem. When we moved all the arm32 DTs to vendor directories,
> dtbs_install maintained the old structure which seemed sufficient to
> not break folks. The same should apply here.
> 
> Rob
> 
>