From: Tim Harvey <tharvey@gateworks.com>
To: Alexander Stein <alexander.stein@ew.tq-group.com>
Cc: Rob Herring <robh+dt@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
NXP Linux Team <linux-imx@nxp.com>,
Device Tree Mailing List <devicetree@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>
Subject: Re: (EXT) Re: [PATCH] arm64: dts: imx8mm-venice-gw73xx-0x: add dt overlays for serial modes
Date: Tue, 11 Jan 2022 09:53:29 -0800 [thread overview]
Message-ID: <CAJ+vNU2PxF=9VwMv4f8N5W5Gs2Ynxdn9jHTSkWH7zd3Fo5hBiw@mail.gmail.com> (raw)
In-Reply-To: <2226437.ElGaqSPkdT@steina-w>
On Mon, Jan 10, 2022 at 11:20 PM Alexander Stein
<alexander.stein@ew.tq-group.com> wrote:
>
> Am Dienstag, 11. Januar 2022, 01:00:21 CET schrieb Tim Harvey:
> > [SNIP]
> > > diff --git a/arch/arm64/boot/dts/freescale/Makefile
> > > b/arch/arm64/boot/dts/freescale/Makefile index a14a6173b765..5ec8d59347b6
> > > 100644
> > > --- a/arch/arm64/boot/dts/freescale/Makefile
> > > +++ b/arch/arm64/boot/dts/freescale/Makefile
> > > @@ -44,6 +44,9 @@ dtb-$(CONFIG_ARCH_MXC) += imx8mm-var-som-symphony.dtb
> > >
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw71xx-0x.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw72xx-0x.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x.dtb
> > >
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs422.dtbo
> > > +dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw73xx-0x-rs485.dtbo
> > >
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7901.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mm-venice-gw7902.dtb
> > > dtb-$(CONFIG_ARCH_MXC) += imx8mn-beacon-kit.dtb
> > >
> > [SNIP]
> > I'm mostly interested to see if my approach to dt fragments here and
> > the naming of the files makes sense to others.
> >
> > This patch causes the kernel to build dtbo files for:
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs232-rts.dtbo
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs422.dtbo
> > arch/arm64/boot/dts/freescale/imx8mm-venice-gw73xx-0x-rs485.dtbo
> >
> > The intention is that these files are used by boot firmware (U-Boot)
> > to adjust the dtb before passing it to the kernel.
>
> Hi Tim,
>
> do these dtbo actually work? I'm wondering because I was trying to useoverlays
> myself and noticed that the had to be compiled with -@ for u-boot to be able
> to apply them. Apparently there are 2 possibilities:
Alexander,
Yes, they work, but I do manually set DTC_FLAGS=-@ when building
kernel dtbs to make them work.
> * Set "DTC_FLAGS_[dtb] := -@" yourself
> See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> commit/?id=e426d63e752bdbe7d5ba2d872319dde9ab844a07
>
> * Use dedicated overlay target
> See https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
> commit/?id=15d16d6dadf6947ac7f9a686c615995c5a426ce2
>
> You use neither of them. IIRC just naming the target file .dtbo will not apply
> symbols (-Q) during dtc call. Can you verify using 'V=1'
> Also I'm wondering which way is the best to go.
>
I wasn't aware there was a way to do this via Makefiles. It seems that
perhaps Rob's approach with 'kbuild: Add generic rule to apply
fdtoverlay' is a way to avoid having to add them all manually in the
first approach? I must admit I'm not sure how to use that.
Best regards,
Tim
next prev parent reply other threads:[~2022-01-11 17:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-14 21:36 [PATCH] arm64: dts: imx8mm-venice-gw73xx-0x: add dt overlays for serial modes Tim Harvey
2022-01-11 0:00 ` Tim Harvey
2022-01-11 7:20 ` (EXT) " Alexander Stein
2022-01-11 17:53 ` Tim Harvey [this message]
2022-01-12 6:58 ` (EXT) " Alexander Stein
2022-01-26 7:44 ` Shawn Guo
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