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From:   Peng Fan <peng.fan@nxp.com>
To:     Shawn Guo <shawnguo@kernel.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>
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        dl-linux-imx <linux-imx@nxp.com>,
        Anson Huang <anson.huang@nxp.com>,
        Leonard Crestez <leonard.crestez@nxp.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Alice Guo <alice.guo@nxp.com>
Subject: RE: [PATCH] ARM: imx: use of_root to simplify code
Thread-Topic: [PATCH] ARM: imx: use of_root to simplify code
Thread-Index: AQHVvvAOkP5pfM/SI0ufVklMt6+KwqfiDDEAgAAAu+A=
Date:   Thu, 9 Jan 2020 08:20:38 +0000
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+Rob

Hi Shawn,

> Subject: Re: [PATCH] ARM: imx: use of_root to simplify code
>=20
> On Mon, Dec 30, 2019 at 09:03:51AM +0000, Peng Fan wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > start_kernel
> >      |->setup_arch
> >      |       |->unflatten_device_tree->of_root ready
> >      |
> >      |->do_initcalls
> >            |->customize_machine
> >                        |->init_machine
> >                               |->imx_soc_device_init
> >
> > When imx_soc_device_init, of_root is ready, so we could directly use it=
.
>=20
> IMO, of_root is something for OF core code, not really for platform.

From below link, I see powerpc and some driver use of_root directly.
https://elixir.bootlin.com/linux/v5.5-rc5/ident/of_root

of_root is exported as a symbol. Rob, could you please clarify whether
platform code could use of_root directly?

Thanks,
Peng.

>=20
> Shawn
>=20
> >
> > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > ---
> >
> > V1:
> >  Tested on i.MX7D-SDB
> >
> >  arch/arm/mach-imx/cpu.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c index
> > 06f8d64b65af..77319b359070 100644
> > --- a/arch/arm/mach-imx/cpu.c
> > +++ b/arch/arm/mach-imx/cpu.c
> > @@ -88,7 +88,6 @@ struct device * __init imx_soc_device_init(void)
> >  	struct soc_device_attribute *soc_dev_attr;
> >  	const char *ocotp_compat =3D NULL;
> >  	struct soc_device *soc_dev;
> > -	struct device_node *root;
> >  	struct regmap *ocotp =3D NULL;
> >  	const char *soc_id;
> >  	u64 soc_uid =3D 0;
> > @@ -101,9 +100,7 @@ struct device * __init imx_soc_device_init(void)
> >
> >  	soc_dev_attr->family =3D "Freescale i.MX";
> >
> > -	root =3D of_find_node_by_path("/");
> > -	ret =3D of_property_read_string(root, "model", &soc_dev_attr->machine=
);
> > -	of_node_put(root);
> > +	ret =3D of_property_read_string(of_root, "model",
> > +&soc_dev_attr->machine);
> >  	if (ret)
> >  		goto free_soc;
> >
> > --
> > 2.16.4
> >