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References: <20201104094950.2096-1-m.reichl@fivetechno.de> <4984701.vSXMUKeAfh@diego>
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From:   Doug Anderson <dianders@chromium.org>
Date:   Wed, 4 Nov 2020 07:42:01 -0800
Message-ID: <CAD=FV=V2Vv0bv-exiZ6VrOtfMM5TVpjATO04qaXeGWDRu+6vyw@mail.gmail.com>
Subject: Re: [PATCH] arm64: dts: rockchip: Assign a fixed index to mmc devices
 on rk3399-roc-pc boards.
To:     =?UTF-8?Q?Heiko_St=C3=BCbner?= <heiko@sntech.de>
Cc:     "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Markus Reichl <m.reichl@fivetechno.de>,
        Rob Herring <robh@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
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Hi,

On Wed, Nov 4, 2020 at 2:51 AM Heiko St=C3=BCbner <heiko@sntech.de> wrote:
>
> Hi Markus,
>
> Am Mittwoch, 4. November 2020, 10:49:45 CET schrieb Markus Reichl:
> > Recently introduced async probe on mmc devices can shuffle block IDs.
> > Pin them to fixed values to ease booting in evironments where UUIDs
> > are not practical. Use newly introduced aliases for mmcblk devices from=
 [1].
> >
> > [1]
> > https://patchwork.kernel.org/patch/11747669/
> >
> > Signed-off-by: Markus Reichl <m.reichl@fivetechno.de>
> > ---
> >  arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi b/arch/arm=
64/boot/dts/rockchip/rk3399-roc-pc.dtsi
> > index e7a459fa4322..bc9482b59428 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi
> > +++ b/arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi
> > @@ -13,6 +13,11 @@ / {
> >       model =3D "Firefly ROC-RK3399-PC Board";
> >       compatible =3D "firefly,roc-rk3399-pc", "rockchip,rk3399";
> >
> > +     aliases {
> > +             mmc0 =3D &sdmmc;
> > +             mmc1 =3D &sdhci;
> > +     };
> > +
>
> Any reason for this odering?
>
> I.e. some previous incarnations had it ordered as (emmc, mmc, sdio).
> This is also true for the ChromeOS out-of-tree usage of those, the
> rk3399 dts in the chromeos-4.4 tree also orders this as sdhci, sdmmc, sdi=
o.
>
> And I guess a further question would be when we're doing arbitary orderin=
gs
> anyway, why is this not in rk3399.dtsi ;-) ?

Though I personally like the idea of eMMC, which is typically
built-in, as being the "0" number, I'm personally happy with any
numbering scheme that's consistent.  Ordering them by base address is
OK w/ me and seems less controversial.  That seems like it could go in
rk3399.dtsi and then if a particular board wanted a different order
they could override it in their board file.  The downside of putting
in rk3399 is that boards that don't have all SD/MMC interfaces enabled
would definitely get a new number compared to old kernels, but
hopefully this is the last time?

-Doug