Re: [PATCH] arm64: dts: rockchip: Assign a fixed index to mmc devices on rk3399-roc-pc boards.

[Robin Murphy]

On 2020-11-04 11:15, Markus Reichl wrote:
> Hi Heiko,
>
> Am 04.11.20 um 11:51 schrieb Heiko Stübner:
> > 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@xxxxxxxxxxxxx>
> > > ---
> > >  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/arm64/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 = "Firefly ROC-RK3399-PC Board";
> > >      compatible = "firefly,roc-rk3399-pc", "rockchip,rk3399";
> > >
> > > +    aliases {
> > > +        mmc0 = &sdmmc;
> > > +        mmc1 = &sdhci;
> > > +    };
> > > +
> >
> > Any reason for this odering?
>
> Without pinning roc-pc mostly booted as
> mmcblk0 = sdmmc = µSD
> mmcblk1 = sdhci = eMMC
> so I kept this behaviour in aliases
>
> roc-pc-mezzanine with populated SDIO-M2-slot booted
> mmc0 = sdio = (no mmcblk)
> mmcblk1 = sdmmc = µSD
> mmcblk2 = sdhci = eMMC

FWIW that's also how my NanoPC-T4 behaves. Given that it's the order 
they appear in the DT, not too surprising ;)

Robin.

> With my aliases both boards behave the same now and the optional SDIO slot
> goes out of the way to mmc2.
>
> > 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, 
> > sdio.
>
> The boards from my zoo (exynos, rk3399) mostly come up with SD-card as mmc0
> and eMMC as mmc1 in mainline as opposed in some vendor kernels.
> but I have no objection to set it the other way round if this is more 
> common
> with rk3399 boards.
>
> > And I guess a further question would be when we're doing arbitary 
> > orderings
> > anyway, why is this not in rk3399.dtsi ;-) ?
>
> I restricted the ordering to the boards I have, not to confuse other 
> established
> use cases, but if a standard ordering is desired this can go to 
> rk3399.dtsi.
>
> > Heiko
>
> Gruß,