Re: [PATCH] ARM: dts: exynos: Assign a fixed index to mmc devices on exynos4412 based ODROID boards

[Robin Murphy]

On 2020-11-05 08:31, Markus Reichl wrote:
> Hi Marek,
>
> on rk3399 the proposed ordering [1] is according to base address in DT.

FWIW, note that in RK3399's case the SoC itself provides no logical 
numbering to follow - the pin groups are named "EMMC", "SDIO0" and 
"SDMMC0" in the datasheet, while the TRM uses "emmc", "sdio" and "sdmmc" 
in signal and register names.

If the SoC *does* have an inherent notion of numbered interfaces, I 
would agree that following that numbering is the most logical thing to do.

Robin.

> [1]
> https://patchwork.kernel.org/patch/11881427
>
> Am 04.11.20 um 14:44 schrieb Marek Szyprowski:
> > On 04.11.2020 14:13, Marek Szyprowski wrote:
> > > On 04.11.2020 14:06, Markus Reichl wrote:
> > > > Am 04.11.20 um 13:25 schrieb Marek Szyprowski:
> > > > > On 04.11.2020 11:25, Markus Reichl wrote:
> > > > > > Recently introduced async probe on mmc devices can shuffle block IDs.
> > > > > > Pin them to fixed values to ease booting in evironments where UUIDs
> > > > > > ar 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/arm/boot/dts/exynos4412-odroid-common.dtsi | 5 +++++
> > > > > >    1 file changed, 5 insertions(+)
> > > > > >
> > > > > > diff --git a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > > > > > b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > > > > > index a5c1ce1e396c..aa10d5bc7e1c 100644
> > > > > > --- a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > > > > > +++ b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi
> > > > > > @@ -13,6 +13,11 @@
> > > > > >    #include "exynos-mfc-reserved-memory.dtsi"
> > > > > >      / {
> > > > > > +    aliases {
> > > > > > +        mmc0 = &sdhci_2;
> > > > > > +        mmc1 = &mshc_0;
> > > > > Like in the OdroidXU3-family patch, I would use 0 for the eMMC 
> > > > > (mshc_0)
> > > > > and 2 for the SD-card (sdhci_2).
> > > > How to deal then with sdhci_0 (from exynos4.dtsi) vc. mshc_0 (from
> > > > exynos4412.dts)?
> > > sdhci_0 and mshc_0 both operate on the same physical MMC0 bus, so this
> > > is not an issue. They cannot be used simultaneously. The latter is just
> > > faster, the first one has been left there mainly for the software
> > > compatibility.
> >
> > I've thought a bit more on this and I would simply prefer to add generic
> > MMC aliases to the top-level Exynos dtsi files (3250, 4210, 4412, 5250,
> > 5410, 5420) to keep Linux logical MMC bus numbers in sync with the HW
> > bus numbers on all boards.
> >
> > Best regards
>
> Gruß,
>
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