RE: [PATCH 1/4] dt-bindings: mmc: renesas_sdhi: Add r8a77470 support

[Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>]

Hello Geert,

> Subject: Re: [PATCH 1/4] dt-bindings: mmc: renesas_sdhi: Add r8a77470 support
>
> Hi Fabrizio,
>
> On Fri, Sep 21, 2018 at 1:55 PM Fabrizio Castro
> <fabrizio.castro@xxxxxxxxxxxxxx> wrote:
> > Document SDHI support for the RZ/G1C (a.k.a. R8A77470) SoC.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> > Reviewed-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/mmc/tmio_mmc.txt | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mmc/tmio_mmc.txt b/Documentation/devicetree/bindings/mmc/tmio_mmc.txt
> > index c434200..8f3a113 100644
> > --- a/Documentation/devicetree/bindings/mmc/tmio_mmc.txt
> > +++ b/Documentation/devicetree/bindings/mmc/tmio_mmc.txt
> > @@ -17,6 +17,7 @@ Required properties:
> >                 "renesas,sdhi-r8a7740" - SDHI IP on R8A7740 SoC
> >                 "renesas,sdhi-r8a7743" - SDHI IP on R8A7743 SoC
> >                 "renesas,sdhi-r8a7745" - SDHI IP on R8A7745 SoC
> > +               "renesas,sdhi-r8a77470" - SDHI IP on R8A77470 SoC
> >                 "renesas,sdhi-r8a7778" - SDHI IP on R8A7778 SoC
> >                 "renesas,sdhi-r8a7779" - SDHI IP on R8A7779 SoC
> >                 "renesas,sdhi-r8a7790" - SDHI IP on R8A7790 SoC
>
> It seems RZ/G1C has two slighty different types of SD card interfaces:
>   1. SDHI0 and SDHI2 use SYS-DMAC,
>   2. SDHI1 can also be used as an MMC interface, and has an internal DMAC.
>
> Do we need to distinguish between them using the compatible value, or
> are there other ways?

The most sensible thing to do here is probably to distinguish between them using
the compatible value, we were thinking about using the following for SDHI1:
compatible = "renesas,sdhi-mmc-r8a77470", "renesas,rcar-gen3-sdhi";

What do you guys think?

I have a prototype for this and it seems to be working fine, but I have only run some
basic checks at run time on the MMC, that's why I haven't sent anything just yet.

Thanks,
Fab

>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds



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