RE: [PATCH 4/4] ARM: dts: iwg23s-sbc: Add uSD card support

[Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>]

Hello Geert,

Thank you for your feedback.

> Subject: Re: [PATCH 4/4] ARM: dts: iwg23s-sbc: Add uSD card support
>
> Hi Fabrizio,
>
> On Mon, Sep 24, 2018 at 11:30 AM Fabrizio Castro
> <fabrizio.castro@xxxxxxxxxxxxxx> wrote:
> > > -----Original Message-----
> > > From: Simon Horman <horms@xxxxxxxxxxxx>
> > > Sent: 24 September 2018 10:14
> > > To: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> > > Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; Laurent
> > > Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>; Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Linus Walleij
> > > <linus.walleij@xxxxxxxxxx>; Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>; Magnus Damm <magnus.damm@xxxxxxxxx>;
> > > linux-mmc@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-renesas-soc@xxxxxxxxxxxxxxx; linux-gpio@xxxxxxxxxxxxxxx; Chris
> > > Paterson <Chris.Paterson2@xxxxxxxxxxx>; Biju Das <biju.das@xxxxxxxxxxxxxx>
> > > Subject: Re: [PATCH 4/4] ARM: dts: iwg23s-sbc: Add uSD card support
> > >
> > > On Fri, Sep 21, 2018 at 12:55:11PM +0100, Fabrizio Castro wrote:
> > > > Add uSD card support to the iwg23s single board computer powered
> > > > by the RZ/G1C SoC (a.k.a. r8a77470).
> > > >
> > > > Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
> > > > Reviewed-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > > > ---
> > > > Hello Simon,
> > > >
> > > > this patch can only be taken after patch "pinctrl: sh-pfc: r8a77470:
> > > > Add SDHI2 voltage switch" from this series appears on a release candidate
> > > > or a release.
> > >
> > > What is the nature of that dependency. Does adding this patch without
> > > its dependency cause a regression?
> >
> > Since the SDHI2 pins definition contain "power-source" property, adding this
> > patch without its dependency will cause an error at boot up as the kernel
> > would be looking for flag SH_PFC_PIN_CFG_IO_VOLTAGE for each pin contained
> > in sdhi2_pins and sdhi2_pins_uhs, and since that particular flag would be missing
> > (as such a definition comes from patch "pinctrl: sh-pfc: r8a77470: Add SDHI2 voltage
> > switch") the SD card would not be functional, but this won't have any impact on
> > the rest of the system.
>
> But that won't be a regression, as currently there's no support for
> SDHI2 anyway,
> right? All pieces will start working when both the pinctrl and DTS support will
> be merged together.

Exactly, it won't be a regression, you'd just get weird messages from the kernel, that's all.

Thanks,
Fab

>
> This is different from the case where you first add a device node to enable a
> device (which makes it work), and later add pinctrl properties (which may
> break it, if the pinctrl driver doesn't have support for it yet).
>
> 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



Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.