linux-kernel - Re: [PATCH] dt-bindings: mmc: renesas,sdhi: Document RZ/T2H and RZ/N2H support

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Message-ID: <CAMuHMdUBVuHf91r_O6w9Ez0ixF_DE+h8_xHYSkiGeNyBPCkTyg@mail.gmail.com>
Date: Fri, 13 Jun 2025 17:56:40 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	linux-mmc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH] dt-bindings: mmc: renesas,sdhi: Document RZ/T2H and
 RZ/N2H support

Hi Prabhakar,

On Fri, 13 Jun 2025 at 17:38, Lad, Prabhakar <prabhakar.csengg@...il.com> wrote:
>
> Hi Geert,
>
> Thank you for the review.
>
> On Thu, Jun 12, 2025 at 4:47 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> >
> > Hi Prabhakar,
> >
> > On Tue, 10 Jun 2025 at 01:23, Prabhakar <prabhakar.csengg@...il.com> wrote:
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > >
> > > Add SDHI bindings for the Renesas RZ/T2H (a.k.a R9A09G077) and RZ/N2H
> > > (a.k.a R9A09G087) SoCs. Use `renesas,sdhi-r9a09g057` as a fallback since
> > > the SD/MMC block on these SoCs is identical to the one on RZ/V2H(P),
> > > allowing reuse of the existing driver without modifications.
> > >
> > > Update the binding schema to reflect differences: unlike RZ/V2H(P),
> > > RZ/T2H and RZ/N2H do not require the `resets` property and use only a
> > > single clock instead of four.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > > +++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > > @@ -129,59 +131,75 @@ allOf:
> > >          compatible:
> > >            contains:
> > >              enum:
> > > -              - renesas,sdhi-r9a09g057
> > > -              - renesas,rzg2l-sdhi
> > > +              - renesas,sdhi-r9a09g077
> > > +              - renesas,sdhi-r9a09g087
> > >      then:
> > >        properties:
> > > +        resets: false
> > >          clocks:
> > > -          items:
> > > -            - description: IMCLK, SDHI channel main clock1.
> > > -            - description: CLK_HS, SDHI channel High speed clock which operates
> > > -                           4 times that of SDHI channel main clock1.
> > > -            - description: IMCLK2, SDHI channel main clock2. When this clock is
> > > -                           turned off, external SD card detection cannot be
> > > -                           detected.
> > > -            - description: ACLK, SDHI channel bus clock.
> > > +          description: ACLK, SDHI channel bus clock.
> >
> > According to the documentation, this is the SDHI high speed clock...
> >
> Agreed, I will update it to `CLKHS, SDHI channel High speed clock.`
>
> > > +          maxItems: 1
> > >          clock-names:
> > > -          items:
> > > -            - const: core
> > > -            - const: clkh
> > > -            - const: cd
> > > -            - const: aclk
> > > -      required:
> > > -        - clock-names
> > > -        - resets
> > > +          const: aclk
> >
> > ... i.e. clkhs.
> s/clkhs/clkh

The documentation calls it "clkhs".
In addition, calling it "clkh" may confuse the driver if it turns out to be
identical to the main (first, unnamed) clock:

    priv->clk = devm_clk_get(&pdev->dev, NULL);
    if (IS_ERR(priv->clk))
            return dev_err_probe(&pdev->dev, PTR_ERR(priv->clk),
"cannot get clock");

    priv->clkh = devm_clk_get_optional(&pdev->dev, "clkh");
    if (IS_ERR(priv->clkh))
            return dev_err_probe(&pdev->dev, PTR_ERR(priv->clkh),
"cannot get clkh");

    ...

    if (priv->clkh) {
            /* HS400 with 4TAP needs different clock settings */
            ...
    }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

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