linux-kernel - Re: [PATCH v3 1/3] dt-bindings: mmc: renesas,sdhi: Document RZ/V2H(P) support

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Date: Tue, 25 Jun 2024 10:07:13 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Magnus Damm <magnus.damm@...il.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 v3 1/3] dt-bindings: mmc: renesas,sdhi: Document RZ/V2H(P) support

Hi Geert,

On Tue, Jun 25, 2024 at 10:02 AM Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Tue, Jun 25, 2024 at 10:47 AM Lad, Prabhakar
> <prabhakar.csengg@...il.com> wrote:
> > On Tue, Jun 25, 2024 at 7:57 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > > On Mon, Jun 24, 2024 at 5:33 PM Prabhakar <prabhakar.csengg@...il.com> wrote:
> > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > >
> > > > The SD/MMC block on the RZ/V2H(P) ("R9A09G057") SoC is similar to that
> > > > of the R-Car Gen3, but it has some differences:
> > > > - HS400 is not supported.
> > > > - It supports the SD_IOVS bit to control the IO voltage level.
> > > > - It supports fixed address mode.
> > > >
> > > > To accommodate these differences, a SoC-specific 'renesas,sdhi-r9a09g057'
> > > > compatible string is added.
> > > >
> > > > A 'vqmmc-regulator' object is introduced to handle the power enable (PWEN)
> > > > and voltage level switching for the SD/MMC.
> > > >
> > > > Additionally, the 'renesas,sdhi-use-internal-regulator' flag is introduced
> > > > to indicate that an internal regulator is used instead of a
> > > > GPIO-controlled regulator. This flag will help configure the internal
> > > > regulator and avoid special handling when GPIO is used for voltage
> > > > regulation instead of the SD_(IOVS/PWEN) pins.
> > > >
> > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > > ---
> > > > v2->v3
> > > > - Renamed vqmmc-r9a09g057-regulator object to vqmmc-regulator
> > > > - Added regulator-compatible property for vqmmc-regulator
> > > > - Added 'renesas,sdhi-use-internal-regulator' property
> > >
> > > Thanks for the update!
> > >
> > > > --- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > > > +++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > > > @@ -204,6 +207,31 @@ allOf:
> > > >          sectioned off to be run by a separate second clock source to allow
> > > >          the main core clock to be turned off to save power.
> > > >
> > > > +  - if:
> > > > +      properties:
> > > > +        compatible:
> > > > +          contains:
> > > > +            const: renesas,sdhi-r9a09g057
> > > > +    then:
> > > > +      properties:
> > > > +        renesas,sdhi-use-internal-regulator:
> > > > +          $ref: /schemas/types.yaml#/definitions/flag
> > > > +          description:
> > > > +            Flag to indicate internal regulator is being used instead of GPIO regulator.
> > >
> > > Do you really need this?
> > For cases where the status is okay for the regulator but still the
> > user has phandle for the GPIO regulator or shall I drop this case?
>
> I think that case can be ignored.
> The regulator subnode would be disabled by default in the .dtsi, right?
>
Yes, agreed.

> > > The status of the regulator subnode already indicates this.
> > You mean to use of_device_is_available() ?
>
> Exactly. I.e. only register the regulator when it is enabled.
>
Okay I'll use of_device_is_available() and drop the
'renesas,sdhi-use-internal-regulator' property.

Cheers,
Prabhakar