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 10:19:02 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, 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" <linux-mmc@...r.kernel.org>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v3 1/3] dt-bindings: mmc: renesas,sdhi: Document RZ/V2H(P) support

Hi Biju,

On Tue, Jun 25, 2024 at 10:12 AM Biju Das <biju.das.jz@...renesas.com> wrote:
>
> Hi Prabhakar,
>
> > -----Original Message-----
> > From: Prabhakar <prabhakar.csengg@...il.com>
> > Sent: Monday, June 24, 2024 4:32 PM
> > Subject: [PATCH v3 1/3] dt-bindings: mmc: renesas,sdhi: Document RZ/V2H(P) support
> >
> > 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
> >
> > v1->v2
> > - Moved vqmmc object in the if block
> > - Updated commit message
> > ---
> >  .../devicetree/bindings/mmc/renesas,sdhi.yaml | 30 ++++++++++++++++++-
> >  1 file changed, 29 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > index 3d0e61e59856..20769434a422 100644
> > --- a/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > +++ b/Documentation/devicetree/bindings/mmc/renesas,sdhi.yaml
> > @@ -18,6 +18,7 @@ properties:
> >            - renesas,sdhi-r7s9210 # SH-Mobile AG5
> >            - renesas,sdhi-r8a73a4 # R-Mobile APE6
> >            - renesas,sdhi-r8a7740 # R-Mobile A1
> > +          - renesas,sdhi-r9a09g057 # RZ/V2H(P)
> >            - renesas,sdhi-sh73a0  # R-Mobile APE6
> >        - items:
> >            - enum:
> > @@ -118,7 +119,9 @@ allOf:
> >        properties:
> >          compatible:
> >            contains:
> > -            const: renesas,rzg2l-sdhi
> > +            enum:
> > +              - renesas,sdhi-r9a09g057
> > +              - renesas,rzg2l-sdhi
> >      then:
> >        properties:
> >          clocks:
> > @@ -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.
> > +
> > +        vqmmc-regulator:
> > +          type: object
> > +          description: VQMMC SD regulator
> > +          $ref: /schemas/regulator/regulator.yaml#
> > +          unevaluatedProperties: false
> > +
> > +          properties:
> > +            regulator-compatible:
> > +              pattern: "^vqmmc-r9a09g057-regulator"
> > +
> > +      required:
> > +        - vqmmc-regulator
>
> Maybe we can drop required to make it optional, so that one has the
> option to select between { vqmmc-regulator, gpio regulator}??
>
I think making the regulator node optional isn't correct here as this
internal regulator is always present in the SoC and this has to be
described in the DT no matter if it's being used or not.

Users can always switch between internal regulator and GPIO regulator.
I have provided an example here [0] for both the cases.

[0] https://patchwork.kernel.org/project/linux-renesas-soc/cover/20240624153229.68882-1-prabhakar.mahadev-lad.rj@bp.renesas.com/

Cheers,
Prabhakar