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Date:   Fri, 9 Jun 2023 10:58:57 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     William Zhang <william.zhang@broadcom.com>
Cc:     Broadcom Kernel List <bcm-kernel-feedback-list@broadcom.com>,
        Linux MTD List <linux-mtd@lists.infradead.org>,
        f.fainelli@gmail.com, rafal@milecki.pl, kursad.oney@broadcom.com,
        joel.peshkin@broadcom.com, computersforpeace@gmail.com,
        anand.gore@broadcom.com, dregan@mail.com, kamal.dasu@broadcom.com,
        tomer.yacoby@broadcom.com, dan.beygelman@broadcom.com,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Richard Weinberger <richard@nod.at>,
        Kamal Dasu <kdasu.kdev@gmail.com>,
        Rob Herring <robh+dt@kernel.org>
Subject: Re: [PATCH 05/12] dt-bindings: mtd: brcmnand: Updates for bcmbca
 SoCs
Message-ID: <20230609105857.7256c02f@xps-13>
In-Reply-To: <84e97108-29d4-5103-14f4-03e3c0eba165@broadcom.com>
References: <20230606231252.94838-1-william.zhang@broadcom.com>
        <20230606231252.94838-6-william.zhang@broadcom.com>
        <20230607101452.4c265d7e@xps-13>
        <84e97108-29d4-5103-14f4-03e3c0eba165@broadcom.com>
Organization: Bootlin
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Hi William,

william.zhang@broadcom.com wrote on Wed, 7 Jun 2023 13:01:56 -0700:

> Hi Miquel,
>=20
> On 06/07/2023 01:14 AM, Miquel Raynal wrote:
> > Hi William,
> >=20
> > william.zhang@broadcom.com wrote on Tue,  6 Jun 2023 16:12:45 -0700:
> >  =20
> >> Use new compatiable brcm,nand-bcmbca to support BCMBCA broadband
> >> product. The old compatible string is still kept in the driver so old
> >> dtb can still work.
> >>
> >> Add brcm,nand-use-wp property to have an option for disabling this
> >> feature on broadband board design that does not use write protection.
> >> Add brcm,nand-ecc-use-strap to get ecc setting from board strap for
> >> broadband board designs because they do not specify ecc setting in dts
> >> but rather using the strap setting.
> >>
> >> Remove the requirement of interrupts and interrupt-names properties to
> >> reflect the driver code.
> >>
> >> This patch also includes a few minor fixes to the BCM63xx compatibles
> >> and add myself to the list of maintainers.
> >>
> >> Signed-off-by: William Zhang <william.zhang@broadcom.com>
> >> ---
> >>
> >>   .../bindings/mtd/brcm,brcmnand.yaml           | 64 +++++++++++++----=
--
> >>   1 file changed, 43 insertions(+), 21 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml =
b/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> >> index 1571024aa119..1fe1c166a9db 100644
> >> --- a/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> >> +++ b/Documentation/devicetree/bindings/mtd/brcm,brcmnand.yaml
> >> @@ -9,6 +9,7 @@ title: Broadcom STB NAND Controller
> >>   maintainers:
> >>     - Brian Norris <computersforpeace@gmail.com>
> >>     - Kamal Dasu <kdasu.kdev@gmail.com>
> >> +  - William Zhang <william.zhang@broadcom.com> =20
> >>   >>   description: | =20
> >>     The Broadcom Set-Top Box NAND controller supports low-level access=
 to raw NAND
> >> @@ -18,9 +19,10 @@ description: |
> >>     supports basic PROGRAM and READ functions, among other features. =
=20
> >>   >>     This controller was originally designed for STB SoCs (BCM7xxx=
) but is now =20
> >> -  available on a variety of Broadcom SoCs, including some BCM3xxx, BC=
M63xx, and
> >> -  iProc/Cygnus. Its history includes several similar (but not fully r=
egister
> >> -  compatible) versions.
> >> +  available on a variety of Broadcom SoCs, including some BCM3xxx, MI=
PS based
> >> +  Broadband SoC (BCM63xx), ARM based Broadband SoC (BCMBCA) and iProc=
/Cygnus.
> >> +  Its history includes several similar (but not fully register compat=
ible)
> >> +  versions. =20
> >>   >>     -- Additional SoC-specific NAND controller properties --
> >>   >> @@ -53,9 +55,9 @@ properties: =20
> >>                 - brcm,brcmnand-v7.2
> >>                 - brcm,brcmnand-v7.3
> >>             - const: brcm,brcmnand
> >> -      - description: BCM63138 SoC-specific NAND controller
> >> +      - description: BCMBCA SoC-specific NAND controller
> >>           items:
> >> -          - const: brcm,nand-bcm63138
> >> +          - const: brcm,nand-bcmbca
> >>             - enum:
> >>                 - brcm,brcmnand-v7.0
> >>                 - brcm,brcmnand-v7.1
> >> @@ -65,11 +67,15 @@ properties:
> >>             - const: brcm,nand-iproc
> >>             - const: brcm,brcmnand-v6.1
> >>             - const: brcm,brcmnand
> >> -      - description: BCM63168 SoC-specific NAND controller
> >> +      - description: BCM63xx SoC-specific NAND controller
> >>           items:
> >> -          - const: brcm,nand-bcm63168
> >> -          - const: brcm,nand-bcm6368
> >> -          - const: brcm,brcmnand-v4.0
> >> +          - enum:
> >> +              - brcm,nand-bcm63168
> >> +              - brcm,nand-bcm6368
> >> +          - enum:
> >> +              - brcm,brcmnand-v2.1
> >> +              - brcm,brcmnand-v2.2
> >> +              - brcm,brcmnand-v4.0
> >>             - const: brcm,brcmnand =20
> >>   >>     reg: =20
> >> @@ -111,6 +117,19 @@ properties:
> >>         earlier versions of this core that include WP
> >>       type: boolean =20
> >>   >> +  brcm,nand-use-wp: =20
> >> +    description:
> >> +      Use this integer to indicate if board design uses
> >> +      controller's write protection feature and connects its
> >> +      NAND_WPb pin to nand chip's WP_L pin. Driver defaults to
> >> +      use this feature when this property does not exist.
> >> +      Set to 0 if WP pins are not connected and feature is not
> >> +      used. Set to 1 if WP pins are connected and feature is used.
> >> +      Set to 2 if WP pins are connected but disable this feature
> >> +      through driver that sets controller to output high on NAND_WPb.
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    enum: [0, 1, 2] =20
> >=20
> > Perhaps strings would be welcome. I'll let binding maintainers say what
> > they think of it.
> >  =20
> Practically there is really just use cases of 0 and 1. I could use a bool=
 flag but to keep consistent with the driver code and in case there is any =
existing usage of 2.
>=20
> >> +
> >>   patternProperties:
> >>     "^nand@[a-f0-9]$":
> >>       type: object
> >> @@ -136,13 +155,23 @@ patternProperties:
> >>             layout.
> >>           $ref: /schemas/types.yaml#/definitions/uint32 =20
> >>   >> +      brcm,nand-ecc-use-strap: =20
> >> +        description:
> >> +          This flag is used by the driver to get the ecc strength and
> >> +          spare area size from the SoC NAND boot strap setting. This
> >> +          is commonly used by the BCMBCA SoC board design. If ecc
> >> +          strength and spare area size are set by nand-ecc-strength
> >> +          and brcm,nand-oob-sector-size in the dts, these settings
> >> +          have precedence and override this flag.
> >> +        $ref: /schemas/types.yaml#/definitions/flag =20
> >=20
> > How in practice do you access the strap value? Don't you need a phandle
> > over a specific area in the SoC?
> >  =20
> The strap value is latched and stored in the NAND controller register so =
there is no extra phandle needed.

Ok.

>=20
> >> +
> >>   allOf:
> >>     - $ref: nand-controller.yaml#
> >>     - if:
> >>         properties:
> >>           compatible:
> >>             contains:
> >> -            const: brcm,nand-bcm63138
> >> +            const: brcm,nand-bcmbca
> >>       then:
> >>         properties:
> >>           reg-names:
> >> @@ -153,7 +182,9 @@ allOf:
> >>         properties:
> >>           compatible:
> >>             contains:
> >> -            const: brcm,nand-bcm6368
> >> +            enum:
> >> +              - brcm,nand-bcm63168
> >> +              - brcm,nand-bcm6368
> >>       then:
> >>         properties:
> >>           reg-names:
> >> @@ -173,20 +204,12 @@ allOf:
> >>               - const: nand
> >>               - const: iproc-idm
> >>               - const: iproc-ext
> >> -  - if:
> >> -      properties:
> >> -        interrupts:
> >> -          minItems: 2
> >> -    then:
> >> -      required:
> >> -        - interrupt-names =20
> >=20
> > Why do you remove this? Removing "interrupts" from the required
> > properties is fine, but constraining the interrupts property when it is
> > relevant is still expected.
> >  =20
> There is no requirement for interrupt name even if it have two interrupts=
. Driver code does not use interrupt name but the interrupt index instead.

It does not matter in this case how the driver uses the interrupts. If
names have been provided once in the bindings, you could expect another
project using the same bindings to use the interrupt names instead of
the order. So you must keep the names. Just don't mark them required it
they are.

>=20
> >>   >>   unevaluatedProperties: false
> >>   >>   required: =20
> >>     - reg
> >>     - reg-names
> >> -  - interrupts =20
> >=20
> > This should be done in a separate patch.
> >  =20
> I thought this is also related to my update for bcmbca chips because they=
 don't need to interrupt and interrupt name.

The fact that the driver does not use the interrupts does not mean they
should not be described.=20

>=20
> >>   >>   examples: =20
> >>     - |
> >> @@ -215,8 +238,7 @@ examples:
> >>       };
> >>     - |
> >>       nand-controller@10000200 {
> >> -        compatible =3D "brcm,nand-bcm63168", "brcm,nand-bcm6368",
> >> -                     "brcm,brcmnand-v4.0", "brcm,brcmnand";
> >> +        compatible =3D "brcm,nand-bcm6368", "brcm,brcmnand-v2.1", "br=
cm,brcmnand";
> >>           reg =3D <0x10000200 0x180>,
> >>                 <0x100000b0 0x10>,
> >>                 <0x10000600 0x200>; =20
> >=20
> >=20
> > Thanks,
> > Miqu=C3=A8l
> >  =20


Thanks,
Miqu=C3=A8l