Re: [PATCH 3/3] dt-bindings: mtd: atmel-nand: add deprecated bindings

[Conor Dooley <conor@kernel.org>]

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On Wed, Mar 20, 2024 at 11:22:09AM +0530, Balamanikandan Gunasundar wrote:
> Add nand bindings for legacy nand controllers. These bindings are not used
> with the new device trees. This is still maintained to support legacy dt
> bindings.
> 
> Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@microchip.com>
> ---
>  .../bindings/mtd/atmel-nand-deprecated.yaml        | 156 +++++++++++++++++++++
>  .../devicetree/bindings/mtd/atmel-nand.txt         | 116 ---------------
>  2 files changed, 156 insertions(+), 116 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand-deprecated.yaml b/Documentation/devicetree/bindings/mtd/atmel-nand-deprecated.yaml
> new file mode 100644
> index 000000000000..c8922ab0f1d5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/atmel-nand-deprecated.yaml

Node name matching the devices please.

> @@ -0,0 +1,156 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mtd/atmel-nand-deprecated.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Atmel NAND flash controller deprecated bindings

/stuff/linux-dt/Documentation/devicetree/bindings/mtd/atmel-nand-deprecated.yaml: title: 'Atmel NAND flash controller deprecated bindings' should not be valid under {'pattern': '([Bb]inding| [Ss]chema)'}
	hint: Everything is a binding/schema, no need to say it. Describe what hardware the binding is for.

> +
> +maintainers:
> +  - Balamanikandan Gunasundar <balamanikandan.gunasundar@microchip.com>
> +
> +description: |
> +  This should not be used in the new device trees.

If these should not be used in new files, where are the replacement
bindings for the three devices listed here? I think, rather than being
deprecated, these are the only bindings for these devices and what you
actually want to say here is that these should not be used for /new
devices/. I'd drop mention of deprecation from the title as these
bindings are the only ones for this hardware AFAICT and just say that
new devices should be documented in $new_file.

> +properties:
> +  compatible:
> +    enum:
> +      - atmel,at91rm9200-nand
> +      - atmel,sama5d2-nand
> +      - atmel,sama5d4-nand
> +
> +  reg:

Missing constraints.

> +    description:
> +      should specify localbus address and size used for the chip, and
> +      hardware ECC controller if available. If the hardware ECC is PMECC,
> +      it should contain address and size for PMECC and PMECC Error Location
> +      controller.  The PMECC lookup table address and size in ROM is
> +      optional. If not specified, driver will build it in runtime.
> +
> +  atmel,nand-addr-offset:
> +    description:
> +      offset for the address latch.
> +    $ref: /schemas/types.yaml#/definitions/uint32

Missing constraints.

> +
> +  atmel,nand-cmd-offset:
> +    description:
> +      offset for the command latch.
> +    $ref: /schemas/types.yaml#/definitions/uint32

Missing contraints.

> +
> +  "#address-cells":
> +    description:
> +      Must be present if the device has sub-nodes representing partitions

Does this binding even allow partition child nodes? Hint: it doesn't.

> +  "#size-cells":
> +    description:
> +      Must be present if the device has sub-nodes representing partitions.
> +
> +  gpios:
> +    description:
> +      specifies the gpio pins to control the NAND device. detect is an
> +      optional gpio and may be set to 0 if not present.

Missing constraints (and maybe a type too? I dunno if "gpios" has a
special case in the -gpios regexes).

> +  atmel,nand-has-dma:
> +    description:
> +      support dma transfer for nand read/write.
> +    $ref: /schemas/types.yaml#/definitions/flag
> +
> +  atmel,has-pmecc:
> +    description:
> +      enable Programmable Multibit ECC hardware, capable of BCH encoding
> +      and decoding, on devices where it is present.
> +    $ref: /schemas/types.yaml#/definitions/flag
> +
> +  nand-on-flash-bbt:
> +    description:
> +      enable on flash bbt option if not present false
> +    $ref: /schemas/types.yaml#/definitions/flag
> +
> +  nand-ecc-mode:

Missing a default since this is optional.

> +    description:
> +      operation mode of the NAND ecc mode, soft by default.  Supported
> +    enum:
> +      [none, soft, hw, hw_syndrome, hw_oob_first, soft_bch]
> +    $ref: /schemas/types.yaml#/definitions/string
> +
> +  atmel,pmecc-cap:
> +    description:
> +      error correct capability for Programmable Multibit ECC Controller. If
> +      the compatible string is "atmel,sama5d2-nand", 32 is also valid.
> +    enum:
> +      [2, 4, 8, 12, 24]

You're missing an extra permitted value for the sama5d2.

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  atmel,pmecc-sector-size:

Missing a default since this is optional.

> +    description:
> +      sector size for ECC computation.
> +    enum:
> +      [512, 1024]
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  atmel,pmecc-lookup-table-offset:

Missing a default since this is optional.

> +    description:
> +      includes two offsets of lookup table in ROM for different sector
> +      size. First one is for sector size 512, the next is for sector size
> +      1024. If not specified, driver will build the table in runtime.
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +
> +  nand-bus-width:
> +    description:
> +      nand bus width
> +    enum:
> +      [8, 16]

Missing a default of 8 here.

> +    $ref: /schemas/types.yaml#/definitions/uint32
> +

You're missing the optional child node for the "nand flash controller" on
sama5d2.

> +required:
> +  - compatible
> +  - reg
> +  - atmel,nand-addr-offset
> +  - atmel,nand-cmd-offset
> +  - "#address-cells"
> +  - "#size-cells"
> +  - gpios
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    nand0: nand@40000000,0 {

Drop the unused node name.

> +            compatible = "atmel,at91rm9200-nand";
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            reg = <0x40000000 0x10000000
> +                   0xffffe800 0x200>;
> +            atmel,nand-addr-offset = <21>;	/* ale */
> +            atmel,nand-cmd-offset = <22>;	/* cle */
> +            nand-on-flash-bbt;
> +            nand-ecc-mode = "soft";
> +            gpios = <&pioC 13 0	/* rdy */
> +                     &pioC 14 0 /* nce */
> +                     0		/* cd */
> +                    >;

Please follow the coding style rather than copy-paste from the text
based binding. Applies to both examples. An example with the nfc would
be more helpful than two bindings for the same device.


Thanks,
Conor.

> +    };
> +  - |
> +    /* for PMECC supported chips */
> +    nand1@40000000 {
> +            compatible = "atmel,at91rm9200-nand";
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            reg = <0x40000000 0x10000000	/* bus addr & size */
> +                   0xffffe000 0x00000600	/* PMECC addr & size */
> +                   0xffffe600 0x00000200	/* PMECC ERRLOC addr & size */
> +                   0x00100000 0x00100000>;	/* ROM addr & size */
> +
> +            atmel,nand-addr-offset = <21>;	/* ale */
> +            atmel,nand-cmd-offset = <22>;	/* cle */
> +            nand-on-flash-bbt;
> +            nand-ecc-mode = "hw";
> +            atmel,has-pmecc;	/* enable PMECC */
> +            atmel,pmecc-cap = <2>;
> +            atmel,pmecc-sector-size = <512>;
> +            atmel,pmecc-lookup-table-offset = <0x8000 0x10000>;
> +            gpios = <&pioD 5 0	/* rdy */
> +                     &pioD 4 0	/* nce */
> +                     0		/* cd */
> +                    >;
> +    };

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