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Date:   Tue, 30 Mar 2021 08:58:14 -0500
From:   Rob Herring <robh@kernel.org>
To:     Po-Kai Chi <pk.chi@mediatek.com>
Cc:     Matthias Brugger <matthias.bgg@gmail.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
        wsd_upstream@mediatek.com, CC Hwang <cc.hwang@mediatek.com>,
        Loda Chou <loda.chou@mediatek.com>
Subject: Re: [PATCH v1 1/4] dt-bindings: memory: Add binding for MediaTek
 Common DRAM Controller
Message-ID: <20210330135814.GA224111@robh.at.kernel.org>
References: <1617081731-7408-1-git-send-email-pk.chi@mediatek.com>
 <1617081731-7408-2-git-send-email-pk.chi@mediatek.com>
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On Tue, Mar 30, 2021 at 01:22:08PM +0800, Po-Kai Chi wrote:
> This patch adds the documentation of the device-tree binding for
> MediaTek Common DRAM Controller.
> 
> Signed-off-by: Po-Kai Chi <pk.chi@mediatek.com>
> ---
>  .../memory-controllers/mediatek,dramc.yaml         |  155 ++++++++++++++++++++
>  1 file changed, 155 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/mediatek,dramc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/mediatek,dramc.yaml b/Documentation/devicetree/bindings/memory-controllers/mediatek,dramc.yaml
> new file mode 100644
> index 0000000..0217ce0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/mediatek,dramc.yaml
> @@ -0,0 +1,155 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (c) 2021 MediaTek Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/memory-controllers/mediatek,dramc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek DRAM Controller
> +
> +maintainers:
> +  - Po-Kai Chi <pk.chi@mediatek.com>
> +
> +description: |
> +  MediaTek DRAM controller (DRAMC) provides an interface to query information
> +  about DRAM which collected from bootloader and device tree.
> +  This is mainly used by MediaTek Extended Memory Interface (EMI) and DVFS Resource
> +  Control (DVFSRC).
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - mediatek,mt6779-dramc
> +
> +  reg:
> +    description:
> +      Base address of MediaTek DRAM related hardware modules, each channel has
> +      its own base address in order of
> +      DRAMC_AO_{CH}, DRAMC_NAO_{CH}, DDRPHY_AO_{CH}.
> +    minItems: 3            # 3 * N channels
> +    maxItems: 6
> +
> +  dram_type:

These need to be either common or have a vendor prefix.

Also, s/_/-/

> +    description:
> +      The DRAM type of current DRAM chip.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 7
> +
> +  support_channel_cnt:
> +    description:
> +      The maximum DRAM channel count supported by SoC.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 1
> +    maximum: 4
> +
> +  channel_cnt:
> +    description:
> +      The DRAM channel count of current DRAM chip.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 1
> +    maximum: 4
> +
> +  rank_cnt:
> +    description:
> +      The DRAM rank count of current DRAM chip.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 1
> +    maximum: 2
> +
> +  rank_size:
> +    description:
> +      The size of each DRAM rank.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint64
> +    minItems: 1
> +    maxItems: 2
> +    items:
> +      minimum: 0x0
> +      maximum: 0x100000000    # support up to 4GB in single rank
> +
> +  mr_cnt:
> +    description:
> +      Specifies how many sets of DRAM mode register information to provide.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    maximum: 40    # total 40 MRs for JEDEC LPDDR4X
> +
> +  mr:
> +    description:
> +      Pair of DRAM mode register information.
> +      This property is filled in by bootloader according to the board hardware
> +      configuration.
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +    maxItems: 40    # align with mr_cnt
> +    items:
> +      items:
> +        - description:
> +            Mode register index
> +        - description:
> +            Mode register value
> +
> +  freq_cnt:
> +    description:
> +      Specifies how many sets of DRAM data clock rate supported by SoC.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  freq_step:
> +    description:
> +      The DRAM data clock rate may be slightly different from those defined
> +      by the specification due to errors in multiples of the base frequency.
> +      This describe the mapping from real data clock rate measured by
> +      frequency meter to JEDEC data clock rate.
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +    items:
> +      items:
> +        - description:
> +            Real data rate
> +        - description:
> +            Spec data rate

Looks like an OPP table.

> +
> +required:
> +  - compatible
> +  - reg
> +  - dram_type
> +  - support_channel_cnt
> +  - channel_cnt
> +  - rank_cnt
> +  - mr_cnt
> +  - freq_cnt
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    dramc@10230000 {
> +        compatible = "mediatek,mt6779-dramc";
> +        reg = <0 0x10230000 0 0x2000>, /* DRAMC AO CHA */
> +            <0 0x10240000 0 0x2000>,   /* DRAMC AO CHB */
> +            <0 0x10234000 0 0x1000>,   /* DRAMC NAO CHA */
> +            <0 0x10244000 0 0x1000>,   /* DRAMC NAO CHB */
> +            <0 0x10238000 0 0x2000>,   /* DDRPHY AO CHA */
> +            <0 0x10248000 0 0x2000>;   /* DDRPHY AO CHB */
> +        dram_type = <0>;
> +        support_channel_cnt = <2>;
> +        channel_cnt = <2>;
> +        rank_cnt = <2>;
> +        rank_size = <0x40000000 0x40000000>;

You defined this as 64-bit, so this is a single value?

> +        mr_cnt = <1>;
> +        mr = <0x5 0xff>;
> +        freq_cnt = <6>;
> +        freq_step = <3718 3733>,
> +                <3094 3200>,
> +                <2392 2400>,
> +                <1534 1600>,
> +                <1196 1200>,
> +                <754 800>;
> +    };
> -- 
> 1.7.9.5
>