linux-kernel - Re: [PATCH v4 1/4] dt-bindings: dmaengine: Add MediaTek Command-Queue DMA controller bindings

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Date:   Fri, 29 May 2020 13:24:43 -0600
From:   Rob Herring <robh@...nel.org>
To:     EastL <EastL.Lee@...iatek.com>
Cc:     Sean Wang <sean.wang@...iatek.com>, vkoul@...nel.org,
        mark.rutland@....com, matthias.bgg@...il.com,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        wsd_upstream@...iatek.com
Subject: Re: [PATCH v4 1/4] dt-bindings: dmaengine: Add MediaTek
 Command-Queue DMA controller bindings

On Thu, May 28, 2020 at 05:57:09PM +0800, EastL wrote:
> Document the devicetree bindings for MediaTek Command-Queue DMA controller
> which could be found on MT6779 SoC or other similar Mediatek SoCs.
> 
> Signed-off-by: EastL <EastL.Lee@...iatek.com>

Need a full name.

> ---
>  .../devicetree/bindings/dma/mtk-cqdma.yaml         | 100 +++++++++++++++++++++
>  1 file changed, 100 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/mtk-cqdma.yaml
> 
> diff --git a/Documentation/devicetree/bindings/dma/mtk-cqdma.yaml b/Documentation/devicetree/bindings/dma/mtk-cqdma.yaml
> new file mode 100644
> index 0000000..045aa0c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/mtk-cqdma.yaml
> @@ -0,0 +1,100 @@
> +# SPDX-License-Identifier: GPL-2.0

Dual license new bindings:

(GPL-2.0-only OR BSD-2-Clause)

> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/dma/mtk-cqdma.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek Command-Queue DMA controller Device Tree Binding
> +
> +maintainers:
> +  - EastL <EastL.Lee@...iatek.com>
> +
> +description:
> +  MediaTek Command-Queue DMA controller (CQDMA) on Mediatek SoC
> +  is dedicated to memory-to-memory transfer through queue based
> +  descriptor management.
> +

Need a $ref to dma-controller.yaml

> +properties:
> +  "#dma-cells":
> +    minimum: 1
> +    # Should be enough
> +    maximum: 255
> +    description:
> +      Used to provide DMA controller specific information.
> +
> +  compatible:
> +    const: mediatek,cqdma

Needs SoC specific compatible string(s).

> +
> +  reg:
> +    minItems: 1
> +    maxItems: 255

You can have 255 register regions?

You need to define what each region is if more than 1.

> +
> +  interrupts:
> +    minItems: 1
> +    maxItems: 255

255 interrupts?

> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    const: cqdma
> +
> +  dma-channel-mask:
> +    description:
> +      Bitmask of available DMA channels in ascending order that are
> +      not reserved by firmware and are available to the
> +      kernel. i.e. first channel corresponds to LSB.
> +      The first item in the array is for channels 0-31, the second is for
> +      channels 32-63, etc.
> +    allOf:
> +      - $ref: /schemas/types.yaml#/definitions/uint32-array
> +    items:
> +      minItems: 1
> +      # Should be enough
> +      maxItems: 255

This already has a definition in dma-common.yaml. Don't copy-n-paste 
it. Just add any constraints you have. Like what is the max number of 
channels?

> +
> +  dma-channels:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +      Number of DMA channels supported by the controller.
> +
> +  dma-requests:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description:
> +      Number of DMA request signals supported by the controller.

Same comment on these 2.

> +
> +required:
> +  - "#dma-cells"
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +  - clock-names
> +  - dma-channel-mask
> +  - dma-channels
> +  - dma-requests
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/clock/mt6779-clk.h>
> +    cqdma: dma-controller@...12000 {
> +        compatible = "mediatek,cqdma";
> +        reg = <0 0x10212000 0 0x80>,
> +            <0 0x10212080 0 0x80>,
> +            <0 0x10212100 0 0x80>;

Examples default to 1 cell each for address and size.

> +        interrupts = <GIC_SPI 139 IRQ_TYPE_LEVEL_LOW>,
> +            <GIC_SPI 140 IRQ_TYPE_LEVEL_LOW>,
> +            <GIC_SPI 141 IRQ_TYPE_LEVEL_LOW>;
> +        clocks = <&infracfg_ao CLK_INFRA_CQ_DMA>;
> +        clock-names = "cqdma";
> +        dma-channel-mask = <63>;
> +        dma-channels = <3>;
> +        dma-requests = <32>;
> +        #dma-cells = <1>;
> +    };
> +
> +...
> -- 
> 1.9.1