linux-kernel - Re: [PATCH] dt-bindings: dma: Convert mtk-uart-apdma to DT schema

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Message-ID: <dc523c4f-e625-7651-2621-fe1aab574a5f@collabora.com>
Date:   Wed, 16 Feb 2022 14:30:22 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        vkoul@...nel.org
Cc:     robh+dt@...nel.org, sean.wang@...iatek.com, matthias.bgg@...il.com,
        long.cheng@...iatek.com, dmaengine@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] dt-bindings: dma: Convert mtk-uart-apdma to DT schema

Il 16/02/22 14:26, Krzysztof Kozlowski ha scritto:
> On 16/02/2022 12:40, AngeloGioacchino Del Regno wrote:
>> Convert the MediaTek UART APDMA Controller binding to DT schema.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>> ---
>>   .../bindings/dma/mediatek,uart-dma.yaml       | 112 ++++++++++++++++++
>>   .../bindings/dma/mtk-uart-apdma.txt           |  56 ---------
>>   2 files changed, 112 insertions(+), 56 deletions(-)
>>   create mode 100644 Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
>>   delete mode 100644 Documentation/devicetree/bindings/dma/mtk-uart-apdma.txt
>>
>> diff --git a/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml b/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
>> new file mode 100644
>> index 000000000000..4583c8f535b2
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/dma/mediatek,uart-dma.yaml
>> @@ -0,0 +1,112 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/dma/mediatek,uart-dma.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: MediaTek UART APDMA controller
>> +
>> +maintainers:
>> +  - Long Cheng <long.cheng@...iatek.com>
>> +
>> +description: |
>> +  The MediaTek UART APDMA controller provides DMA capabilities
>> +  for the UART peripheral bus.
>> +
>> +allOf:
>> +  - $ref: "dma-controller.yaml#"
>> +
>> +properties:
>> +  compatible:
>> +    oneOf:
>> +      - items:
>> +          - enum:
>> +              - mediatek,mt2712-uart-dma
>> +              - mediatek,mt8516-uart-dma
>> +          - const: mediatek,mt6577-uart-dma
>> +      - enum:
>> +          - mediatek,mt6577-uart-dma
>> +
>> +  reg:
>> +    minItems: 1
>> +    maxItems: 16
>> +
>> +  interrupts:
>> +    description: |
>> +      TX, RX interrupt lines for each UART APDMA channel
>> +    minItems: 1
> 
> It would be useful to have an "if:" block constraining the interrupts
> (and reg array?), if the dma-requests is missing. If you need an
> example, see length of "max8997,pmic-buck1-dvs-voltage" array in
> relation to presence of max8997,pmic-buck1-uses-gpio-dvs.
> https://elixir.bootlin.com/linux/v5.17-rc2/source/Documentation/devicetree/bindings/regulator/maxim,max8997.yaml#L259
> 
> The best would be to restrict number of interrupts to number of
> requests, but I think dtschema cannot express this.
> 

Thank you for the very much appreciated example!

I don't think that dtschema can express that without an if block... so, I'll
use that.

>> +    maxItems: 32
>> +
>> +  clocks:
>> +    description: Must contain one entry for the APDMA main clock
>> +    maxItems: 1
>> +
>> +  clock-names:
>> +    const: apdma
>> +
>> +  "#dma-cells":
>> +    const: 1
>> +    description: |
>> +      The first cell specifies the UART APDMA channel number
>> +
>> +  dma-requests:
>> +    description: |
>> +      Number of virtual channels of the UART APDMA controller
>> +    maximum: 16
>> +
>> +  mediatek,dma-33bits:
>> +    type: boolean
>> +    description: Enable 33-bits UART APDMA support
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +  - "#dma-cells"
> 
> No need for requiring dma-cells. It is coming from dma-common.yaml.

Right. Forgot about that, will fix!

> 
>> +
> 
> Best regards,
> Krzysztof