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From:   Guillaume Ranquet <granquet@baylibre.com>
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References: <20220919-v4-0-687f09a06dd9@baylibre.com> <20220919-v4-1-687f09a06dd9@baylibre.com>
 <20230608210504.GA3436215-robh@kernel.org>
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Date:   Fri, 9 Jun 2023 08:49:55 -0700
Message-ID: <CABnWg9tvBLH7R2Yqd_4=AOCdcHzw7Y-rigHN1jjoHe0EUGk1Bw@mail.gmail.com>
Subject: Re: [PATCH v4 1/8] dt-bindings: display: mediatek: add MT8195 hdmi bindings
To:     Rob Herring <robh@kernel.org>
Cc:     Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>, CK Hu <ck.hu@mediatek.com>,
        Jitao shi <jitao.shi@mediatek.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>, mac.shen@mediatek.com,
        stuart.lee@mediatek.com
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Precedence: bulk

On Thu, 08 Jun 2023 23:05, Rob Herring <robh@kernel.org> wrote:
>On Mon, May 29, 2023 at 04:30:58PM +0200, Guillaume Ranquet wrote:
>> Add mt8195 SoC bindings for hdmi and hdmi-ddc
>>
>> On mt8195 the ddc i2c controller is part of the hdmi IP block and thus has no
>> specific register range, power domain or interrupt, making it simpler
>> than the legacy "mediatek,hdmi-ddc" binding.
>>
>> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
>> ---
>>  .../bindings/display/mediatek/mediatek,hdmi.yaml   | 59 ++++++++++++++++++----
>>  .../display/mediatek/mediatek,mt8195-hdmi-ddc.yaml | 45 +++++++++++++++++
>>  2 files changed, 93 insertions(+), 11 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml b/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>> index b90b6d18a828..4f62e6b94048 100644
>> --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>> @@ -21,6 +21,7 @@ properties:
>>        - mediatek,mt7623-hdmi
>>        - mediatek,mt8167-hdmi
>>        - mediatek,mt8173-hdmi
>> +      - mediatek,mt8195-hdmi
>>
>>    reg:
>>      maxItems: 1
>> @@ -29,18 +30,10 @@ properties:
>>      maxItems: 1
>>
>>    clocks:
>> -    items:
>> -      - description: Pixel Clock
>> -      - description: HDMI PLL
>> -      - description: Bit Clock
>> -      - description: S/PDIF Clock
>> +    maxItems: 4
>>
>>    clock-names:
>> -    items:
>> -      - const: pixel
>> -      - const: pll
>> -      - const: bclk
>> -      - const: spdif
>> +    maxItems: 4
>>
>>    phys:
>>      maxItems: 1
>> @@ -58,6 +51,9 @@ properties:
>>      description: |
>>        phandle link and register offset to the system configuration registers.
>>
>> +  power-domains:
>> +    maxItems: 1
>> +
>>    ports:
>>      $ref: /schemas/graph.yaml#/properties/ports
>>
>> @@ -86,9 +82,50 @@ required:
>>    - clock-names
>>    - phys
>>    - phy-names
>> -  - mediatek,syscon-hdmi
>>    - ports
>>
>> +allOf:
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            const: mediatek,mt8195-hdmi
>> +    then:
>> +      properties:
>> +        clocks:
>> +          items:
>> +            - description: APB
>> +            - description: HDCP
>> +            - description: HDCP 24M
>> +            - description: Split HDMI
>> +        clock-names:
>> +          items:
>> +            - const: hdmi_apb_sel
>> +            - const: hdcp_sel
>> +            - const: hdcp24_sel
>> +            - const: split_hdmi
>> +
>> +      required:
>> +        - power-domains
>> +    else:
>> +      properties:
>> +        clocks:
>> +          items:
>> +            - description: Pixel Clock
>> +            - description: HDMI PLL
>> +            - description: Bit Clock
>> +            - description: S/PDIF Clock
>> +
>> +        clock-names:
>> +          items:
>> +            - const: pixel
>> +            - const: pll
>> +            - const: bclk
>> +            - const: spdif
>
>I don't understand how the same h/w block can have completely different
>clocks. If not the same h/w or evolution of the same h/w, then do a
>separate schema.
>

Hi Rob,

I'm not entirely sure what's the best approach here.
The IPs are different enough to warrant a separate schema IMHO.
Though CK asked me to merge both IPs together (for both schema and code).

CK might want to chime in and advocate his point of view?

>> +
>> +      required:
>> +        - mediatek,syscon-hdmi
>> +
>>  additionalProperties: false
>>
>>  examples:
>> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml b/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml
>> new file mode 100644
>> index 000000000000..84c096835b47
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml
>> @@ -0,0 +1,45 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Mediatek HDMI DDC for mt8195
>> +
>> +maintainers:
>> +  - CK Hu <ck.hu@mediatek.com>
>> +  - Jitao shi <jitao.shi@mediatek.com>
>> +
>> +description: |
>> +  The HDMI DDC i2c controller is used to interface with the HDMI DDC pins.
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - mediatek,mt8195-hdmi-ddc
>> +
>> +  clocks:
>> +    maxItems: 1
>> +
>> +  mediatek,hdmi:
>> +    $ref: /schemas/types.yaml#/definitions/phandle
>> +    description:
>> +      A phandle to the mt8195 hdmi controller
>> +
>> +required:
>> +  - compatible
>> +  - clocks
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +    #include <dt-bindings/interrupt-controller/irq.h>
>> +    hdmiddc0: i2c {
>> +      compatible = "mediatek,mt8195-hdmi-ddc";
>> +      mediatek,hdmi = <&hdmi0>;
>> +      clocks = <&clk26m>;
>
>How does one access this h/w device? There is nothing described to
>access it.
>

The device is embedded into the HDMI block and thus uses the
mediatek,hdmi phandle to access its sets of registers in the middle of
the mediatek,hdmi register range.

Hope this clarifies things,
Guillaume.

>Rob