Re: [PATCH v2 02/12] dt-bindings: display: mediatek: add MT8195 hdmi bindings

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 02/11/2022 09:31, Guillaume Ranquet wrote:
> On Fri, 14 Oct 2022 18:08, Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org> wrote:
>> On 14/10/2022 11:15, Guillaume Ranquet wrote:
>>> Add mt8195 SoC bindings for hdmi and hdmi-ddc
>>>
>>> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
>>> ---
>>>  .../bindings/display/mediatek/mediatek,hdmi.yaml   | 67 +++++++++++++++++-----
>>>  .../display/mediatek/mediatek,mt8195-hdmi-ddc.yaml | 51 ++++++++++++++++
>>>  2 files changed, 104 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml b/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>>> index bdaf0b51e68c..955026cd7ca5 100644
>>> --- a/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>>> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.yaml
>>> @@ -21,26 +21,21 @@ properties:
>>>        - mediatek,mt7623-hdmi
>>>        - mediatek,mt8167-hdmi
>>>        - mediatek,mt8173-hdmi
>>> +      - mediatek,mt8195-hdmi
>>>
>>>    reg:
>>>      maxItems: 1
>>>
>>> -  interrupts:
>>> -    maxItems: 1
>>> -
>>
>> This change is not really explained in commit msg...
>>
>>>    clocks:
>>> -    items:
>>> -      - description: Pixel Clock
>>> -      - description: HDMI PLL
>>> -      - description: Bit Clock
>>> -      - description: S/PDIF Clock
>>> +    minItems: 4
>>> +    maxItems: 4
>>>
>>>    clock-names:
>>> -    items:
>>> -      - const: pixel
>>> -      - const: pll
>>> -      - const: bclk
>>> -      - const: spdif
>>> +    minItems: 4
>>> +    maxItems: 4
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>>
>>>    phys:
>>>      maxItems: 1
>>> @@ -58,6 +53,9 @@ properties:
>>>      description: |
>>>        phandle link and register offset to the system configuration registers.
>>>
>>> +  power-domains:
>>> +    maxItems: 1
>>> +
>>>    ports:
>>>      $ref: /schemas/graph.yaml#/properties/ports
>>>
>>> @@ -86,9 +84,50 @@ required:
>>>    - clock-names
>>>    - phys
>>>    - phy-names
>>> -  - mediatek,syscon-hdmi
>>>    - ports
>>>
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: mediatek,mt8195-hdmi
>>> +    then:
>>> +      properties:
>>> +        clocks:
>>> +          items:
>>> +            - description: APB
>>> +            - description: HDCP
>>> +            - description: HDCP 24M
>>> +            - description: Split HDMI
>>> +        clock-names:
>>> +          items:
>>> +            - const: hdmi_apb_sel
>>> +            - const: hdcp_sel
>>> +            - const: hdcp24_sel
>>> +            - const: split_hdmi
>>> +
>>> +      required:
>>> +        - power-domains
>>> +    else:
>>> +      properties:
>>> +        clocks:
>>> +          items:
>>> +            - description: Pixel Clock
>>> +            - description: HDMI PLL
>>> +            - description: Bit Clock
>>> +            - description: S/PDIF Clock
>>> +
>>> +        clock-names:
>>> +          items:
>>> +            - const: pixel
>>> +            - const: pll
>>> +            - const: bclk
>>> +            - const: spdif
>>> +
>>> +      required:
>>> +        - mediatek,syscon-hdmi
>>> +
>>>  additionalProperties: false
>>>
>>>  examples:
>>> diff --git a/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml b/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml
>>> new file mode 100644
>>> index 000000000000..0fe0a2a2f17f
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml
>>> @@ -0,0 +1,51 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$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
>>
>> I think I wrote it - you already have bindings for HDMI DDC. I doubt
>> that these are different and it looks like you model the bindings
>> according to your driver. That's not the way.
> 
> Hi Krzysztof,
> 
> I've made a separate binding as this new IP is integrated into the
> HDMI hw block.
> The difference it makes is that the hw is slightly simpler to describe
> as the IP doesn't
> have it's own range of registers or an interrupt line.
> 
> I can use the "legacy mediatek mtk ddc binding" if I modify it to have
> the reg and
> interrupt properties not being required for mt8195.

OK, it is reasonable - such stuff should be in commit msg, so we won't
keep asking.

> 
> Would that work better for you?
> 
>>
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>> +
>>> +  clock-names:
>>> +    items:
>>> +      - const: ddc
>>> +
>>> +  mediatek,hdmi:
>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>> +    description:
>>> +      A phandle to the mt8195 hdmi controller
>>> +
>>> +required:
>>> +  - compatible
>>> +  - clocks
>>> +  - clock-names
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +    #include <dt-bindings/interrupt-controller/irq.h>
>>> +    hdmiddc0: ddc_i2c {
>>
>> Node names should be generic - ddc.
>> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
>>
>> No underscores in node names.
>>
>> Additionally I2C devices have addresses on the bus. Why this one doesn't?
>>
> 
> This is an i2c adapter, not a device.
> And as it lives inside the HDMI hw block, I've omitted using an address here.
> 
> Is this valid? or should this be expressed differently?

What is an I2C adapter? Did you mean I2C controller (master)?

Best regards,
Krzysztof