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    SubjectRe: [PATCH v3 02/12] dt-bindings: display: mediatek: add MT8195 hdmi bindings
    On Mon, 02 Jan 2023 15:14, AngeloGioacchino Del Regno
    <angelogioacchino.delregno@collabora.com> wrote:
    >Il 02/01/23 14:38, Guillaume Ranquet ha scritto:
    >> On Mon, 26 Dec 2022 06:18, CK Hu (胡俊光) <ck.hu@mediatek.com> wrote:
    >>> Hi, Guillaume:
    >>>
    >>> On Fri, 2022-11-04 at 15:09 +0100, 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 its the legacy "mediatek,hdmi-ddc" binding.
    >>>>
    >>>> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
    >>>> ---
    >>>>
    >>>
    >>> [snip]
    >>>
    >>>> 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..2dc273689584
    >>>> --- /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
    >>>> +---
    >>>> +$id:
    >>>> https://urldefense.com/v3/__http://devicetree.org/schemas/display/mediatek/mediatek,mt8195-hdmi-ddc.yaml*__;Iw!!CTRNKA9wMg0ARbw!wwVQuq5lzW0lvUFUkVXPWT8cIu96xdkn4tMams1E55qyxEZmgV1i0WfpOlq57w$
    >>>>
    >>>> +$schema:
    >>>> https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!wwVQuq5lzW0lvUFUkVXPWT8cIu96xdkn4tMams1E55qyxEZmgV1i0WdSGOSxzw$
    >>>>
    >>>> +
    >>>> +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
    >>>> +
    >>>> + 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: i2c {
    >>>> + compatible = "mediatek,mt8195-hdmi-ddc";
    >>>> + mediatek,hdmi = <&hdmi0>;
    >>>> + clocks = <&clk26m>;
    >>>> + clock-names = "ddc";
    >>>> + };
    >>>
    >>> I think we should not have a virtual device. This ddc is part of
    >>> mt8195-hdmi device, so just keep mt8195-hdmi, and let mt8195-hdmi
    >>> driver to probe the sub driver of ddc driver.
    >>>
    >>> Regards,
    >>> CK
    >>
    >> Hi CK,
    >>
    >> Thx for your input.
    >> Though I would strongly prefer to keep the ddc as a separate "virtual device".
    >>
    >> It aligns better with the goal of reusing as much code as possible
    >> from the HDMI V1 IP,
    >> which is something you have been advocating since V1 of this patch
    >> quite some time ago
    >> and has shaped this patch.
    >>
    >> To me we are in a state that is clean and avoids branching in the hdmi
    >> common code.
    >> Would you reconsider and allow the use of that virtual device?
    >>
    >> Thx,
    >> Guillaume.
    >>
    >
    >You can as well keep the DDC as a separated driver, but register in the HDMI v1 and
    >v2 driver at probe time.
    >
    >Doing that, you won't need any devicetree node specific to any virtual device :-)
    >
    >Cheers,
    >Angelo
    >
    >

    Sure, but does it make any sense for HDMI v1?
    As the ddc in v1 is a real device which (in theory) can be reused by other IPs.

    I would see either v1 and v2 ddc exposed as a devicetree node (which
    is what I favor).
    Or v1 as a devicetree node and v2 probed directly from the hdmi code base.

    Thx,
    Guillaume.

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