linux-kernel - Re: [PATCH v2 01/12] dt-bindings: media: Convert MediaTek mt8173-mdp bindings to DT schema

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Message-ID: <181e1668-6efc-4dce-91e4-7b535e17dd46@collabora.com>
Date: Fri, 12 Sep 2025 10:49:34 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Chen-Yu Tsai <wenst@...omium.org>, Krzysztof Kozlowski <krzk@...nel.org>
Cc: Ariel D'Alessandro <ariel.dalessandro@...labora.com>, airlied@...il.com,
 amergnat@...libre.com, andrew+netdev@...n.ch, andrew-ct.chen@...iatek.com,
 broonie@...nel.org, chunkuang.hu@...nel.org, conor+dt@...nel.org,
 davem@...emloft.net, dmitry.torokhov@...il.com, edumazet@...gle.com,
 flora.fu@...iatek.com, heiko@...ech.de, houlong.wei@...iatek.com,
 jeesw@...fas.com, kernel@...labora.com, krzk+dt@...nel.org, kuba@...nel.org,
 lgirdwood@...il.com, linus.walleij@...aro.org,
 louisalexis.eyraud@...labora.com, luiz.dentz@...il.com,
 maarten.lankhorst@...ux.intel.com, marcel@...tmann.org,
 matthias.bgg@...il.com, mchehab@...nel.org, minghsiu.tsai@...iatek.com,
 mripard@...nel.org, p.zabel@...gutronix.de, pabeni@...hat.com,
 robh@...nel.org, sean.wang@...nel.org, simona@...ll.ch,
 support.opensource@...semi.com, tiffany.lin@...iatek.com,
 tzimmermann@...e.de, yunfei.dong@...iatek.com, devicetree@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-bluetooth@...r.kernel.org, linux-gpio@...r.kernel.org,
 linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org,
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 netdev@...r.kernel.org
Subject: Re: [PATCH v2 01/12] dt-bindings: media: Convert MediaTek mt8173-mdp
 bindings to DT schema

Il 12/09/25 10:27, Chen-Yu Tsai ha scritto:
> On Fri, Sep 12, 2025 at 2:06 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
>>
>> On Thu, Sep 11, 2025 at 12:09:50PM -0300, Ariel D'Alessandro wrote:
>>> Convert the existing text-based DT bindings for MediaTek MT8173 Media Data
>>> Path to a DT schema.
>>>
>>> Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@...labora.com>
>>> ---
>>>   .../bindings/media/mediatek,mt8173-mdp.yaml   | 169 ++++++++++++++++++
>>>   .../bindings/media/mediatek-mdp.txt           |  95 ----------
>>>   2 files changed, 169 insertions(+), 95 deletions(-)
>>>   create mode 100644 Documentation/devicetree/bindings/media/mediatek,mt8173-mdp.yaml
>>>   delete mode 100644 Documentation/devicetree/bindings/media/mediatek-mdp.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/media/mediatek,mt8173-mdp.yaml b/Documentation/devicetree/bindings/media/mediatek,mt8173-mdp.yaml
>>> new file mode 100644
>>> index 0000000000000..8ca33a733c478
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/media/mediatek,mt8173-mdp.yaml
>>> @@ -0,0 +1,169 @@
>>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/media/mediatek,mt8173-mdp.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: MediaTek MT8173 Media Data Path
>>> +
>>> +maintainers:
>>> +  - Ariel D'Alessandro <ariel.dalessandro@...labora.com>
>>> +
>>> +description:
>>> +  Media Data Path is used for scaling and color space conversion.
>>> +
>>> +properties:
>>> +  compatible:
>>> +    oneOf:
>>> +      - enum:
>>> +          - mediatek,mt8173-mdp-rdma
>>> +          - mediatek,mt8173-mdp-rsz
>>> +          - mediatek,mt8173-mdp-wdma
>>> +          - mediatek,mt8173-mdp-wrot
>>
>> Why there is no mediatek,mt8173-mdp here? What does this compatible
>> represent?
>>
>>> +      - items:
>>> +          - const: mediatek,mt8173-mdp-rdma
>>
>> Still suspicious. Device cannot be simulatanously: compatible and not
>> compatible. This is not a well known cat that has superposition of two
>> states, whenenver you look the other way.
>>
>> Maybe the old binding was incorrect, maybe the in-tree DTS is incorrect.
>> Whichever the reason, this must be investigated and documented, because
>> by standard rules this is wrong. Each wrong code needs very clear
>> explanations (and "someone did it" is not a good enough explanation).
> 
> My guess is that "mediatek,mt8173-mdp" is meant to serve as a single
> entry point for the implementation to bind the driver to. The MDP is
> a Data Pipeline and there could be multiple instances of the same
> IP block, as seen in the original example.
> 

Yeah your guess is right.

Cheers,
Angelo

> The datasheet I have doesn't cover the "RDMA" block specifically, so
> I can't say whether there is an actual difference between the two RDMA
> blocks.
> 
> 
> ChenYu
> 
>>> +          - const: mediatek,mt8173-mdp
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    minItems: 1
>>> +    maxItems: 2
>>> +
>>> +  power-domains:
>>> +    maxItems: 1
>>> +
>>> +  iommus:
>>> +    maxItems: 1
>>> +
>>> +  mediatek,vpu:
>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>> +    description:
>>> +      phandle to Mediatek Video Processor Unit for HW Codec encode/decode and
>>> +      image processing.
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - clocks
>>> +  - power-domains
>>> +
>>> +allOf:
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: mediatek,mt8173-mdp-rdma
>>> +    then:
>>> +      properties:
>>> +        clocks:
>>> +          items:
>>> +            - description: Main clock
>>> +            - description: Mutex clock
>>> +    else:
>>> +      properties:
>>> +        clocks:
>>> +          items:
>>> +            - description: Main clock
>>> +
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            enum:
>>> +              - mediatek,mt8173-mdp-rdma
>>> +              - mediatek,mt8173-mdp-wdma
>>> +              - mediatek,mt8173-mdp-wrot
>>> +    then:
>>> +      required:
>>> +        - iommus
>>> +
>>> +  - if:
>>> +      properties:
>>> +        compatible:
>>> +          contains:
>>> +            const: mediatek,mt8173-mdp
>>> +    then:
>>> +      required:
>>> +        - mediatek,vpu
>>> +
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/clock/mt8173-clk.h>
>>> +    #include <dt-bindings/memory/mt8173-larb-port.h>
>>> +    #include <dt-bindings/power/mt8173-power.h>
>>> +
>>> +    soc {
>>> +        #address-cells = <2>;
>>> +        #size-cells = <2>;
>>> +
>>> +        mdp_rdma0: rdma@...01000 {
>>> +            compatible = "mediatek,mt8173-mdp-rdma",
>>> +                         "mediatek,mt8173-mdp";
>>> +            reg = <0 0x14001000 0 0x1000>;
>>> +            clocks = <&mmsys CLK_MM_MDP_RDMA0>,
>>> +                     <&mmsys CLK_MM_MUTEX_32K>;
>>> +            power-domains = <&spm MT8173_POWER_DOMAIN_MM>;
>>> +            iommus = <&iommu M4U_PORT_MDP_RDMA0>;
>>> +            mediatek,vpu = <&vpu>;
>>> +        };
>>> +
>>> +        mdp_rdma1: rdma@...02000 {
>>> +            compatible = "mediatek,mt8173-mdp-rdma";
>>> +            reg = <0 0x14002000 0 0x1000>;
>>> +            clocks = <&mmsys CLK_MM_MDP_RDMA1>,
>>> +                     <&mmsys CLK_MM_MUTEX_32K>;
>>> +            power-domains = <&spm MT8173_POWER_DOMAIN_MM>;
>>> +            iommus = <&iommu M4U_PORT_MDP_RDMA1>;
>>> +        };
>>
>> My previous comment applies.
>>
>> Keep one or two examples.
>>
>> Best regards,
>> Krzysztof
>>