linux-kernel - Re: [PATCH v3 06/21] dt-bindings: power: mediatek: Add bindings for MediaTek SCPSYS

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Message-ID: <bba2bbbd-834e-d70a-91a4-6f2e989a6647@linaro.org>
Date:   Thu, 21 Jul 2022 08:34:10 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Tinghan Shen <tinghan.shen@...iatek.com>,
        Yong Wu <yong.wu@...iatek.com>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Lee Jones <lee.jones@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        MandyJH Liu <mandyjh.liu@...iatek.com>
Cc:     iommu@...ts.linux.dev, linux-mediatek@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v3 06/21] dt-bindings: power: mediatek: Add bindings for
 MediaTek SCPSYS

On 21/07/2022 05:05, Tinghan Shen wrote:
> On Wed, 2022-07-20 at 19:35 +0200, Krzysztof Kozlowski wrote:
>> On 20/07/2022 14:30, Tinghan Shen wrote:
>>> The System Control Processor System (SCPSYS) has several power
>>> management related tasks in the system. Add the bindings for it.
>>>
>>> Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
>>> ---
>>>  .../bindings/mfd/mediatek,mt8195-scpsys.yaml  | 68 +++++++++++++++++++
>>>  1 file changed, 68 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/mfd/mediatek,mt8195-scpsys.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/mfd/mediatek,mt8195-scpsys.yaml
>>> b/Documentation/devicetree/bindings/mfd/mediatek,mt8195-scpsys.yaml
>>> new file mode 100644
>>> index 000000000000..4117a6dbc19c
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/mfd/mediatek,mt8195-scpsys.yaml
>>> @@ -0,0 +1,68 @@
>>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>>> +%YAML 1.2
>>> +---
>>> +$id: 
>>> https://urldefense.com/v3/__http://devicetree.org/schemas/mfd/mediatek,mt8195-scpsys.yaml*__;Iw!!CTRNKA9wMg0ARbw!y63E-9qbCW_vyn8RrsCCs7YvZ7NxKqFT7l8C0ZZirEW95Ec0ce3lwegsSq51wrjtz8GjVSpkK-omCBP5CKx1l0WESQ$
>>>  
>>> +$schema: 
>>> https://urldefense.com/v3/__http://devicetree.org/meta-schemas/core.yaml*__;Iw!!CTRNKA9wMg0ARbw!y63E-9qbCW_vyn8RrsCCs7YvZ7NxKqFT7l8C0ZZirEW95Ec0ce3lwegsSq51wrjtz8GjVSpkK-omCBP5CKzzr9p82Q$
>>>  
>>> +
>>> +title: MediaTek System Control Processor System
>>> +
>>> +maintainers:
>>> +  - MandyJH Liu <mandyjh.liu@...iatek.com>
>>> +
>>> +description:
>>> +  MediaTek System Control Processor System (SCPSYS) has several
>>> +  power management tasks. The tasks include MTCMOS power
>>> +  domain control, thermal measurement, DVFS, etc.
>>> +
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - enum:
>>> +          - mediatek,mt8167-scpsys
>>> +          - mediatek,mt8173-scpsys
>>> +          - mediatek,mt8183-scpsys
>>> +          - mediatek,mt8192-scpsys
>>> +          - mediatek,mt8195-scpsys
>>> +      - const: syscon
>>> +      - const: simple-mfd
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +patternProperties:
>>> +  "^power-controller(@[0-9a-f]+)?$":
>>> +    $ref: /schemas/power/mediatek,power-controller.yaml#
>>
>> We talked that unit address might be useful but it was with an
>> assumption that you will actually use it. I think you don't use it, so
>> it is kind of meaningless now... unless you plan to use it?
> 
> I tried to add the offset in the node name, but the binding check reports this message.
>  	
>     power-controller@0: node has a unit name, but no reg or ranges property

Why would you add unit address without reg? What point would it solve?

> After considering the fact of mt8195 power controller HW resides in scpsys and the current power
> domain driver doesn't support parsing the register address seperated from scpsys, I decide to
> keep the power controller node as in v2 to pass the binding check and compatible with driver.

Then adding unit addresses in bindings has no point.


Best regards,
Krzysztof