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Subject: Re: [PATCH 01/12] dt-bindings: power: Add bindings for the Mediatek
 SCPSYS power domains controller
To:     Rob Herring <robh@kernel.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc:     linux-kernel@vger.kernel.org,
        Collabora Kernel ML <kernel@collabora.com>,
        fparent@baylibre.com, drinkcat@chromium.org, hsinyi@chromium.org,
        weiyi.lu@mediatek.com, Matthias Brugger <mbrugger@suse.com>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
References: <20200910172826.3074357-1-enric.balletbo@collabora.com>
 <20200910172826.3074357-2-enric.balletbo@collabora.com>
 <20200911230255.GA2972120@bogus>
From:   Matthias Brugger <matthias.bgg@gmail.com>
Message-ID: <7a1c89b6-f483-5d57-f154-b80b72964077@gmail.com>
Date:   Mon, 14 Sep 2020 10:59:36 +0200
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On 12/09/2020 01:02, Rob Herring wrote:
> On Thu, Sep 10, 2020 at 07:28:15PM +0200, Enric Balletbo i Serra wrote:
>> The System Control Processor System (SCPSYS) has several power management
>> related tasks in the system. Add the bindings to define the power
>> domains for the SCPSYS power controller.
>>
>> Co-developed-by: Matthias Brugger <mbrugger@suse.com>
>> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>> ---
>> Dear Rob,
>>
>> I am awasre that this binding is not ready, but I prefered to send because I'm
>> kind of blocked. Compiling this binding triggers the following error:
>>
>>      mediatek,power-controller.example.dt.yaml: syscon@10006000: mfg_async@7:
>>      '#address-cells', '#size-cells', 'mfg_2d@8'
>>      do not match any of the regexes: 'pinctrl-[0-9]+'
>>
>> This happens when a definition of a power-domain (parent) contains
>> another power-domain (child), like the example. I am not sure how to
>> specify this in the yaml and deal with this, so any clue is welcome.
> 
> You just have to keep nesting schemas all the way down. Define a
> grandchild node under the child node and then all of its properties.
> 
>>
>> Thanks,
>>    Enric
>>
>>   .../power/mediatek,power-controller.yaml      | 171 ++++++++++++++++++
>>   1 file changed, 171 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml b/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>> new file mode 100644
>> index 000000000000..8be9244ad160
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/power/mediatek,power-controller.yaml
>> @@ -0,0 +1,171 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/power/mediatek,power-controller.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Mediatek Power Domains Controller
>> +
>> +maintainers:
>> +  - Weiyi Lu <weiyi.lu@mediatek.com>
>> +  - Matthias Brugger <mbrugger@suse.com>
>> +
>> +description: |
>> +  Mediatek processors include support for multiple power domains which can be
>> +  powered up/down by software based on different application scenes to save power.
>> +
>> +  IP cores belonging to a power domain should contain a 'power-domains'
>> +  property that is a phandle for SCPSYS node representing the domain.
>> +
>> +properties:
>> +  $nodename:
>> +    pattern: "^syscon@[0-9a-f]+$"
>> +
>> +  compatible:
>> +    items:
>> +      - enum:
>> +        - mediatek,mt8173-power-controller
>> +      - const: syscon
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +patternProperties:
>> +  "^.*@[0-9]$":
> 
> Node names should be generic:
> 
> power-domain@
> 

Enric correct me if I'm wrong, if we want to see the power domains in debugfs, 
they are listed by their name. If all are called power-domain then the listing 
is pretty much useless.

>> +    type: object
>> +    description: |
>> +      Represents the power domains within the power controller node as documented
>> +      in Documentation/devicetree/bindings/power/power-domain.yaml.
>> +
>> +    properties:
>> +      reg:
>> +        description: |
>> +          Power domain index. Valid values are defined in:
>> +              "include/dt-bindings/power/mt8173-power.h" - for MT8173 type power domain.
>> +        maxItems: 1
>> +
>> +      '#power-domain-cells':
>> +        description:
>> +          Documented by the generic PM Domain bindings in
>> +          Documentation/devicetree/bindings/power/power-domain.yaml.
> 
> No need to redefine a common property. This should define valid values
> for it.
> 
>> +
>> +      clocks:
>> +        description: |
>> +          A number of phandles to clocks that need to be enabled during domain
>> +          power-up sequencing.
> 
> No need to redefine 'clocks'. You need to define how many, what each one
> is, and the order.
> 

Do you mean we have to define each clock for each power domain of each SoC?

>> +
>> +      clock-names:
>> +        description: |
>> +          List of names of clocks, in order to match the power-up sequencing
>> +          for each power domain we need to group the clocks by name. BASIC
>> +          clocks need to be enabled before enabling the corresponding power
>> +          domain, and should not have a '-' in their name (i.e mm, mfg, venc).
>> +          SUSBYS clocks need to be enabled before releasing the bus protection,
>> +          and should contain a '-' in their name (i.e mm-0, isp-0, cam-0).
>> +
>> +          In order to follow properly the power-up sequencing, the clocks must
>> +          be specified by order, adding first the BASIC clocks followed by the
>> +          SUSBSYS clocks.
> 
> You need to define the names.
> 
>> +
>> +      mediatek,infracfg:
>> +        $ref: /schemas/types.yaml#definitions/phandle
>> +        description: phandle to the device containing the INFRACFG register range.
>> +
>> +      mediatek,smi:
>> +        $ref: /schemas/types.yaml#definitions/phandle
>> +        description: phandle to the device containing the SMI register range.
>> +
>> +    required:
>> +      - reg
>> +      - '#power-domain-cells'
>> +
>> +    additionalProperties: false
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/mt8173-clk.h>
>> +    #include <dt-bindings/power/mt8173-power.h>
>> +
>> +    soc {
>> +        #address-cells = <2>;
>> +        #size-cells = <2>;
>> +
>> +        scpsys: syscon@10006000 {
>> +            compatible = "mediatek,mt8173-power-controller", "syscon";

The power domain controller is just one funcionality the SCPSYS block can 
provide. I think it should be child of the SCPSYS.

Regards,
Matthias