linux-kernel - Re: [PATCH v4 04/17] dt-bindings: fsi: p9-occ: Convert to json-schema

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Message-ID: <e3601656-84d3-47e1-9cbd-d2cb0dde5f51@linux.ibm.com>
Date: Wed, 1 May 2024 10:59:54 -0500
From: Eddie James <eajames@...ux.ibm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, linux-aspeed@...ts.ozlabs.org
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsi@...ts.ozlabs.org, linux-spi@...r.kernel.org,
        linux-i2c@...r.kernel.org, lakshmiy@...ibm.com, robh@...nel.org,
        krzk+dt@...nel.org, conor+dt@...nel.org, joel@....id.au,
        andrew@...econstruct.com.au, andi.shyti@...nel.org
Subject: Re: [PATCH v4 04/17] dt-bindings: fsi: p9-occ: Convert to json-schema


On 4/30/24 01:53, Krzysztof Kozlowski wrote:
> On 29/04/2024 23:01, Eddie James wrote:
>> Conver to json-schema for the OCC documentation. Also document the fact
>> that the OCC "bridge" device will often have the hwmon node as a
>> child.
>>
>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>> ---
>> Changes since v3:
>>   - Move required below other properties
>>   - Drop "occ-" in child node
>>   - Drop hwmon unit address
>>   - Complete example
>>   - Change commit message to match similar commits
>>
>>   .../devicetree/bindings/fsi/ibm,p9-occ.txt    | 16 --------
>>   .../devicetree/bindings/fsi/ibm,p9-occ.yaml   | 41 +++++++++++++++++++
>>   2 files changed, 41 insertions(+), 16 deletions(-)
>>   delete mode 100644 Documentation/devicetree/bindings/fsi/ibm,p9-occ.txt
>>   create mode 100644 Documentation/devicetree/bindings/fsi/ibm,p9-occ.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/fsi/ibm,p9-occ.txt b/Documentation/devicetree/bindings/fsi/ibm,p9-occ.txt
>> deleted file mode 100644
>> index e73358075a90..000000000000
>> --- a/Documentation/devicetree/bindings/fsi/ibm,p9-occ.txt
>> +++ /dev/null
>> @@ -1,16 +0,0 @@
>> -Device-tree bindings for FSI-attached POWER9/POWER10 On-Chip Controller (OCC)
>> ------------------------------------------------------------------------------
>> -
>> -This is the binding for the P9 or P10 On-Chip Controller accessed over FSI from
>> -a service processor. See fsi.txt for details on bindings for FSI slave and CFAM
>> -nodes. The OCC is not an FSI slave device itself, rather it is accessed
>> -through the SBE FIFO.
>> -
>> -Required properties:
>> - - compatible = "ibm,p9-occ" or "ibm,p10-occ"
>> -
>> -Examples:
>> -
>> -    occ {
>> -        compatible = "ibm,p9-occ";
>> -    };
>> diff --git a/Documentation/devicetree/bindings/fsi/ibm,p9-occ.yaml b/Documentation/devicetree/bindings/fsi/ibm,p9-occ.yaml
>> new file mode 100644
>> index 000000000000..3ab2582cb8a0
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/fsi/ibm,p9-occ.yaml
>> @@ -0,0 +1,41 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/fsi/ibm,p9-occ.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: IBM FSI-attached On-Chip Controller (OCC)
>> +
>> +maintainers:
>> +  - Eddie James <eajames@...ux.ibm.com>
>> +
>> +description:
>> +  The POWER processor On-Chip Controller (OCC) helps manage power and
>> +  thermals for the system, accessed through the FSI-attached SBEFIFO
>> +  from a service processor.
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - ibm,p9-occ
>> +      - ibm,p10-occ
>> +
>> +patternProperties:
>> +  "^hwmon":
> And now it raises questions:
> 1. Other devices on FSI bus have unit addresses, so why this does not?
> 2. This suggest only one hwmon, so ^hwmon$, which is then not a
> patternProperty but property.
> 3. But the true problem why do you even need two empty nodes? These
> should be combined into one node.


1. This is not truly on the FSI bus. It is on the SBEFIFO "bus"

2. True enough, I'll change it to property.

3. If this binding was being designed now, I'd agree with you, but the 
two nodes (occ and occ-hwmon) are already documented, I'm just changing 
to yaml here... Changing that would require a lot of changes and would 
break the two drivers.


>
>> +    type: object
>> +    $ref: /schemas/hwmon/ibm,occ-hwmon.yaml
>> +
>> +required:
>> +  - compatible
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    occ {
>> +        compatible = "ibm,p9-occ";
>> +
>> +        hwmon {
>> +            compatible = "ibm,p9-occ-hwmon";
>> +        };
>> +    };
> Best regards,
> Krzysztof
>