linux-kernel - Re: [PATCH v5 5/9] dt-bindings: fsi: Document the FSI controller common properties

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Date: Fri, 17 May 2024 11:17:41 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Eddie James <eajames@...ux.ibm.com>, linux-fsi@...ts.ozlabs.org
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, robh@...nel.org, joel@....id.au,
 andrew@...econstruct.com.au
Subject: Re: [PATCH v5 5/9] dt-bindings: fsi: Document the FSI controller
 common properties

On 15/05/2024 17:02, Eddie James wrote:
> 
> On 5/15/24 09:35, Krzysztof Kozlowski wrote:
>> On 15/05/2024 16:28, Eddie James wrote:
>>> On 5/15/24 09:18, Krzysztof Kozlowski wrote:
>>>> On 14/05/2024 21:54, Eddie James wrote:
>>>>> Since there are multiple FSI controllers documented, the common
>>>>> properties should be documented separately and then referenced
>>>>> from the specific controller documentation.
>>>>>
>>>>> Signed-off-by: Eddie James <eajames@...ux.ibm.com>
>>>>> ---
>>>>> Changes since v4:
>>>>>    - Add interrupt controller properties
>>>>>    - Add clock-frequency property to FSI controller and CFAM
>>>>>    - Add detail to chip-id property description
>>>>>
>>>>>    .../bindings/fsi/fsi-controller.yaml          | 66 +++++++++++++++++++
>>>>>    1 file changed, 66 insertions(+)
>>>>>    create mode 100644 Documentation/devicetree/bindings/fsi/fsi-controller.yaml
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/fsi/fsi-controller.yaml b/Documentation/devicetree/bindings/fsi/fsi-controller.yaml
>>>>> new file mode 100644
>>>>> index 0000000000000..8620e4da6de77
>>>>> --- /dev/null
>>>>> +++ b/Documentation/devicetree/bindings/fsi/fsi-controller.yaml
>>>>> @@ -0,0 +1,66 @@
>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>> +%YAML 1.2
>>>>> +---
>>>>> +$id: http://devicetree.org/schemas/fsi/fsi-controller.yaml#
>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>> +
>>>>> +title: FSI Controller Common Properties
>>>>> +
>>>>> +maintainers:
>>>>> +  - Eddie James <eajames@...ux.ibm.com>
>>>>> +
>>>>> +description:
>>>>> +  FSI (FRU (Field Replaceable Unit) Service Interface) is a two wire bus. The
>>>>> +  FSI bus is connected to a CFAM (Common FRU Access Macro) which contains
>>>>> +  various engines such as I2C controllers, SPI controllers, etc.
>>>>> +
>>>>> +properties:
>>>>> +  "#address-cells":
>>>>> +    const: 2
>>>>> +
>>>>> +  "#size-cells":
>>>>> +    const: 0
>>>>> +
>>>>> +  '#interrupt-cells':
>>>>> +    const: 1
>>>>> +
>>>>> +  clock-frequency:
>>>>> +    minimum: 1
>>>>> +    maximum: 200000000
>>>> This is a deprecated property in general. Why did it appear? It does not
>>>> exist in current bindings and nothing in commit msg suggests changes in
>>>> the bindings themselves.
>>>
>>> OK, is there some document that describes what properties are
>>> deprecated? Because it's used all over the place in the bindings. Anyway
>> dtschema: dtschema/schemas/clock/clock.yaml
>>
>> buses anyway should use bus-frequency but it is also legacy one.
>>
>>> I need this property, I can rename it if you like. I can also update the
>> Why do you need it? Why clocks cannot be chosen by drivers and initial
>> state selected by assigned-clock-rates?
> 
> 
> Well, I could use assigned-clock-rates, though it seems like I'd then 
> have to implement the clock provider framework for both the FSI 
> controller driver and the CFAM driver, which is a lot of extra work. FSI 
> controller isn't really a clock provider, it's a bus like i2c (which 
> uses clock-frequency), so it doesn't quite fit in my opinion...

OK, it's fine in such case.

Best regards,
Krzysztof