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

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Date: Wed, 15 May 2024 10:02:46 -0500
From: Eddie James <eajames@...ux.ibm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, 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 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...


Thanks for your detailed review Krzysztof,

Eddie


>
>
>> commit message to indicate that I'm adding it.
>
>
> Best regards,
> Krzysztof
>