Re: [PATCH] dt-bindings: mfd: Explain lack of child dependency in simple-mfd

From: Krzysztof Kozlowski
Date: Sun Jun 23 2024 - 03:21:36 EST


On 21/06/2024 13:10, Lee Jones wrote:
> On Thu, 20 Jun 2024, Krzysztof Kozlowski wrote:
>
>> On 20/06/2024 19:17, Lee Jones wrote:
>>> On Sun, 16 Jun 2024, Krzysztof Kozlowski wrote:
>>>
>>>> Common mistake of usage of 'simple-mfd' compatible is a dependency of
>>>> children on resources acquired and managed by the parent, e.g. clocks.
>>>> Extend the simple-mfd documentation to cover this case.
>>>>
>>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>>>> ---
>>>> Documentation/devicetree/bindings/mfd/mfd.txt | 13 +++++++------
>>>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/mfd/mfd.txt b/Documentation/devicetree/bindings/mfd/mfd.txt
>>>> index 336c0495c8a3..98b4340b65f3 100644
>>>> --- a/Documentation/devicetree/bindings/mfd/mfd.txt
>>>> +++ b/Documentation/devicetree/bindings/mfd/mfd.txt
>>>> @@ -18,12 +18,13 @@ A typical MFD can be:
>>>> Optional properties:
>>>>
>>>> - compatible : "simple-mfd" - this signifies that the operating system should
>>>> - consider all subnodes of the MFD device as separate devices akin to how
>>>> - "simple-bus" indicates when to see subnodes as children for a simple
>>>> - memory-mapped bus. For more complex devices, when the nexus driver has to
>>>> - probe registers to figure out what child devices exist etc, this should not
>>>> - be used. In the latter case the child devices will be determined by the
>>>> - operating system.
>>>> + consider all subnodes of the MFD device as separate and independent devices
>>>> + akin to how "simple-bus" indicates when to see subnodes as children for a
>>>> + simple memory-mapped bus. "Independent devices" means that children do not
>>>
>>> I'm not against the change, but I think it can be phased better.
>>>
>>> Quoting the new part and going on to explain what you mean by it doesn't
>>> flow very well. Are you able to massage it so it reads a little more
>>> nicely please?
>>
>> Does this feels better?
>>
>> compatible : "simple-mfd" - this signifies that the operating system
>> should consider all subnodes of the MFD device as separate and
>> independent devices, so not needing any resources to be provided by the
>> parent device. Similarly to how "simple-bus" indicates when to see
>> subnodes as children for a simple memory-mapped bus.
>>
>> For more complex devices, when the nexus driver has to probe registers
>> to figure out what child devices exist etc, this should not be used. In
>> the latter case the child devices will be determined by the operating
>> system.
>
> Flows a lot better, yes.

Sure.

>
> Submit it and please include the original author this time.

Everything is scripted, so you ask me for additional, manual steps just
to find the author and then Cc-them. I'll do it but it would be much
easier if the interested party added themself as reviewer or maintainer
of the binding.

>

Best regards,
Krzysztof