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

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Date: Fri, 21 Jun 2024 12:10:00 +0100
From: Lee Jones <lee@...nel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: mfd: Explain lack of child dependency in
 simple-mfd

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@...aro.org>
> >> ---
> >>  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.

Submit it and please include the original author this time.

-- 
Lee Jones [李琼斯]