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Date: Thu, 28 Dec 2023 16:44:24 +0800
From: ChiYuan Huang <cy_huang@richtek.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
CC: Jonathan Cameron <jic23@kernel.org>, Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>, Rob Herring <robh+dt@kernel.org>, Uwe
 =?iso-8859-1?Q?Kleine-K=F6nig?= <u.kleine-koenig@pengutronix.de>,
	<linux-iio@vger.kernel.org>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] dt-bindings: iio: adc: rtq6056: add support for the
 whole RTQ6056 family
Message-ID: <20231228084424.GA18878@linuxcarl2.richtek.com>
References: <1703562468-29052-1-git-send-email-cy_huang@richtek.com>
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 <0f1f0991-9ad9-4216-afc8-8340eddb1ad9@linaro.org>
 <20231228031929.GA32046@linuxcarl2.richtek.com>
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User-Agent: Mutt/1.5.21 (2010-09-15)

Hi, Krzysztof:
On Thu, Dec 28, 2023 at 09:06:30AM +0100, Krzysztof Kozlowski wrote:
> On 28/12/2023 08:58, ChiYuan Huang wrote:
> > On Thu, Dec 28, 2023 at 08:09:35AM +0100, Krzysztof Kozlowski wrote:
> >> On 28/12/2023 04:19, ChiYuan Huang wrote:
> >>> On Tue, Dec 26, 2023 at 01:12:50PM +0100, Krzysztof Kozlowski wrote:
> >>>> On 26/12/2023 12:19, ChiYuan Huang wrote:
> >>>>> On Tue, Dec 26, 2023 at 10:18:47AM +0100, Krzysztof Kozlowski wrote:
> >>>>>> On 26/12/2023 04:47, cy_huang@richtek.com wrote:
> >>>>>>> From: ChiYuan Huang <cy_huang@richtek.com>
> >>>>>>>
> >>>>>>> Add compatible support for RTQ6053 and RTQ6059.
> >>>>>>>
> >>>>>>> Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> >>>>>>> ---
> >>>>>>>  .../devicetree/bindings/iio/adc/richtek,rtq6056.yaml         | 5 ++++-
> >>>>>>>  1 file changed, 4 insertions(+), 1 deletion(-)
> >>>>>>>
> >>>>>>> diff --git a/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> >>>>>>> index 88e008629ea8..d1e1f36d1972 100644
> >>>>>>> --- a/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> >>>>>>> +++ b/Documentation/devicetree/bindings/iio/adc/richtek,rtq6056.yaml
> >>>>>>> @@ -25,7 +25,10 @@ description: |
> >>>>>>>  
> >>>>>>>  properties:
> >>>>>>>    compatible:
> >>>>>>> -    const: richtek,rtq6056
> >>>>>>> +    enum:
> >>>>>>> +      - richtek,rtq6053
> >>>>>>> +      - richtek,rtq6056
> >>>>>>
> >>>>>> Aren't these devices compatible? Your driver change says they are, so
> >>>>>> express compatibility with list here (and oneOf).
> >>>>>>
> >>>>> Thanks, I try to take other binding as the reference. One more question.
> >>>>> If rtq6053 is compatible with rtq6056, there's only chip package type difference.
> >>>>> Do I need to seperate it into a dedicated enum element?
> >>>>> Or just put it into one item and said this part number is compatible with rtq6056? 
> >>>>
> >>>> See example-schema. You need enum and items, both in oneOf:.
> >>>>
> >>> After reading the 'example-schema', I Still cannot understand what the special case items
> >>> means.
> >>
> >> What is "special case items"?
> >>
> > I may misunderstand something. The special case is the 'fallback' that you mentaioned in
> > the last.
> >>>
> >>> But in my case, is the below change correct?
> >>> [Diff]
> >>> properties:
> >>>    compatible:
> >>> -    enum:
> >>> -      - richtek,rtq6053
> >>> -      - richtek,rtq6056
> >>> -      - richtek,rtq6059
> >>> +    oneOf:
> >>> +      - items:
> >>> +          - enum:
> >>> +              - richtek,rtq6053
> >>> +              - richtek,rtq6056
> >>> +              - richtek,rtq6059
> >>
> >> This changes nothing, you still have just one item. The example-schema
> >> has exactly that case, so why you are coding it differently?
> >>
> >> Anyway, test your DTS with the fallback, you will see that above does
> >> not work.
> >>
> > I rewrite the below one and tested. it seems correct.
> > 
> > [Diff]
> >    compatible:
> > -    enum:
> > -      - richtek,rtq6053
> > -      - richtek,rtq6056
> > -      - richtek,rtq6059
> > +    oneOf:
> > +      - enum:
> > +          - richtek,rtq6053
> > +          - richtek,rtq6059
> > +      - items:
> > +          - const: richtek,rtq6056
> 
> You still need two items here to express compatibility. What is
> compatible with what? It must be rtq6053 compatible with rtq6056,
> because you cannot break the ABI, can you?
> 
> > 
> > Just one more question. If rtq6053 is fully compatibie with rtq6056, does it need to be put
> > into oneOf enum or be just put into items enum and use the 'fallback' mechanism?
> 
> The fallback is just a term. The point is to have a list of two
> compatibles. See: Devicetree specification, writing-bindings and
> numerous presentations about writing DTS.
> 
> > 
> > If so, the 'richtek,rtq6053' in of_device_id match can be removed. Though it just remove
> > one line, but less-changed would be better.
> 
> The device using fallback should be removed the driver of_device_id, so
> 6053 goes away.
>
Thanks for all the information. If not misunderstanding, I'll remove "dt match id" for 6053.

And the binding fix in v2 will be 
 properties:
   compatible:
-    enum:
-      - richtek,rtq6053
-      - richtek,rtq6056
-      - richtek,rtq6059
+    oneOf:
+      - enum:
+          - richtek,rtq6056
+          - richtek,rtq6059
+      - items:
+          - enum:
+              - richtek,rtq6053
+          - const: richtek,rtq6056
 
This make the 6053 compatible with 6056 with DT fallback.

> Best regards,
> Krzysztof
>