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Date: Fri, 22 Mar 2024 10:05:24 -0500
From: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Kousik Sanagavarapu <five231003@gmail.com>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-spi@vger.kernel.org,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Mark Brown <broonie@kernel.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Javier Carrasco <javier.carrasco.cruz@gmail.com>,
	Daniel Baluta <daniel.baluta@nxp.com>
Subject: Re: [PATCH v2] spi: dt-bindings: jcore,spi: convert spi-jcore to
 dtschema
Message-ID: <20240322150524.GA895852-robh@kernel.org>
References: <20240321180617.35390-1-five231003@gmail.com>
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 <5dd3237f-e0a2-4214-a63f-233e89a26b8d@linaro.org>
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On Fri, Mar 22, 2024 at 07:49:57AM +0100, Krzysztof Kozlowski wrote:
> On 22/03/2024 07:34, Krzysztof Kozlowski wrote:
> > On 22/03/2024 07:23, Kousik Sanagavarapu wrote:
> >> On Fri, 22 Mar 2024, 11:33 Krzysztof Kozlowski, <
> >> krzysztof.kozlowski@linaro.org> wrote:
> >>
> >>> On 21/03/2024 19:02, Kousik Sanagavarapu wrote:
> >>>
> >>>> +  spi-max-frequency:
> >>>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>>
> >>> No, drop. From which other SPI binding did you take it? I asked you to
> >>> look at existing code.
> >>>
> >>
> >> Without this, "make dt_binding_check" would break though, right at the
> >> position in the example where "spi-max-frequency" is used.  That was
> >> also the reason why additionalProperties was set to true in the last
> >> iteration, but after reading the doc more carefully I realized that was
> >> wrong after you pointed it out.
> >>
> >> I followed along bindings/spi/nvidia,tegra114-spi.yaml.
> > 
> > OK, you are right, the property is used here in controller node, however
> > Linux driver never parsed it. It was never used, so I propose to drop it
> > from the binding and example. You can mention in commit msg that
> > spi-max-frequency was not documented thus you drop it from the example.
> > 
> > DTS should be fixed as well. I'll send a patch for it.
> 
> Cc Daniel,
> 
> BTW, J2 core is rather odd platform to work on... Even cross compiling
> and building that DTB is tricky. If I failed, I have doubts that you
> tested the DTS with your binding.
> 
> This applies to all GSoC or some Linux Mentorship programs: I suggest to
> choose for conversion bindings with more users and bigger possible
> impact. So first I would look at ARM64 and ARMv7 platforms. We still
> have around 1000 and 3500 unique warnings about undocumented compatibles
> for ARM64 defconfig and ARM multi_v7! That's the platforms you should
> choose.
> 
> Not SuperH, ARC, or whatever with only one DTS which is difficult to
> build for regular developer.

To add to this, either ask DT maintainers what would be useful to work 
on or you can look here[1][2] to see what are the top occurring 
undocumented (by schema) compatibles.

Rob

[1] https://gitlab.com/robherring/linux-dt/-/jobs/6453674734
[2] https://gitlab.com/robherring/linux-dt/-/jobs/6453674732