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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Wed, 20 Dec 2023 09:06:20 +0200
Message-ID: <CAA8EJppwsezPV21Uw8xTn=ra8L2jfnkHoRghDPN96O5tJsOD7A@mail.gmail.com>
Subject: Re: [PATCH v3 1/1] arm64: dts: qcom: sm8550: remove
 address/size-cells from mdss_dsi1
To: "Aiqun Yu (Maria)" <quic_aiquny@quicinc.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>, Tengfei Fan <quic_tengfan@quicinc.com>, 
	andersson@kernel.org, konrad.dybcio@linaro.org, robh+dt@kernel.org, 
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, 
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org, kernel@quicinc.com
Content-Type: text/plain; charset="UTF-8"

On Wed, 20 Dec 2023 at 02:54, Aiqun Yu (Maria) <quic_aiquny@quicinc.com> wrote:
>
>
>
> On 12/19/2023 6:21 PM, Dmitry Baryshkov wrote:
> > On Tue, 19 Dec 2023 at 12:09, Aiqun Yu (Maria) <quic_aiquny@quicinc.com> wrote:
> >>
> >>
> >>
> >> On 12/19/2023 5:41 PM, Krzysztof Kozlowski wrote:
> >>> On 19/12/2023 10:36, Aiqun Yu (Maria) wrote:
> >>>>
> >>>>
> >>>> On 12/19/2023 3:17 PM, Krzysztof Kozlowski wrote:
> >>>>> On 19/12/2023 01:31, Tengfei Fan wrote:
> >>>>>> The address/size-cells in mdss_dsi1 node have not ranges and child also
> >>>>>> have not reg, then this leads to dtc W=1 warnings:
> >>>>>
> >>>> Comments can be more readable:
> >>>> "mdss_dsi1" node don't have "ranges" or child "reg" property, while it
> >>>> have address/size-cells properties. This caused
> >>>> "avoid_unnecessary_addr_size" warning from dtb check.
> >>>> Remove address/size-cells properties for "mdss_dsi1" node.
> >>>>
> >>>>> I cannot parse it. Address/size cells never have ranges or children.
> >>>>> They cannot have. These are uint32 properties.
> >>>> Pls help to comment on the revised commit message. Every time I write a
> >>>> commit message, also takes a while for me to double confirm whether
> >>>> others can understand me correctly as well. Feel free to let us know if
> >>>> it is not readable to you. It will help us as non-English native developers.
> >>>>>
> >>>>>>
> >>>>>>      sm8550.dtsi:2937.27-2992.6: Warning (avoid_unnecessary_addr_size): /soc@0/display-subsystem@ae00000/dsi@ae96000:
> >>>>>>        unnecessary #address-cells/#size-cells without "ranges" or child "reg" property
> >>>>>>
> >>>>>>
> >>>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> >>>>>> Signed-off-by: Tengfei Fan <quic_tengfan@quicinc.com>
> >>>>>> ---
> >>>>>
> >>>>> I disagreed with the patch before. You resubmit it without really
> >>>>> addressing my concerns.
> >>>>>
> >>>>> I am not sure if this is correct fix and I want to fix all of such
> >>>>> errors (there are multiple of them) in the same way. Feel free to
> >>>>> propose common solution based on arguments.
> >>>> Per my understanding, "qcom,mdss-dsi-ctrl" driver node like "mdss_dsi1"
> >>>> don't need to have address/size-cells properties.
> >>>
> >>> Just because dtc says so? And what about bindings?
> >> I don't find any reason why "qcom,mdss-dsi-ctrl" driver node need to
> >> have address/size-cells properties. Document Bindings should also be fixed.
> >>>
> >>>> Feel free to let us know whether there is different idea of
> >>>> "address/size-cells" needed for the "qcom,mdss-dsi-ctrl" driver node.
> >>>
> >>> The bindings expressed that idea. If the binding is incorrect, fix the
> >>> binding and the DTS. If the binding is correct, provide rationale why it
> >>> somehow does not apply here etc.
> >> Our plan is to fix the bindings as well.
> >>
> >> In case you have missed the question, I just re-place it here:
> >> While there are about 22 different soc dtsi and it's document binding
> >> files needed to be fixed. Shall we fix it for all qcom related soc usage
> >> in one patch, or we'd better to split into different patches according
> >> to soc specifically?
> >
> > Don't touch the bindings unless you understand what you are doing.
> > Your patch will be NAKed. There can be a DSI panel attached to the DSI
> > host, which means there is a need for #address-cells / #size-cells.
> >
> Could you please help to elaborate more on details? Like what's the
> right example here for the "qcom,mdss-dsi-ctrl" driver node needed to
> have "#address-cells"/"#size-cells".

As I wrote, the attached DSI panels make use of #address-cells / #size-cells.

Please take a look at the sdm845-mtp.dts, which provides a complex
enough example (a panel which is attached to both DSI0 and DSI1
hosts).

> Thx to chime in that we have put a good amount of time here.

Can't quite catch you here.

> > Please stop wasting the time on dtc warning. The bindings (and the
> > file) are correct.
> I don't agree here.
> Either it is a wrong usage of "#address-cells"/"#size-cells", or dtc
> warning should be fixed with this usage take into account.
> "dtb check" will be a good guideline for developers to follow, I don't
> think it is wasting time here.

It is a guideline, but not a rule. No warnings by default is more of
the rule. W=1 enables warnings that developers have to classify and
cope with.

E.g. I don't think dtc correctly handles the case when there are both
with-address and no-address nodes (e.g. 'panel@0' and 'ports'). Note,
I might be mistaken there.

> >
>
> --
> Thx and BRs,
> Aiqun(Maria) Yu


-- 
With best wishes
Dmitry