Re: [PATCH v3 1/1] arm64: dts: qcom: sm8550: remove address/size-cells from mdss_dsi1

[Aiqun Yu (Maria)]

On 12/20/2023 3:06 PM, Dmitry Baryshkov wrote:
> On Wed, 20 Dec 2023 at 02:54, Aiqun Yu (Maria) <quic_aiquny@xxxxxxxxxxx> wrote:
> > On 12/19/2023 6:21 PM, Dmitry Baryshkov wrote:
> > > On Tue, 19 Dec 2023 at 12:09, Aiqun Yu (Maria) <quic_aiquny@xxxxxxxxxxx> 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@xxxxxxxxxx>
> > > > > > > > Signed-off-by: Tengfei Fan <quic_tengfan@xxxxxxxxxxx>
> > > > > > > > ---
> > > > > > >
> > > > > > > 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).
I can see the panel example now.
While panel@0 likely node is not at in the binding that I've checked. 
There are quite a few of binding document about the same driver. I 
checked 5 of the bindings document and moste of them are alike, and 
don't have the panel example.:(
> > 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.
Now I understand the issue, here is some thinking from my end, and 
welcome others to chime in with more ideas:
1. Only put "#address-cells" "#size-cells" right before node of panel@0.
2. Align current binding document with "panel@0" examples.
3. Too many bindings files for driver "qcom,mdss-dsi-ctrl", shall we 
align them into 1 binding files.
4. enhance the dtc warning check if we still want to have 
"#address-cells" "#size-cells" even if there is no "panel@0" attached.

@krzy here I try to answer your comments here as well.
I am disagree on leave the warning as it is. And want to do something to 
improve this. Ideas above.
Let me know if any comments is not right addressed from your comments.
> > >
> >
> > --
> > Thx and BRs,
> > Aiqun(Maria) Yu

--
Thx and BRs,
Aiqun(Maria) Yu