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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <596c4ed6-bf3d-4406-8b28-2b34548520d1@linaro.org>
Date: Wed, 20 Dec 2023 12:20:01 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: "Aiqun Yu (Maria)" <quic_aiquny@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Tengfei Fan <quic_tengfan@...cinc.com>, andersson@...nel.org,
 konrad.dybcio@...aro.org, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, kernel@...cinc.com
Subject: Re: [PATCH v3 1/1] arm64: dts: qcom: sm8550: remove
 address/size-cells from mdss_dsi1

On 20/12/2023 11:33, Aiqun Yu (Maria) wrote:
>>>>
>>>> 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. 

"Likely not" is not the same as "cannot".

> There are quite a few of binding document about the same driver. I 

You keep mixing drivers, bindings and devices which does not help this
discussion. I really do not understand above sentence.

> checked 5 of the bindings document and moste of them are alike, and 
> don't have the panel example.:(

Example like the example DTS in the binding? What does it have to do
with anything here? What are we talking here about?

>>
>>> 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.

Examples? Again, about what examples are you talking? Mixing terminology
does not help this discussion, so let's be specific:
Touching examples just because you want, without valid reason: no

> 3. Too many bindings files for driver "qcom,mdss-dsi-ctrl", shall we 
> align them into 1 binding files.

You are joking right? First of all, there is no driver
"qcom,mdss-dsi-ctrl". Don't mix the terms, because it does not help the
discussion. Second, please read previous discussions related to these
bindings.

> 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.

You want to do something without understanding the problem which results
in random band-aids over some warning. Instead, please dig deeper to
understand the problem and then propose solution.

Best regards,
Krzysztof