linux-kernel - Re: [PATCH 07/13] dt-bindings: media: camss: Add qcom,sm8550-camss binding

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Message-ID: <18fd8a2c-0563-49a0-b2a4-78f0005576e9@linaro.org>
Date: Mon, 30 Sep 2024 11:32:05 +0300
From: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 Depeng Shao <quic_depengs@...cinc.com>,
 Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>, rfoss@...nel.org,
 todor.too@...il.com, bryan.odonoghue@...aro.org, mchehab@...nel.org,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org
Cc: linux-arm-msm@...r.kernel.org, linux-media@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel@...cinc.com, Yongsheng Li <quic_yon@...cinc.com>
Subject: Re: [PATCH 07/13] dt-bindings: media: camss: Add qcom,sm8550-camss
 binding

On 9/30/24 10:26, Krzysztof Kozlowski wrote:
> On 25/09/2024 17:13, Depeng Shao wrote:
>> Hi Vladimir,
>>
>> On 9/6/2024 11:56 PM, Vladimir Zapolskiy wrote:
>>
>>>> +            compatible = "qcom,sm8550-camss";
>>>> +
>>>> +            reg = <0 0x0acb7000 0 0xd00>,
>>>> +                  <0 0x0acb9000 0 0xd00>,
>>>> +                  <0 0x0acbb000 0 0xd00>,
>>>> +                  <0 0x0acca000 0 0xa00>,
>>>> +                  <0 0x0acce000 0 0xa00>,
>>>> +                  <0 0x0acb6000 0 0x1000>,
>>>> +                  <0 0x0ace4000 0 0x2000>,
>>>> +                  <0 0x0ace6000 0 0x2000>,
>>>> +                  <0 0x0ace8000 0 0x2000>,
>>>> +                  <0 0x0acea000 0 0x2000>,
>>>> +                  <0 0x0acec000 0 0x2000>,
>>>> +                  <0 0x0acee000 0 0x2000>,
>>>> +                  <0 0x0acf0000 0 0x2000>,
>>>> +                  <0 0x0acf2000 0 0x2000>,
>>>> +                  <0 0x0ac62000 0 0xf000>,
>>>> +                  <0 0x0ac71000 0 0xf000>,
>>>> +                  <0 0x0ac80000 0 0xf000>,
>>>> +                  <0 0x0accb000 0 0x2800>,
>>>> +                  <0 0x0accf000 0 0x2800>;
>>>
>>> Please sort the list above in numerical order, this will change positions
>>> of "vfe_lite0", "vfe_lite1" etc.
>>>
>>> Another note, since it's not possible to map less than a page, so I believe
>>> it might make sense to align all sizes to 0x1000.
> 
> And if Linux behavior changes then are you going to rewrite all the DTS
> for new size?

If Linux behaves properly with page size alignments today, then the selected
page size alignment for AMBA device IO memory regions is correct, hence any
future change from the correct IP device description to another one will be
invalid or noop.

There is nothing to worry about, I believe.

> No, the sizes reflect hardware register layout, not concept of pages.
> 

Absolutely they do. It might be a coincidence that both are aligned in
this particular case or another one.

> I don't think that we should be coming with more nitpicky ideas, one
> month after the patch was sent and reviewed.

The change is not yet ready to be accepted from the technical perspective.

--
Best wishes,
Vladimir