linux-kernel - Re: [PATCH 1/2] dt-bindings: soc: mediatek: add mdp3 mutex support for mt8186

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Message-ID: <2b25912b-85d7-8804-b973-6239545d19ff@collabora.com>
Date:   Fri, 8 Jul 2022 10:28:26 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        "allen-kh.cheng" <allen-kh.cheng@...iatek.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>
Cc:     Project_Global_Chrome_Upstream_Group@...iatek.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        Xiandong Wang <xiandong.wang@...iatek.com>
Subject: Re: [PATCH 1/2] dt-bindings: soc: mediatek: add mdp3 mutex support
 for mt8186

Il 08/07/22 10:19, Matthias Brugger ha scritto:
> 
> 
> On 08/07/2022 10:14, allen-kh.cheng wrote:
>> Hi Angelo,
>>
>> On Thu, 2022-07-07 at 12:59 +0200, AngeloGioacchino Del Regno wrote:
>>> Il 07/07/22 12:41, Matthias Brugger ha scritto:
>>>>
>>>>
>>>> On 07/07/2022 10:52, AngeloGioacchino Del Regno wrote:
>>>>> Il 05/07/22 14:26, Allen-KH Cheng ha scritto:
>>>>>> Add mdp3 mutex compatible for mt8186 SoC.
>>>>>>
>>>>>> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@...iatek.com>
>>>>>> Signed-off-by: Xiandong Wang <xiandong.wang@...iatek.com>
>>>>>
>>>>>
>>>>> Please drop this commit. Adding a mdp3-mutex compatible is not
>>>>> needed here.
>>>>>
>>>>
>>>> Thanks for checking. We probably would need a fallback compatible.
>>>> We can only know
>>>> from the HW engineers that can confirm if the IP block is the same
>>>> as the disp
>>>> mutex or a different one.
>>>>
>>>> I'll drop both patches for now until things got clear.
>>>>
>>>
>>> They're located in a different iospace from each other, but either
>>> the platform
>>> data needs to *not be* joined together, or if they're together, I
>>> would not like
>>> having two different compatible strings for essentially the same
>>> thing.
>>>
>>> I would at this point prefer dropping '-disp' from 'mediatek,mt8186-
>>> disp-mutex'
>>> so that we would be able to declare two 'mediatek,mt8186-mutex' in
>>> devicetree...
>>> ...or simply have two mediatek,mt8186-disp-mutex (although logically
>>> incorrect?).
>>>
>>> Cheers,
>>> Angelo
>>>
>>
>> Thanks for your opinion.
>>
>> They are two different hardwares for different address spaces.
>>
>> I think we drop '-disp' from 'mediatek,mt8186-disp-mutex' will be
>> excessive because we also need to modify mutex node in all exited dts
>> files.
>>
>> I prefer havingg two mediatek,mt8186-disp-mutex.
>>
>> ex:
>> mutex: mutex@...01000 {
>>     compatible = "mediatek,mt8186-disp-mutex";
>>     ..
>> }
>>
>> mdp3_mutex0: mutex@...01000 {
>>     compatible = "mediatek,mt8186-disp-mutex";
>>     ...
>> }
>>
>> What do you think?
> 
> I think that's an acceptable solution.
> 

I'm a bit undecided instead, now... because from what I understand now,
the platform data fields

	.mutex_mod  and  .mutex_sof

are *not valid* for mutex at 0x1b001000 but only for the instance at 0x14001000.

If we go this way, at this point, we would be free (and allowed by the driver)
to try to set these for 0x1b001000, and to try to set MDP3 table paths on
0x14001000, which is something that shouldn't be logically allowed, as the
hardware does *not* support that.

Unless I got that wrong, and these fields for MUTEX_MOD_DISP_xxxx do exist in
the mutex instance at 0xb001000, in which case, I fully agree with Matthias.

But otherwise, I have my doubts.

Cheers,
Angelo

> Regards,
> Matthias
> 
>>
>> Best regards,
>> Allen
>>
>>>> Regards,
>>>> Matthias
>>>>
>>>>>> ---
>>>>>> .../devicetree/bindings/soc/mediatek/mediatek,mutex.yaml
>>>>>>    | 1 +
>>>>>>    1 file changed, 1 insertion(+)
>>>>>>
>>>>>> diff --git
>>>>>> a/Documentation/devicetree/bindings/soc/mediatek/mediatek,mutex
>>>>>> .yaml
>>>>>> b/Documentation/devicetree/bindings/soc/mediatek/mediatek,mutex
>>>>>> .yaml
>>>>>> index 627dcc3e8b32..234fa5dc07c2 100644
>>>>>> ---
>>>>>> a/Documentation/devicetree/bindings/soc/mediatek/mediatek,mutex
>>>>>> .yaml
>>>>>> +++
>>>>>> b/Documentation/devicetree/bindings/soc/mediatek/mediatek,mutex
>>>>>> .yaml
>>>>>> @@ -30,6 +30,7 @@ properties:
>>>>>>          - mediatek,mt8173-disp-mutex
>>>>>>          - mediatek,mt8183-disp-mutex
>>>>>>          - mediatek,mt8186-disp-mutex
>>>>>> +      - mediatek,mt8186-mdp3-mutex
>>>>>>          - mediatek,mt8192-disp-mutex
>>>>>>          - mediatek,mt8195-disp-mutex
>>>>>
>>>>>
>>>>>
>>>
>>>
>>