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Date:   Thu, 4 May 2023 18:27:45 +0530
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Subject: Re: [PATCH v3 02/18] remoteproc: qcom: Move minidump specific data to
 qcom_minidump.h
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To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        <agross@kernel.org>, <andersson@kernel.org>,
        <konrad.dybcio@linaro.org>, <corbet@lwn.net>,
        <keescook@chromium.org>, <tony.luck@intel.com>,
        <gpiccoli@igalia.com>, <catalin.marinas@arm.com>,
        <will@kernel.org>, <krzysztof.kozlowski+dt@linaro.org>,
        <robh+dt@kernel.org>, <linus.walleij@linaro.org>,
        <linux-gpio@vger.kernel.org>, <srinivas.kandagatla@linaro.org>
CC:     <linux-arm-msm@vger.kernel.org>,
        <linux-remoteproc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-hardening@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linux-doc@vger.kernel.org>
References: <1683133352-10046-1-git-send-email-quic_mojha@quicinc.com>
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 <1a4f4b55-6284-6149-4c7b-7b45fa1de291@linaro.org>
From:   Mukesh Ojha <quic_mojha@quicinc.com>
In-Reply-To: <1a4f4b55-6284-6149-4c7b-7b45fa1de291@linaro.org>
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On 5/4/2023 6:06 PM, Krzysztof Kozlowski wrote:
> On 04/05/2023 14:26, Mukesh Ojha wrote:
>>
>>
>> On 5/4/2023 5:33 PM, Krzysztof Kozlowski wrote:
>>> On 04/05/2023 13:58, Mukesh Ojha wrote:
>>>>
>>>>
>>>> On 5/4/2023 5:08 PM, Krzysztof Kozlowski wrote:
>>>>> On 03/05/2023 19:02, Mukesh Ojha wrote:
>>>>>> Move minidump specific data types and macros to a separate internal
>>>>>> header(qcom_minidump.h) so that it can be shared among different
>>>>>> Qualcomm drivers.
>>>>>
>>>>> No, this is not internal header. You moved it to global header.
>>>>>
>>>>> There is no reason driver internals should be exposed to other unrelated
>>>>> subsystems.
>>>>>
>>>>>>
>>>>>> There is no change in functional behavior after this.
>>>>>
>>>>> It is. You made all these internal symbols available to others.
>>>>>
>>>>>>
>>>>>
>>>>> This comes without justification why other drivers needs to access
>>>>> private and internal data. It does not look correct design. NAK.
>>>>
>>>> Thanks for catching outdated commit text, will fix the commit with
>>>> more descriptive reasoning.
>>>>
>>>> It has to be global so that co-processor minidump and apss minidump can
>>>> share data structure and they are lying in different directory.
>>>>
>>>
>>> Then you should not share all the internals of memory layout but only
>>> few pieces necessary to talk with minidump driver. The minidump driver
>>> should organize everything how it wants.
>>
>> These are core data structure which is shared with boot firmware and the
>> one's are moved here all are required by minidump driver .
> 
> I am not sure if I understand correctly. If they are all required by
> minidump driver, then this must not be in include, but stay with
> minidump. Remoteproc then should not touch it.
> 
> I don't understand why internals of minidump should be important for
> remoteproc. If they are, means you broken encapsulation.
> 
>>
>> If you follow here[1], i raised by concern to make this particular one's
>> as private and later to avoid confusion went with single header.
>> But if others agree, I will keep the one that get shared with minidump
>> as separate one or if relative path of headers are allowed that can make
>> it private between these drivers(which i don't think, will be allowed or
>> recommended).
> 
> Let's be specific: why MD_REGION_VALID must be available for remoteproc
> or any other driver after introducing qcom minidump driver?

Forget about this driver for a moment.

I am not sure  how much you know about existing qcom_minidump()
implementation and why is it there in first place in remoteproc
code in driver/remoteproc/qcom_common.c

The idea is, remoteproc co-processor like adsp/cdsp etc. may have their
static predefined region (segments) to be collected on their crash which 
is what exactly existing qcom_minidump() is doing.

Now, after this minidump series, APSS (linux) will have it's
own of collecting linux client region independent of whether
remoteproc minidump collection.

I think, are you hinting to move all minidump related code from 
remoteproc to qcom_minidump driver, is this what are you trying
to say ?

-- Mukesh
> 
> 
> Best regards,
> Krzysztof
>