linux-kernel - Re: [PATCH V4 1/3] dt-bindings: sram: qcom,imem: Add Boot Stat region within IMEM

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Message-ID: <77c4ba62-1566-993b-ec33-0da2fa9936ec@linaro.org>
Date:   Thu, 4 May 2023 19:26:03 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        Souradeep Chowdhury <quic_schowdhu@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        Sibi Sankar <quic_sibis@...cinc.com>,
        Rajendra Nayak <quic_rjendra@...cinc.com>
Subject: Re: [PATCH V4 1/3] dt-bindings: sram: qcom,imem: Add Boot Stat region
 within IMEM

On 04/05/2023 09:26, Krzysztof Kozlowski wrote:
> On 04/05/2023 00:10, Caleb Connolly wrote:
>>
>>
>> On 17/04/2023 16:08, Souradeep Chowdhury wrote:
>>> All Qualcomm bootloaders log useful timestamp information related
>>> to bootloader stats in the IMEM region. Add the child node within
>>> IMEM for the boot stat region containing register address and
>>> compatible string.
>>>
>>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@...cinc.com>
>>> ---
>>>   .../devicetree/bindings/sram/qcom,imem.yaml        | 22 ++++++++++++++++++++++
>>>   1 file changed, 22 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/sram/qcom,imem.yaml b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
>>> index ba694ce..d028bed 100644
>>> --- a/Documentation/devicetree/bindings/sram/qcom,imem.yaml
>>> +++ b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
>>> @@ -49,6 +49,28 @@ patternProperties:
>>>       $ref: /schemas/remoteproc/qcom,pil-info.yaml#
>>>       description: Peripheral image loader relocation region
>>>
>>> +  "^stats@[0-9a-f]+$":
>>> +    type: object
>>> +    description:
>>> +      Imem region dedicated for storing timestamps related
>>> +      information regarding bootstats.
>>> +
>>> +    additionalProperties: false
>>> +
>>> +    properties:
>>> +      compatible:
>>> +        items:
>>> +          - enum:
>>> +              - qcom,sm8450-bootstats
>>
>> This region isn't exclusive to sm8450, it exists also on sdm845 and
>> presumably other platforms. Is there any need for an SoC specific
>> compatible?
> 
> Yes.
> https://elixir.bootlin.com/linux/v6.1-rc1/source/Documentation/devicetree/bindings/writing-bindings.rst#L42
> 
> Also see many discussions on LKML about this.

After taking another glance at the parent device (IMEM), I start to 
think that we should not be defining the device at all. The imem has the 
SoC name in it. So I think there should be a proper driver for IMEM. 
Then it will instantiate the ABL stats platform device depending on the 
SoC compat. Also this would allow us to rewrite qcom_pil_info_init() in 
a way to query IMEM instead of poking into DT directly.

-- 
With best wishes
Dmitry