linux-kernel - Re: [PATCH V7 1/2] dt-bindings: firmware: bootstats: Add the dtschema

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Message-ID: <968fb5d3-6cd8-7850-47e7-682e26f9ee5f@quicinc.com>
Date:   Wed, 5 Jul 2023 14:03:47 +0530
From:   Souradeep Chowdhury <quic_schowdhu@...cinc.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        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>, Arnd Bergmann <arnd@...db.de>
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 V7 1/2] dt-bindings: firmware: bootstats: Add the dtschema



On 7/5/2023 11:47 AM, Krzysztof Kozlowski wrote:
> On 05/07/2023 07:32, Souradeep Chowdhury wrote:
>> Add the device tree bindings for boot stats. This has 2 properties
>> pre-abl-time and abl-time which records the timestamps for boot
>> stats.
>>
>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@...cinc.com>
>> Link: https://lore.kernel.org/linux-arm-kernel/7d397e67-5d56-4975-98af-1ac9746c07f4@app.fastmail.com/
>> ---
>>   .../bindings/firmware/qcom,bootstats.yaml     | 38 +++++++++++++++++++
>>   1 file changed, 38 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/firmware/qcom,bootstats.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/firmware/qcom,bootstats.yaml b/Documentation/devicetree/bindings/firmware/qcom,bootstats.yaml
>> new file mode 100644
>> index 000000000000..22e697524058
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/firmware/qcom,bootstats.yaml
>> @@ -0,0 +1,38 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/firmware/qcom,bootstats.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Boot Stats
> 
> This explains nothing...

Ack

> 
>> +
>> +maintainers:
>> +  - Souradeep Chowdhury <quic_schowdhu@...cinc.com>
>> +
>> +description: |
> 
> Drop |

Ack

> 
>> +    Qualcomm's proprietary Android boot-loaders capture boot time
> 
> Wrong indentation.

Ack
> 
>> +    stats, like the time when the bootloader started execution and
>> +    at what point the bootloader handed over control to the kernel.
>> +    This is captured in the unit of ms in devicetree property.
>> +
>> +properties:
>> +  pre-abl-time:
>> +    description: The property to store the starting point of abl in ms.
> 
> String instead of ms? No, this is the craziest idea I saw recently. Use
> -ms suffix.
> 
>> +    $ref: /schemas/types.yaml#/definitions/string-array
>> +
>> +  abl-time:
>> +    description: The property to store the duration of abl in ms.
>> +    $ref: /schemas/types.yaml#/definitions/string-array
> 
> I have no clue what this entire binding is about. Nothing can bind to
> it, no usage explained. Properties are not used to "store the duration".
> This does not look like suitable for DT, drop entire binding.

This binding was created as per the suggestion on version 6 of the patch 
by Arnd. The idea was that these 2 devicetree properties will be used to 
populate the bootstat values from the bootloader and exposed to the user 
via /sys/firmware/devicetree/ directly.

Details in the link below:-

https://lore.kernel.org/lkml/7d397e67-5d56-4975-98af-1ac9746c07f4@app.fastmail.com/T/#mbdc9ad95fcbb5ad7b56c6996a3933899b42d982c

Can you suggest any alternative way to represent this as a binding?

> 
>> +
>> +required:
>> +  - pre-abl-time
>> +  - abl-time
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    bootstats {
>> +        pre-abl-time="17627";
>> +        abl-time="26748";
> 
> Missing spaces. Open existing DTS and look at existing coding style.

Ack

> 
> Best regards,
> Krzysztof
>