linux-kernel - Re: [PATCH v3 1/5] dt-bindings: Powerzone new bindings

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Date:   Thu, 2 Dec 2021 17:25:37 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     robh@...nel.org, arnd@...aro.org, heiko@...ech.de,
        rjw@...ysocki.net, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        lukasz.luba@....com, Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v3 1/5] dt-bindings: Powerzone new bindings

On 02/12/2021 15:42, Ulf Hansson wrote:
> On Wed, 1 Dec 2021 at 17:41, Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
>>
>> The proposed bindings are describing a set of powerzones.
>>
>> A power zone is the logical name for a component which is capable of
>> power capping and where we can measure the power consumption.
>>
>> A power zone can aggregate several power zones in terms of power
>> measurement and power limitations. That allows to apply power
>> constraint to a group of components and let the system balance the
>> allocated power in order to comply with the constraint.
>>
>> The ARM System Control and Management Interface (SCMI) can provide a
>> power zone description.
>>
>> The powerzone semantic is also found on the Intel platform with the
>> RAPL register.
>>
>> The Linux kernel powercap framework deals with the powerzones:
>>
>> https://www.kernel.org/doc/html/latest/power/powercap/powercap.html
>>
>> The powerzone can also represent a group of children powerzones, hence
>> the description can result on a hierarchy. Such hierarchy already
>> exists with the hardware or can be represented and computed from the
>> kernel.
>>
>> The hierarchical description was initially proposed but not desired
>> given there are other descriptions like the power domain proposing
>> almost the same description.
>>
>> https://lore.kernel.org/all/CAL_JsqLuLcHj7525tTUmh7pLqe7T2j6UcznyhV7joS8ipyb_VQ@mail.gmail.com/
>>
>> The description gives the power constraint dependencies to apply on a
>> specific group of logically or physically aggregated devices. They do
>> not represent the physical location or the power domains of the SoC
>> even if the description could be similar.
>>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: Ulf Hansson <ulf.hansson@...aro.org>
>> Cc: Rob Herring <robh+dt@...nel.org>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> 
> This looks good to me, feel free to add:
> 
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Thanks Ulf for your time to review these bindings



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