linux-kernel - Re: [RFC][PATCH 1/2] dt-bindings: power: add Energy Model bindings

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Message-ID: <e979397d-c522-e0da-b997-16609fe308c5@arm.com>
Date:   Tue, 22 Feb 2022 11:03:51 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-kernel@...r.kernel.org, dietmar.eggemann@....com,
        rafael@...nel.org, daniel.lezcano@...aro.org, nm@...com,
        sboyd@...nel.org, mka@...omium.org, dianders@...omium.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [RFC][PATCH 1/2] dt-bindings: power: add Energy Model bindings



On 2/22/22 10:12, Viresh Kumar wrote:
> On 22-02-22, 10:03, Lukasz Luba wrote:
>>
>>
>> On 2/22/22 09:45, Viresh Kumar wrote:
>>> On 22-02-22, 08:06, Lukasz Luba wrote:
>>>> I'm not sure if that would be flexible enough to meet the requirement:
>>>> power for each OPP might be different in one board vs. other board.
>>>
>>> Don't DT files overload values from board files all the time ? Why wouldn't the
>>> same apply for OPP table as well ?
>>
>> In that SoC and family of the boards, there are no such examples.
> 
> Here is one I think.
> 
> arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts
> 
>> It used to be popular in arm32 boards, but I'm not sure nowadays.
> 
> I think it is still common, not with OPPs though.
> 
>>>> AFAIK the OPP definition is more SoC specific.
>>>
>>> This isn't about OPP definition as well, but just that if DT allows you to
>>> override or not. I think it will.
>>>
>>
>> Redefining the whole OPP table, when the freq, voltage, interconnect,
>> and other old entries don't change isn't too messy?
> 
> I think you misunderstood what I said. The common part of the OPP table should
> stay in the central .dtsi file. The dts files though, should just add the power
> specific values to the existing OPP table.
> 

OK, I misunderstood that. If that is possible than it would
be great. I'm assuming you are taking about OPP v2. I can relax the
requirement that I need to provide this DT-EM for arm32, since they
have a legacy OPP v1.

So we might have an entry similar that interconnect for the
bandwidth, but for us it would be 'opp-power-uw'?

Let me have a look about some examples how that could be just
added/extended in the opp table but from board file.
If you have some handy link, I would be grateful.