linux-kernel - Re: [RFC PATCH 0/4] cpufreq: qcom-hw: Move clocks to CPU node

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Message-ID: <20220801054255.GA12039@thinkpad>
Date:   Mon, 1 Aug 2022 11:12:55 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Manivannan Sadhasivam <mani@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Johan Hovold <johan@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [RFC PATCH 0/4] cpufreq: qcom-hw: Move clocks to CPU node

On Mon, Aug 01, 2022 at 08:07:56AM +0530, Viresh Kumar wrote:
> On 18-07-22, 07:27, Viresh Kumar wrote:
> > The OPP tables, which are part of the CPU nodes, mentions clock rates.
> > Are these values for the cxo/gpll clocks or the clock that reaches the
> > CPUs? I believe the latter. The DT is not really complete if the CPU
> > node mentions the frequency, but not the source clock. It works for
> > you because you don't want to do clk_set_rate() in this case, but then
> > it leaves other frameworks, like OPP, confused and rightly so.
> > 
> > Normally, there is always a difference in what the OPP table contains
> > as frequency value and what the hardware programs, mostly it is small
> > though. It shouldn't prevent us from having the hierarchy clearly
> > defined in the DT.
> > 
> > Based on your description, I think it would be better to make
> > cpufreq-hw a clock provider and CPUs the consumer of it. It would then
> > allow the OPP core to not carry the hack to make it all work.
> 
> Bjorn / Mani,
> 
> Can we please get this sorted out ? I don't want to carry an unnecessary hack in
> the OPP core for this.
> 

I'm waiting for inputs from Bjorn.

@Bjorn: What do you think of the proposal to add qcom-cpufreq-hw as the clk
provider for CPUs?

Thanks,
Mani

> -- 
> viresh

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