linux-kernel - Re: [PATCH v4 2/2] arm64: dts: sc7180: Add required-opps for i2c

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Date:   Fri, 16 Jul 2021 22:21:06 +0200
From:   Stephen Boyd <swboyd@...omium.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>
Cc:     ulf.hansson@...aro.org, viresh.kumar@...aro.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        rojay@...eaurora.org, stephan@...hold.net
Subject: Re: [PATCH v4 2/2] arm64: dts: sc7180: Add required-opps for i2c

Quoting Bjorn Andersson (2021-07-16 13:18:56)
> On Fri 16 Jul 05:00 CDT 2021, Rajendra Nayak wrote:
>
> > qup-i2c devices on sc7180 are clocked with a fixed clock (19.2 MHz)
> > Though qup-i2c does not support DVFS, it still needs to vote for a
> > performance state on 'CX' to satisfy the 19.2 Mhz clock frequency
> > requirement.
> >
>
> Sounds good, but...
>
> > Use 'required-opps' to pass this information from
> > device tree, and also add the power-domains property to specify
> > the CX power-domain.
> >
>
> ..is the required-opps really needed with my rpmhpd patch in place?
>

Yes? Because rpmhpd_opp_low_svs is not the lowest performance state for
CX.