linux-kernel - Re: [PATCH] arm64: dts: qcom: sc8280xp: Flush RSC sleep & wake votes

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Message-ID: <ZGIdkHn6bVbln5uy@hovoldconsulting.com>
Date:   Mon, 15 May 2023 13:54:56 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Bjorn Andersson <quic_bjorande@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sc8280xp: Flush RSC sleep & wake votes

On Sun, May 14, 2023 at 07:38:28PM -0700, Bjorn Andersson wrote:
> On Sat, May 13, 2023 at 11:09:07AM +0200, Konrad Dybcio wrote:
> > 
> > 
> > On 12.05.2023 17:04, Bjorn Andersson wrote:
> > > The rpmh driver will cache sleep and wake votes until the cluster
> > > power-domain is about to enter idle, to avoid unnecessary writes. So
> > > associate the apps_rsc with the cluster pd, so that it can be notified
> > > about this event.
> > > 
> > > Without this, only AMC votes are being commited.
> > Ouch.
> > 
> > Should we make this required: in bindings and add it to all
> > platforms?
> > 
> 
> I though this was an optimization and in the absence of this callback
> the driver would just write out wake and sleep sets as well. But per the
> current implementation (and perhaps some underlying cause?) it is indeed
> required, if you care about power consumption.
> 
> > > 
> > > Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
> > > ---
> > Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> > Fixes: 152d1faf1e2f ("arm64: dts: qcom: add SC8280XP platform")
> > 
> 
> The Fixes sounds reasonable.

Note that support for the cluster domain was not added until 6.2 and
commit 25092e6100ac ("soc: qcom: rpmh-rsc: Attach RSC to cluster PM
domain") while support for sc8280xp went into 5.19 IIRC.

Johan