linux-kernel - Re: [PATCH] arm64: dts: qcom: sc7280: Add PMIC peripherals for SC7280

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Message-ID: <YFjVEjcx36J97hVW@google.com>
Date:   Mon, 22 Mar 2021 10:34:10 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     skakit@...eaurora.org
Cc:     Rob Herring <robh+dt@...nel.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, kgunda@...eaurora.org
Subject: Re: [PATCH] arm64: dts: qcom: sc7280: Add PMIC peripherals for SC7280

Hi Satya,

On Mon, Mar 22, 2021 at 06:50:47PM +0530, skakit@...eaurora.org wrote:
> Hi Matthias,
> 
> On 2021-03-13 02:10, Matthias Kaehlcke wrote:
> > Hi Satya,
> > 
> > On Thu, Mar 11, 2021 at 04:10:29PM +0530, satya priya wrote:
> > > Add PM7325/PM8350C/PMK8350/PMR735A peripherals such as PON,
> > > GPIOs, RTC and other PMIC infra modules for SC7280.
> > > 
> > > Signed-off-by: satya priya <skakit@...eaurora.org>
> > > ---
> > > This patch depends on base DT and board files for SC7280 to merge
> > > first
> > > https://lore.kernel.org/patchwork/project/lkml/list/?series=487403
> > > 
> > >  arch/arm64/boot/dts/qcom/pm7325.dtsi  |  60 ++++++++++++++++++++
> > >  arch/arm64/boot/dts/qcom/pm8350c.dtsi |  60 ++++++++++++++++++++
> > >  arch/arm64/boot/dts/qcom/pmk8350.dtsi | 104
> > > ++++++++++++++++++++++++++++++++++
> > >  arch/arm64/boot/dts/qcom/pmr735a.dtsi |  60 ++++++++++++++++++++
> > >  arch/arm64/boot/dts/qcom/sc7280.dtsi  |   8 +++
> > >  5 files changed, 292 insertions(+)
> > >  create mode 100644 arch/arm64/boot/dts/qcom/pm7325.dtsi
> > >  create mode 100644 arch/arm64/boot/dts/qcom/pm8350c.dtsi
> > >  create mode 100644 arch/arm64/boot/dts/qcom/pmk8350.dtsi
> > >  create mode 100644 arch/arm64/boot/dts/qcom/pmr735a.dtsi
> > > 
> > > diff --git a/arch/arm64/boot/dts/qcom/pm7325.dtsi
> > > b/arch/arm64/boot/dts/qcom/pm7325.dtsi
> > > new file mode 100644
> > > index 0000000..393b256
> > > --- /dev/null
> > > +++ b/arch/arm64/boot/dts/qcom/pm7325.dtsi
> > > @@ -0,0 +1,60 @@
> > 
> > ...
> > 
> > > +		polling-delay-passive = <100>;
> > > +		polling-delay = <0>;
> > 
> > Are you sure that no polling delay is needed? How does the thermal
> > framework
> > detect that the temperatures is >= the passive trip point and that it
> > should
> > start polling at 'polling-delay-passive' rate?
> > 
> 
> As the temp-alarm has interrupt support, whenever preconfigured threshold
> violates it notifies thermal framework, so I think the polling delay is not
> needed here.

>From the documentation I found it's not clear to me how exactly these
interrupts work. Is a single interrupt triggered when the threshold is
violated or are there periodic (?) interrupts as long as the temperature
is above the stage 0 threshold?

Why is 'polling-delay-passive' passive needed if there are interrupts? Maybe
to detect that the zone should transition from passive to no cooling when the
temperature drops below the stage 0 threshold?