linux-kernel - Re: [PATCH 3/3] arm64: dts: qcom: pm8350c: Add pwm support

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Message-ID: <YTjW9LAGhTuszoa4@google.com>
Date:   Wed, 8 Sep 2021 08:29:56 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     skakit@...eaurora.org
Cc:     Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        swboyd@...omium.org, kgunda@...eaurora.org,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 3/3] arm64: dts: qcom: pm8350c: Add pwm support

On Wed, Sep 08, 2021 at 02:37:39PM +0530, skakit@...eaurora.org wrote:
> On 2021-09-07 23:46, Matthias Kaehlcke wrote:
> > On Mon, Sep 06, 2021 at 04:11:07PM +0530, satya priya wrote:
> > > Add pwm support for PM8350C pmic.
> > > 
> > > Signed-off-by: satya priya <skakit@...eaurora.org>
> > > ---
> > >  arch/arm64/boot/dts/qcom/pm8350c.dtsi | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/arch/arm64/boot/dts/qcom/pm8350c.dtsi
> > > b/arch/arm64/boot/dts/qcom/pm8350c.dtsi
> > > index e1b75ae..ecdae55 100644
> > > --- a/arch/arm64/boot/dts/qcom/pm8350c.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/pm8350c.dtsi
> > > @@ -29,6 +29,12 @@
> > >  			interrupt-controller;
> > >  			#interrupt-cells = <2>;
> > >  		};
> > > +
> > > +		pm8350c_pwm4: pwm {
> > 
> > What does the '4' represent, an internal channel number? It should
> > probably be omitted if the PM8350 only has a single output PWM
> > port.
> > 
> 
> pm8350c has four PWMs, but I think we can drop the '4' here.

Why is only one PWM exposed if the PMIC has for of them? Why number 4
and not one of the others?