linux-kernel - RE: [PATCH v2 2/4] pwm: Add Apple PWM controller

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Message-ID: <OS0PR01MB592217539BCA46FD8F523C2386399@OS0PR01MB5922.jpnprd01.prod.outlook.com>
Date:   Wed, 2 Nov 2022 16:02:35 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Sasha Finkelstein <fnkl.kernel@...il.com>
CC:     "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "marcan@...can.st" <marcan@...can.st>,
        "sven@...npeter.dev" <sven@...npeter.dev>,
        "alyssa@...enzweig.io" <alyssa@...enzweig.io>,
        "asahi@...ts.linux.dev" <asahi@...ts.linux.dev>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 2/4] pwm: Add Apple PWM controller

> Subject: Re: [PATCH v2 2/4] pwm: Add Apple PWM controller
> 
> On Wed, 2 Nov 2022 at 18:33, Biju Das <biju.das.jz@...renesas.com>
> wrote:
> > > +     clk = devm_clk_get_enabled(&pdev->dev, NULL);
> > > +     if (IS_ERR(clk))
> > > +             return PTR_ERR(clk);
> >
> > What is your use case?
> >
> > PWM is configured by bootloader intially??
> >
> > Or
> >
> > PWM is configured by Linux not by the bootloader?
> >
> > Or
> >
> > Driver needs to support both ??
> 
> The PWM device itself is configured by linux, but the clock it uses is
> the systemwide 24 MHz clock, and that is configured by platform
> firmware.

I just asked, because you are unnecessarily turning on the clock or increasing the usage
Count, even if it is not used by anyone during probe.

Cheers,
Biju