linux-kernel - Re: [PATCH 1/2] dt-bindings: power: Add regulator-pd yaml file

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Message-ID: <PAXPR04MB91852AD4E5242306B57A910B89E0A@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date:   Mon, 28 Aug 2023 18:50:23 +0000
From:   Shenwei Wang <shenwei.wang@....com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
CC:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH 1/2] dt-bindings: power: Add regulator-pd yaml file



> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Sent: Monday, August 28, 2023 1:42 PM
> To: Shenwei Wang <shenwei.wang@....com>; Ulf Hansson
> <ulf.hansson@...aro.org>
> Cc: Rob Herring <robh+dt@...nel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@...aro.org>; Conor Dooley <conor+dt@...nel.org>;
> Liam Girdwood <lgirdwood@...il.com>; Mark Brown <broonie@...nel.org>;
> imx@...ts.linux.dev; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org;
> dl-linux-imx <linux-imx@....com>
> Subject: [EXT] Re: [PATCH 1/2] dt-bindings: power: Add regulator-pd yaml file
> >>>>> Are you suggesting to move the regulator-pd to the imx directory
> >>>>> and add a company prefix to the compatible string?
> >>>>
> >>>> There is no such part of iMX processor as such
> >>>> regulator-power-domain, so I don't recommend that approach. DTS
> >>>> nodes represent hardware, not your SW layers.
> >>>>
> >>>
> >>> That's not always the case, as we do sometimes need a virtual device.
> >>> As an example, the "regulator-fixed" acts as a software abstraction
> >>> layer to create virtual regulator devices by interfacing with the
> >>> underlying
> >> GPIO drivers.
> >>
> >> Not true. This is a real regulator device. Real hardware on the board.
> >> You can even see and touch it.
> >>
> >
> > The physical hardware component is the GPIO pin, which is what you can only
> touch.
> 
> No. The regulator is the chip.
> 

In the definition of dts node below, where is the chip? The real hardware is just a GPIO Pin.
    reg1: regulator-1 {
    	compatible = "regulator-fixed";
    	regulator-name = "REG1";
    	regulator-min-microvolt = <3000000>;
    	regulator-max-microvolt = <3000000>;
    	gpio = <&lsio_gpio4 19 GPIO_ACTIVE_HIGH>;
    	enable-active-high;
    };

> > The regulator functions virtually through software layer above of the
> > GPIO driver. While we may call it a "regulator" or whatever else, this
> > cannot obscure the fact that the underlying hardware is just a GPIO pin being
> used in a specialized way.
> 
> The regulator is some tiny little box, you can touch and called
> ti,tps51632 or similar.
> 

We are talking about the specific "regulator-fixed" driver, why did you bring up "ti,tps51632" here?

Thanks,
Shenwei

> 
> 
> Best regards,
> Krzysztof