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

[Krzysztof Kozlowski]

On 28/08/2023 20:50, Shenwei Wang wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>> Sent: Monday, August 28, 2023 1:42 PM
>> To: Shenwei Wang <shenwei.wang@xxxxxxx>; Ulf Hansson
>> <ulf.hansson@xxxxxxxxxx>
>> Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski
>> <krzysztof.kozlowski+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>;
>> Liam Girdwood <lgirdwood@xxxxxxxxx>; Mark Brown <broonie@xxxxxxxxxx>;
>> imx@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
>> dl-linux-imx <linux-imx@xxxxxxx>
>> 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;
>     };

There is a chip. This is the chip. If you have there only GPIO pin, then
your DTS is just wrong. Drop it. If you learn from wrong DTS, then sure,
power-domain-regulator seems like great idea...

> 
>>> 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?

Just an example. Can be TPS123098.

Best regards,
Krzysztof