linux-kernel - Re: [PATCH 1/2] Documentation: dt-bindings: media: i2c: Add ROHM BU64754 bindings

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Message-ID: <6e163f4d-061d-3c20-4c2e-44c74d529f10@linaro.org>
Date:   Sun, 17 Sep 2023 19:27:27 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Kieran Bingham <kieran.bingham@...asonboard.com>,
        linux-media@...r.kernel.org
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] Documentation: dt-bindings: media: i2c: Add ROHM
 BU64754 bindings

On 17/09/2023 12:33, Kieran Bingham wrote:
> Quoting Krzysztof Kozlowski (2023-09-17 10:37:07)
>> On 15/09/2023 18:59, Kieran Bingham wrote:
>>> Add YAML device tree bindings for the ROHM BU64754 VCM Motor Driver for
>>> Camera Autofocus.
>>>
>>> Signed-off-by: Kieran Bingham <kieran.bingham@...asonboard.com>
>>> ---
>>
>> ...
>>
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - enum:
>>> +          - rohm,bu64754
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  vdd-supply:
>>
>> If the supply is not required, how the driver gets any power?
> 
> It may not be controllable. It could be wired to be always on.

That's different. You talk now about board, I am talking about device.
Is the supply required for the device? If yes, then it should be
required by the bindings.

> 
> The device has a low power mode which is controllable by software, so it
> could be always powered on and controlled via software only if desired.
> The driver handles that already as if the regulator isn't specified the
> power down register bits will be set to put it in low power mode.

Best regards,
Krzysztof