linux-kernel - Re: [PATCH v2 1/2] dt-bindings: Pinefeat cef168 lens control board

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Message-ID: <20250814-intelligent-industrious-cassowary-b73c9b@kuoka>
Date: Thu, 14 Aug 2025 11:04:10 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Aliaksandr Smirnou <support@...efeat.co.uk>
Cc: conor+dt@...nel.org, devicetree@...r.kernel.org, krzk+dt@...nel.org, 
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, mchehab@...nel.org, robh@...nel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: Pinefeat cef168 lens control board

On Tue, Aug 12, 2025 at 08:37:22PM +0100, Aliaksandr Smirnou wrote:
> On Tue, 12 Aug 2025 09:13:22 +0200, Krzysztof Kozlowski wrote:
> > Property says VCC, description says VDD, datasheet says 5V (not 3.3V).
> >
> > I guess this should be for the 5V case, no?
> 
> Thank you following up.
> 
> The 5V line is used exclusively to power the lens motor (through the
> power switch). This 5V supply can come from the Raspberry Pi GPIO
> header, a battery, or other sources. Importantly, this power source
> is independent of the board’s MCU and its kernel driver.

You describe here the entire board, not the MCU only or lens motor
only...

> 
> Additionally, the board does not include any voltage regulators.
> The MCU operates at 3.3V, which is supplied either via the CSI connector
> or the serial connector directly from the Raspberry Pi GPIO 3.3V rail.
> Therefore, the driver does not manage any regulator, which is why the
> “vcc-supply” property was absent in the binding.
> 
> Would you like me to remove the “vcc-supply” property as it was
> originally?

Can the board be used outside of above setup? I understand so far this
is only for Rpi where both above supplies - 3.3 V and 5 V - are coming
from the header pins, so supplies would be totally redundant.

Best regards,
Krzysztof