linux-kernel - Re: [PATCH v5 21/25] dt-bindings: media: imx258: Add binding for powerdown-gpio

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Date: Mon, 20 May 2024 13:19:40 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Ondřej Jirman <megi@....cz>, git@...gi311.com,
	linux-media@...r.kernel.org, dave.stevenson@...pberrypi.com,
	jacopo.mondi@...asonboard.com, mchehab@...nel.org, robh@...nel.org,
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
	shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
	festevam@...il.com, devicetree@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	pavel@....cz, phone-devel@...r.kernel.org,
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH v5 21/25] dt-bindings: media: imx258: Add binding for
 powerdown-gpio

Hi Ondřej,

On Mon, May 20, 2024 at 02:55:26PM +0200, Ondřej Jirman wrote:
> On Fri, May 17, 2024 at 08:31:35AM GMT, Sakari Ailus wrote:
> > Hi Luis,
> > 
> > On Wed, May 01, 2024 at 09:24:38AM -0600, git@...gi311.com wrote:
> > > From: Ondrej Jirman <megi@....cz>
> > > 
> > > Add powerdown-gpio binding as it is required for some boards.
> > 
> > I thought the conclusion was that this wasn't a property of the sensor? If
> > it needs to be controlled, then this should take place somewhere else than
> > in the sensor driver.
> 
> It's a property of the sensor modules. It's just optional on
> some, eg. (pin 8):
> 
>   https://assets-global.website-files.com/63b65bd4974577341e1fe194/654290d4d0fb173e87f754ed_IMX_258_FF_drawing.png
> 
> Where else should it be so that the module is described properly in the 
> DT and the powerdown signal can be used as part of powerup/down sequence
> of the sensor?

That's an interesting case. The document does suggest the PWDN pin isn't
connected though.

Is this pin used for something? If so, what is it? The sensor doesn't have
it and generally the module in this respect just contains wiring.

Someone earlier suggested this could have been related to the VCM.

-- 
Regards,

Sakari Ailus