linux-kernel - Re: [PATCH 3/5] media: dt-bindings: Add Apple ISP

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Message-ID: <CAMT+MTToVdm72ovNZ8ySySYe5fT99a0Y6bv02NKxADCBCe+pMQ@mail.gmail.com>
Date: Wed, 19 Feb 2025 12:05:29 +0100
From: Sasha Finkelstein <fnkl.kernel@...il.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Krzysztof Kozlowski <krzk@...nel.org>, Sven Peter <sven@...npeter.dev>, 
	Alyssa Rosenzweig <alyssa@...enzweig.io>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Hector Martin <marcan@...can.st>, Ulf Hansson <ulf.hansson@...aro.org>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, asahi@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, 
	linux-media@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH 3/5] media: dt-bindings: Add Apple ISP

On Wed, 19 Feb 2025 at 11:53, Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
> >
> > Those are board-specific and not discoverable via the ISP protocol.
>
> But they are settable through the ISP protocol, aren't they ? For
> instance, looking at isp-imx248.dtsi, the first four entries are
>
>         /* 1280x720 */
>         preset0 {
>                 apple,config-index = <0>;
>                 apple,input-size = <1296 736>;
>                 apple,output-size = <1280 720>;
>                 apple,crop = <8 8 1280 720>;
>         };
>
>         /* 960x720 (4:3) */
>         preset1 {
>                 apple,config-index = <0>;
>                 apple,input-size = <1296 736>;
>                 apple,output-size = <960 720>;
>                 apple,crop = <168 8 960 720>;
>         };
>
>         /* 960x540 (16:9) */
>         preset2 {
>                 apple,config-index = <0>;
>                 apple,input-size = <1296 736>;
>                 apple,output-size = <960 540>;
>                 apple,crop = <8 8 1280 720>;
>         };
>
>         /* 640x480 (4:3) */
>         preset3 {
>                 apple,config-index = <0>;
>                 apple,input-size = <1296 736>;
>                 apple,output-size = <640 480>;
>                 apple,crop = <168 8 960 720>;
>         };
>
> But I may be interested in capturing a 640x480 frame with cropping only
> and without scaling, with
>
> input-size = 1296x736
> output-size = 640x480
> crop = (328,128)/640x480
>
> Or I may want my cropped frame to be located in the upper-left corner:
>
> input-size = 1296x736
> output-size = 640x480
> crop = (8,8)/640x480
>
> If I set those parameters through the ISP protocol, won't it work ?
>
> --
> Regards,
>
> Laurent Pinchart

For cropping - you do not want to change those parameters, the sensor
is partially occluded, and the crop area is specified in such a way
to not expose those pixels. As for scaling - we can expose only the 1:1
scale and let userspace deal with it, but it appears that it expects
the other common output sizes to exist.