linux-kernel - Re: [PATCH] media: i2c: imx219: implement the v4l2 selection api

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Message-ID: <20240116225618.GA4860@pendragon.ideasonboard.com>
Date: Wed, 17 Jan 2024 00:56:18 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Jacopo Mondi <jacopo.mondi@...asonboard.com>,
	Vinay Varma <varmavinaym@...il.com>,
	Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	"open list:SONY IMX219 SENSOR DRIVER" <linux-media@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] media: i2c: imx219: implement the v4l2 selection api

Hello,

On Tue, Jan 16, 2024 at 07:09:59PM +0000, Sakari Ailus wrote:
> On Mon, Jan 08, 2024 at 10:19:35AM +0100, Jacopo Mondi wrote:
> > Hi Sakari, Vinay,
> > 
> >    a more foundamental question is how this usage of the crop/compose
> > API plays with the fact we enumerate only a limited set of frame
> > sizes, and now you can get an arbitrary output size. We could get away
> > by modifying enum_frame_sizes to return a size range (or ranges) but I
> > wonder if it wouldn't be better to introduce an internal pad to
> > represent the pixel array where to apply TGT_CROP in combination with
> > a source pad where we could apply TGT_COMPOSE and an output format.

I'm working on patches that implement an internal image pad, as part of
the work to add embedded data support. I hope to post this in the near
future.

> My earlier review wasn't focussed on the interface at all...
> 
> To depart from the current restrictions on single-subdev sensor drivers,
> this is one option.
> 
> Sensors implement various steps in different orders and different drivers
> have different capabilities, too. Mainly there are two classes: freely
> configurable drivers such cas CCS and then register list based drivers
> where virtually any dependencies between configurations are possible.
> 
> We probably can't support both classes with the same API semantics and due
> to hardware differencies. The sensor UAPI will be less than uniform it has
> been in the past but I don't think this should be an issue.
> 
> I wonder how much common understanding we have at this point on how this
> API would look like. Probably not much?

-- 
Regards,

Laurent Pinchart