From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDFCEC433E0 for ; Mon, 10 Aug 2020 07:24:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CE492073A for ; Mon, 10 Aug 2020 07:24:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725984AbgHJHYi (ORCPT ); Mon, 10 Aug 2020 03:24:38 -0400 Received: from relay2-d.mail.gandi.net ([217.70.183.194]:52997 "EHLO relay2-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725911AbgHJHYh (ORCPT ); Mon, 10 Aug 2020 03:24:37 -0400 X-Originating-IP: 82.52.18.94 Received: from uno.localdomain (host-82-52-18-94.retail.telecomitalia.it [82.52.18.94]) (Authenticated sender: jacopo@jmondi.org) by relay2-d.mail.gandi.net (Postfix) with ESMTPSA id C0BC640008; Mon, 10 Aug 2020 07:24:32 +0000 (UTC) Date: Mon, 10 Aug 2020 09:28:14 +0200 From: Jacopo Mondi To: Laurent Pinchart Cc: Hans Verkuil , Sakari Ailus , Linux Media Mailing List , Sowjanya Komatineni , Ricardo Ribalda Delgado , libcamera-devel@lists.libcamera.org Subject: Re: your mail Message-ID: <20200810072814.vwr4ba5uv3ps7dfj@uno.localdomain> References: <20200805105721.15445-1-jacopo@jmondi.org> <20200809155311.GB5981@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200809155311.GB5981@pendragon.ideasonboard.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Laurent, On Sun, Aug 09, 2020 at 06:53:11PM +0300, Laurent Pinchart wrote: > Hi Jacopo, > > On Wed, Aug 05, 2020 at 12:57:17PM +0200, Jacopo Mondi wrote: > > Subject: [PATCH 0/4] media: docs: Document pixel array properties > > > > Hans' patch "[PATCH] imx219: selection compliance fixes" sparkled a discussion > > on how the V4L2 selection targets have to be used in order to access an > > image sensor pixel array properties. > > > > The discussion shown how much under-specified that part was, so this is > > an attempt to provide a bit documentation for this. > > > > My feeling is that we're hijacking the existing targets for this use case > > and we should probably define new ones, considering how few users we have in > > mainline of them at the moment. > > Do you mean you think we should create new targets instead of reusing > the existing ones as you do in this series ? I don't see anything really > wrong in reusing the existing targets, provided we document them > properly, and it's not too much of a hack (that is, the documented > purpose reasonably matches the target name), but maybe I'm missing the > issue. Yes, that's what I meant. To me, if you have something and you need to document it with "if applied to X it means Y, if applied to Z it means W etcetc" feels like we're abusing it. Having sensor's specific targets would make clear what a target represents without the ambiguities of defining the symbol semantic depending on the device it applies to (which means userspace would need to know what kind of device it's dealing with precisely). That said, my preference would be using a different API, but see my reply to your other email for that. Thanks j > > > On top Hans' patch with reworded commit message and minor updates. > > > > For reference, we're using the V4L2 selection targets in libcamera to retrieve > > the sensor pixel array properties to be reported to applications for > > calibration purposes. The currently defined pixel properties for libcamera > > are available here: > > https://git.linuxtv.org/libcamera.git/tree/src/libcamera/property_ids.yaml#n390 > > > > Thanks > > j > > > > Hans Verkuil (1): > > media: i2c: imx219: Selection compliance fixes > > > > Jacopo Mondi (3): > > media: docs: Describe pixel array properties > > media: docs: Describe targets for sensor properties > > media: docs: USe SUBDEV_G_SELECTION for sensor properties > > > > .../userspace-api/media/v4l/dev-subdev.rst | 85 +++++++++++++++++++ > > .../media/v4l/v4l2-selection-targets.rst | 49 +++++++++++ > > .../media/v4l/vidioc-subdev-g-selection.rst | 4 + > > drivers/media/i2c/imx219.c | 17 ++-- > > 4 files changed, 147 insertions(+), 8 deletions(-) > > -- > Regards, > > Laurent Pinchart