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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3EAFC7EE29 for ; Wed, 7 Jun 2023 06:42:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236749AbjFGGmO (ORCPT ); Wed, 7 Jun 2023 02:42:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233989AbjFGGmN (ORCPT ); Wed, 7 Jun 2023 02:42:13 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58FCF196; Tue, 6 Jun 2023 23:42:12 -0700 (PDT) Received: from pendragon.ideasonboard.com (om126233170111.36.openmobile.ne.jp [126.233.170.111]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 9B0AF2B6; Wed, 7 Jun 2023 08:41:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1686120104; bh=cH1WjxZXB0Q95UrEgS6nQTqmxFYodH8lXytDlFCSxEU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D9RXxatOayeh6jXiCSpYbaC7LmIXFRv/3LANilIw80P+KNO8TFTYyAcZaZItzJBjh XCe1x8PWt51lldPTI3ePCxGaC774np+KvzIFiB3UFf5l93UCVRbStKGZHaPR02ZcG9 OGD3Z8ZNdbfYOJwVEe+5dZWdz5P9bnnfVJ7KhSms= Date: Wed, 7 Jun 2023 09:42:07 +0300 From: Laurent Pinchart To: Michael Riesch Cc: Mauro Carvalho Chehab , libcamera-devel@lists.libcamera.org, Sakari Ailus , Hans Verkuil , Matthias Fend , Dave Stevenson , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC v2 2/6] media: v4l2-ctrls: clarify documentation of V4L2_CID_FOCUS_RELATIVE Message-ID: <20230607064207.GG14101@pendragon.ideasonboard.com> References: <20230406-feature-controls-lens-v2-0-faa8ad2bc404@wolfvision.net> <20230406-feature-controls-lens-v2-2-faa8ad2bc404@wolfvision.net> <20230606103618.GB25774@pendragon.ideasonboard.com> <46e0aac3-e238-1f32-264c-eed8a849d156@wolfvision.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <46e0aac3-e238-1f32-264c-eed8a849d156@wolfvision.net> Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Michael, On Tue, Jun 06, 2023 at 03:15:33PM +0200, Michael Riesch wrote: > On 6/6/23 12:36, Laurent Pinchart wrote: > > On Tue, Apr 25, 2023 at 11:45:12AM +0200, Michael Riesch wrote: > >> The control V4L2_CID_FOCUS_RELATIVE only makes sense if the device cannot > >> handle absolute focal point positioning with V4L2_CID_FOCUS_ABSOLUTE. > >> Clarify this in the documentation. > >> > >> Signed-off-by: Michael Riesch > >> --- > >> Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst > >> index df29150dce7b..42cf4c3cda0c 100644 > >> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst > >> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst > >> @@ -147,7 +147,9 @@ enum v4l2_exposure_metering - > >> This control moves the focal point of the camera by the specified > >> amount. The unit is undefined. Positive values move the focus closer > >> to the camera, negative values towards infinity. This is a > >> - write-only control. > >> + write-only control. It should be implemented only if the device cannot > >> + handle absolute values. > >> + > > > > Extra blank line. > > Will fix that. > > > I don't think this is right. The control was added for the UVC driver, > > and there are devices that implement both absolute and relative focus. > > I am by no means an expert here and just following Sakari's suggestion > here (see [0]). I can drop the patch, leave it as-is, or modify it. > Whatever makes sense to you guys. But maybe I should leave this to > someone more knowledgeable in this area and drop the patch from my > series. The changes above are completely orthogonal to my work. V4L2_CID_FOCUS_RELATIVE is an annoying control. It was introduced for UVC, and to my surprise, it turns out it has never been implemented in the uvcvideo driver. The 3 devices I know of that implement the UVC relative focus control also implement the UVC absolute focus control. I'm tempted to deprecate this control completely. Sakari, any opinion ? > >> > >> ``V4L2_CID_FOCUS_AUTO (boolean)`` > >> Enables continuous automatic focus adjustments. The effect of manual > >> > > > > [0] https://lore.kernel.org/all/ZDbChgZJHVaaX3%2Fx@kekkonen.localdomain/ -- Regards, Laurent Pinchart