From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:54200 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297AbdBOIJN (ORCPT ); Wed, 15 Feb 2017 03:09:13 -0500 Date: Wed, 15 Feb 2017 09:09:09 +0100 From: Pavel Machek To: Sakari Ailus Cc: linux-media@vger.kernel.org Subject: Re: [PATCH v3 1/2] v4l: Add camera voice coil lens control class, current control Message-ID: <20170215080909.GA3693@amd> References: <1487074823-28274-1-git-send-email-sakari.ailus@linux.intel.com> <1487074823-28274-2-git-send-email-sakari.ailus@linux.intel.com> <20170214224750.GE11317@amd> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="wac7ysb48OaltWcw" Content-Disposition: inline In-Reply-To: Sender: linux-media-owner@vger.kernel.org List-ID: --wac7ysb48OaltWcw Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > On 02/15/17 00:47, Pavel Machek wrote: > > On Tue 2017-02-14 14:20:22, Sakari Ailus wrote: > >> Add a V4L2 control class for voice coil lens driver devices. These are > >> simple devices that are used to move a camera lens from its resting > >> position. > >> > >> Signed-off-by: Sakari Ailus > >=20 > > Looks good to me. > >=20 > > I wonder... should we somehow expose the range of diopters to > > userspace? I believe userland camera application will need that > > information. >=20 > It'd certainly be useful to be able to provide more information. >=20 > The question is: where to store it, and how? It depends on the voice > coil, the spring constant, the lens and the distance of the lens from > the sensor --- at least. Probably the sensor size as well. >=20 > On voice coil lenses it is also somewhat inexact. I was thinking read-only attribute providing minimum and maximum diopters in case there's linear relationship as on N900. +#define V4L2_CID_VOICE_DIOPTERS_AT_REST (V4L2_CID_VOICE_COIL_CLASS_BASE + = 2) +#define V4L2_CID_VOICE_DIOPTERS_AT_MAX (V4L2_CID_VOICE_COIL_CLASS_BASE + 3) ? Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --wac7ysb48OaltWcw Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlikDKUACgkQMOfwapXb+vKFdQCfSC8YRxOmZBBmX6TvpvFVwO9Z d2oAn1EBIcUHXKp7FdpJi03tJnBp7v0R =aoZh -----END PGP SIGNATURE----- --wac7ysb48OaltWcw--