From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756114AbbAZKYx (ORCPT ); Mon, 26 Jan 2015 05:24:53 -0500 Received: from mga03.intel.com ([134.134.136.65]:59311 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754201AbbAZKYt (ORCPT ); Mon, 26 Jan 2015 05:24:49 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,468,1418112000"; d="scan'208";a="667545371" From: "Baluta, Teodora" To: "floe@butterbrot.org" CC: "s.nawrocki@samsung.com" , "lars@metafoo.de" , "linux-kernel@vger.kernel.org" , "jic23@kernel.org" , "linux-media@vger.kernel.org" , "m.chehab@samsung.com" , "linux-iio@vger.kernel.org" , "hverkuil@xs4all.nl" Subject: Re: [RFC PATCH 0/3] Introduce IIO interface for fingerprint sensors Thread-Topic: [RFC PATCH 0/3] Introduce IIO interface for fingerprint sensors Thread-Index: AQHQD8JdQ+QdbPbvv0iTNHDhYqBWSZyAQyGAgAV+ygCAD+Q9AIAMNCWAgB5BKgCAAZkAAIAMMOIggABTZgCABExTgA== Date: Mon, 26 Jan 2015 10:24:44 +0000 Message-ID: <1422267881.2662.39.camel@bebop> References: <1417698017-13835-1-git-send-email-teodora.baluta@intel.com> <5481153B.4070609@kernel.org> <1418047828.18463.10.camel@bebop> <54930604.1020607@metafoo.de> <549D42BD.1050901@kernel.org> <1421255642.31900.4.camel@bebop> <54B7FAF2.8080207@samsung.com> <54C27AE4.4020702@butterbrot.org> In-Reply-To: <54C27AE4.4020702@butterbrot.org> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.237.104.145] Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id t0QAOwCx016207 Hi Florian, Thanks for the reply! On Vi, 2015-01-23 at 17:46 +0100, Florian Echtler wrote: > Hello Teodora, > > On 23.01.2015 14:05, Baluta, Teodora wrote: > > The fingerprint sensor acts more like a scanner device, so the > > closest type is the V4L2_CAP_VIDEO_CAPTURE. However, this is not a > > perfect match because the driver only sends an image, once, when > > triggered. Would it be a better alternative to define a new > > capability type? Or it would be acceptable to simply have a video > > device with no frame buffer or frame rate and the user space > > application to read from the character device /dev/videoX? > Sorry if I jump in here right in the middle of this discussion, but some > time ago, I wrote a fingerprint sensor driver for the Siemens ID Mouse > (still part of the kernel AFAICT) which acts as a misc device and just > creates a character device node that can be used to directly read a PGM > file. I agree that it would be the simplest approach if you want a USB fingerprint driver in kernel space, but I was looking for a way to support fingerprint devices regardless of bus (there's also fingerprint devices that use SPI) and provide a common interface for user space applications. The actual driver for UPEK's TouchChip sensor is just a proof of concept on how the interface would work, rather than the final goal. There's already a library that enables USB-only fingerprint devices (libfprint). > > Maybe this would be a slightly simpler approach than pulling in all the > streaming-optimized features of V4L2? I agree that for a fingerprint device, the V4L2 subsystem offers too much (the initial RFC is for IIO). Thanks, Teodora {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I