Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751588AbaLRQv1 (ORCPT ); Thu, 18 Dec 2014 11:51:27 -0500 Received: from smtp-out-208.synserver.de ([212.40.185.208]:1065 "EHLO smtp-out-208.synserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329AbaLRQvZ (ORCPT ); Thu, 18 Dec 2014 11:51:25 -0500 X-SynServer-TrustedSrc: 1 X-SynServer-AuthUser: lars@metafoo.de X-SynServer-PPID: 20595 Message-ID: <54930604.1020607@metafoo.de> Date: Thu, 18 Dec 2014 17:51:16 +0100 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.3.0 MIME-Version: 1.0 To: "Baluta, Teodora" , "jic23@kernel.org" CC: "linux-kernel@vger.kernel.org" , "linux-iio@vger.kernel.org" , Hans Verkuil , Mauro Carvalho Chehab , linux-media@vger.kernel.org Subject: Re: [RFC PATCH 0/3] Introduce IIO interface for fingerprint sensors References: <1417698017-13835-1-git-send-email-teodora.baluta@intel.com> <5481153B.4070609@kernel.org> <1418047828.18463.10.camel@bebop> In-Reply-To: <1418047828.18463.10.camel@bebop> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Adding V4L folks to Cc for more input. On 12/08/2014 03:10 PM, Baluta, Teodora wrote: > Hello, > > On Vi, 2014-12-05 at 02:15 +0000, Jonathan Cameron wrote: >> On 04/12/14 13:00, Teodora Baluta wrote: >>> This patchset adds support for fingerprint sensors through the IIO interface. >>> This way userspace applications collect information in a uniform way. All >>> processing would be done in the upper layers as suggested in [0]. >>> >>> In order to test out this proposal, a minimal implementation for UPEK's >>> TouchChip Fingerprint Sensor via USB is also available. Although there is an >>> existing implementation in userspace for USB fingerprint devices, including this >>> particular device, the driver represents a proof of concept of how fingerprint >>> sensors could be integrated in the IIO framework regardless of the used bus. For >>> lower power requirements, the SPI bus is preferred and a kernel driver >>> implementation makes more sense. >> >> So why not v4l? These are effectively image sensors.. > > Well, here's why I don't think v4l would be the best option: > > - an image scanner could be implemented in the v4l subsystem, but it > seems far more complicated for a simple fingerprint scanner - it usually > has drivers for webcams, TVs or video streaming devices. The v4l > subsystem (with all its support for colorspace, decoders, image > compression, frame control) seems a bit of an overkill for a very > straightforward fingerprint imaging sensor. > > - a fingerprint device could also send out a processed information, not > just the image of a fingerprint. This means that the processing is done > in hardware - the UPEK TouchStrip chipset in libfprint has this behavior > (see [0]). So, the IIO framework would support a uniform way of handling > fingerprint devices that either do processing in software or in > hardware. > > The way I see it now, for processed fingerprint information, an IIO > device could have an IIO_FINGERPRINT channel with a modifier and only > the sensitivity threshold attribute set. We would also need two > triggers: one for enrollment and one for the verification mode to > control the device from a userspace application. > > Thanks, > Teodora > > [0] http://www.freedesktop.org/wiki/Software/fprint/libfprint/upekts/ > > >>> >>> A sysfs trigger is enabled and the device starts scanning. As soon as an image >>> is available it is written in the character device /dev/iio:deviceX. >>> >>> Userspace applications will be able to calculate the expected image size using >>> the fingerprint attributes height, width and bit depth. Other attributes >>> introduced for the fingerprint channel in IIO represent information that aids in >>> the fingerprint image processing. Besides these, the proposed interface offers >>> userspace a way to read a feedback after a scan (like the swipe was too slow or >>> too fast) through a modified fingerprint_status channel. >>> >>> [0] http://www.spinics.net/lists/linux-iio/msg11463.html >>> >>> Teodora Baluta (3): >>> iio: core: add support for fingerprint devices >>> iio: core: change channel's storagebits/realbits to u32 >>> iio: fingerprint: add fingerprint sensor via USB >>> >>> Documentation/ABI/testing/sysfs-bus-iio | 51 +++ >>> drivers/iio/Kconfig | 1 + >>> drivers/iio/Makefile | 1 + >>> drivers/iio/fingerprint/Kconfig | 15 + >>> drivers/iio/fingerprint/Makefile | 5 + >>> drivers/iio/fingerprint/fp_tc.c | 162 +++++++++ >>> drivers/iio/fingerprint/fp_tc.h | 22 ++ >>> drivers/iio/fingerprint/fp_tc_usb.c | 618 ++++++++++++++++++++++++++++++++ >>> drivers/iio/fingerprint/fp_tc_usb.h | 144 ++++++++ >>> drivers/iio/industrialio-core.c | 9 + >>> include/linux/iio/iio.h | 11 +- >>> include/linux/iio/types.h | 10 + >>> 12 files changed, 1047 insertions(+), 2 deletions(-) >>> create mode 100644 drivers/iio/fingerprint/Kconfig >>> create mode 100644 drivers/iio/fingerprint/Makefile >>> create mode 100644 drivers/iio/fingerprint/fp_tc.c >>> create mode 100644 drivers/iio/fingerprint/fp_tc.h >>> create mode 100644 drivers/iio/fingerprint/fp_tc_usb.c >>> create mode 100644 drivers/iio/fingerprint/fp_tc_usb.h >>> >> > > N�����r��y���b�X��ǧv�^�)޺{.n�+����{��*"��^n�r���z���h����&���G���h�(�階�ݢj"���m�����z�ޖ���f���h���~�mml== > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/