Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751812AbdCQMUO (ORCPT ); Fri, 17 Mar 2017 08:20:14 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:40640 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751402AbdCQMUL (ORCPT ); Fri, 17 Mar 2017 08:20:11 -0400 Date: Fri, 17 Mar 2017 12:16:08 +0000 From: Russell King - ARM Linux To: Philipp Zabel Cc: Hans Verkuil , Mauro Carvalho Chehab , Sakari Ailus , Steve Longerbeam , robh+dt@kernel.org, mark.rutland@arm.com, shawnguo@kernel.org, kernel@pengutronix.de, fabio.estevam@nxp.com, mchehab@kernel.org, nick@shmanahar.org, markus.heiser@darmarIT.de, laurent.pinchart+renesas@ideasonboard.com, bparrot@ti.com, geert@linux-m68k.org, arnd@arndb.de, sudipm.mukherjee@gmail.com, minghsiu.tsai@mediatek.com, tiffany.lin@mediatek.com, jean-christophe.trotin@st.com, horms+renesas@verge.net.au, niklas.soderlund+renesas@ragnatech.se, robert.jarzmik@free.fr, songjun.wu@microchip.com, andrew-ct.chen@mediatek.com, gregkh@linuxfoundation.org, shuah@kernel.org, sakari.ailus@linux.intel.com, pavel@ucw.cz, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, devel@driverdev.osuosl.org, Steve Longerbeam , Jacek Anaszewski Subject: Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline Message-ID: <20170317121608.GE21222@n2100.armlinux.org.uk> References: <20170310140124.GV21222@n2100.armlinux.org.uk> <20170310125342.7f047acf@vento.lan> <20170310223714.GI3220@valkosipuli.retiisi.org.uk> <20170311082549.576531d0@vento.lan> <20170313124621.GA10701@valkosipuli.retiisi.org.uk> <20170314004533.3b3cd44b@vento.lan> <20170317114203.GZ21222@n2100.armlinux.org.uk> <1489752127.2905.49.camel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1489752127.2905.49.camel@pengutronix.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1341 Lines: 29 On Fri, Mar 17, 2017 at 01:02:07PM +0100, Philipp Zabel wrote: > I think most of the simple, fixed pipeline use cases could be handled by > libv4l2, by allowing to pass a v4l2 subdevice path to v4l2_open. If that > function internally would set up the media links to the > nearest /dev/video interface, propagate format, resolution and frame > intervals if necessary, and return an fd to the video device, there'd be > no additional complexity for the users beyond selecting the v4l2_subdev > instead of the video device. ... which would then require gstreamer to be modified too. The gstreamer v4l2 plugin looks for /dev/video* or /dev/v4l2/video* devices and monitors these for changes, so gstreamer applications know which capture devices are available: const gchar *paths[] = { "/dev", "/dev/v4l2", NULL }; const gchar *names[] = { "video", NULL }; /* Add some depedency, so the dynamic features get updated upon changes in * /dev/video* */ gst_plugin_add_dependency (plugin, NULL, paths, names, GST_PLUGIN_DEPENDENCY_FLAG_FILE_NAME_IS_PREFIX); I haven't checked yet whether sys/v4l2/gstv4l2deviceprovider.c knows anything about the v4l2 subdevs. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.