Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935126AbdCLSOX (ORCPT ); Sun, 12 Mar 2017 14:14:23 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:45222 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934142AbdCLSOR (ORCPT ); Sun, 12 Mar 2017 14:14:17 -0400 Date: Sun, 12 Mar 2017 19:14:10 +0100 From: Pavel Machek To: Russell King - ARM Linux Cc: Steve Longerbeam , mark.rutland@arm.com, andrew-ct.chen@mediatek.com, minghsiu.tsai@mediatek.com, nick@shmanahar.org, songjun.wu@microchip.com, Hans Verkuil , shuah@kernel.org, devel@driverdev.osuosl.org, markus.heiser@darmarIT.de, laurent.pinchart+renesas@ideasonboard.com, robert.jarzmik@free.fr, Mauro Carvalho Chehab , geert@linux-m68k.org, p.zabel@pengutronix.de, linux-media@vger.kernel.org, devicetree@vger.kernel.org, kernel@pengutronix.de, arnd@arndb.de, tiffany.lin@mediatek.com, bparrot@ti.com, robh+dt@kernel.org, horms+renesas@verge.net.au, mchehab@kernel.org, linux-arm-kernel@lists.infradead.org, niklas.soderlund+renesas@ragnatech.se, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Sakari Ailus , jean-christophe.trotin@st.com, sakari.ailus@linux.intel.com, fabio.estevam@nxp.com, shawnguo@kernel.org, sudipm.mukherjee@gmail.com Subject: Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit controls from a pipeline Message-ID: <20170312181410.GA3124@amd> References: <20170310120902.1daebc7b@vento.lan> <5e1183f4-774f-413a-628a-96e0df321faf@xs4all.nl> <20170311101408.272a9187@vento.lan> <20170311153229.yrdjmggb3p2suhdw@ihha.localdomain> <20170311184551.GD21222@n2100.armlinux.org.uk> <1f1b350a-5523-34bc-07b7-f3cd2d1fd4c1@gmail.com> <20170311185959.GF21222@n2100.armlinux.org.uk> <4917d7fb-2f48-17cd-aa2f-d54b0f19ed6e@gmail.com> <20170312073745.GI21222@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ew6BAiZeqk4r7MaW" Content-Disposition: inline In-Reply-To: <20170312073745.GI21222@n2100.armlinux.org.uk> 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: 3752 Lines: 91 --ew6BAiZeqk4r7MaW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun 2017-03-12 07:37:45, Russell King - ARM Linux wrote: > On Sat, Mar 11, 2017 at 07:31:18PM -0800, Steve Longerbeam wrote: > >=20 > >=20 > > On 03/11/2017 10:59 AM, Russell King - ARM Linux wrote: > > >On Sat, Mar 11, 2017 at 10:54:55AM -0800, Steve Longerbeam wrote: > > >> > > >> > > >>On 03/11/2017 10:45 AM, Russell King - ARM Linux wrote: > > >>>I really don't think expecting the user to understand and configure > > >>>the pipeline is a sane way forward. Think about it - should the > > >>>user need to know that, because they have a bayer-only CSI data > > >>>source, that there is only one path possible, and if they try to > > >>>configure a different path, then things will just error out? > > >>> > > >>>For the case of imx219 connected to iMX6, it really is as simple as > > >>>"there is only one possible path" and all the complexity of the media > > >>>interfaces/subdevs is completely unnecessary. Every other block in > > >>>the graph is just noise. > > >>> > > >>>The fact is that these dot graphs show a complex picture, but reality > > >>>is somewhat different - there's only relatively few paths available > > >>>depending on the connected source and the rest of the paths are > > >>>completely useless. > > >>> > > >> > > >>I totally disagree there. Raw bayer requires passthrough yes, but for > > >>all other media bus formats on a mipi csi-2 bus, and all other media > > >>bus formats on 8-bit parallel buses, the conersion pipelines can be > > >>used for scaling, CSC, rotation, and motion-compensated de-interlacin= g. > > > > > >... which only makes sense _if_ your source can produce those formats. > > >We don't actually disagree on that. > >=20 > > ...and there are lots of those sources! You should try getting out of > > your imx219 shell some time, and have a look around! :) >=20 > If you think that, you are insulting me. I've been thinking about this > from the "big picture" point of view. If you think I'm only thinking > about this from only the bayer point of view, you're wrong. Can you stop that insults nonsense? > Given what Mauro has said, I'm convinced that the media controller stuff > is a complete failure for usability, and adding further drivers using it > is a mistake. Hmm. But you did not present any alternative. Seems some hardware is simply complex. So either we don't add complex drivers (_that_ would be a mistake), or some userspace solution will need to be done. Shell-script running media-ctl does not seem that hard. > So, tell me how the user can possibly use iMX6 video capture without > resorting to opening up a terminal and using media-ctl to manually > configure the pipeline. How is the user going to control the source > device without using media-ctl to find the subdev node, and then using > v4l2-ctl on it. How is the user supposed to know which /dev/video* > node they should be opening with their capture application? Complex hardware sometimes requires userspace configuration. Running a shell script on startup does not seem that hard. And maybe we could do some kind of default setup in kernel, but that does not really solve the problem. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --ew6BAiZeqk4r7MaW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAljFj/IACgkQMOfwapXb+vK0qQCgt0pDtFBEZJ0gKHL0QjVyv72R rOQAnjiBH+6uNfIC5dUXkyfT5tRi0t91 =Hoir -----END PGP SIGNATURE----- --ew6BAiZeqk4r7MaW--