Message-ID: <1489758670.2905.52.camel@pengutronix.de>
Subject: Re: [PATCH v4 14/36] [media] v4l2-mc: add a function to inherit
 controls from a pipeline
From: Philipp Zabel <p.zabel@pengutronix.de>
To: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>,
        Russell King - ARM Linux <linux@armlinux.org.uk>,
        Hans Verkuil <hverkuil@xs4all.nl>, Sakari Ailus <sakari.ailus@iki.fi>,
        Steve Longerbeam <slongerbeam@gmail.com>, 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, 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 <steve_longerbeam@mentor.com>,
        Jacek Anaszewski <j.anaszewski@samsung.com>
Date: Fri, 17 Mar 2017 14:51:10 +0100
In-Reply-To: <20170317102410.18c966ae@vento.lan>
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On Fri, 2017-03-17 at 10:24 -0300, Mauro Carvalho Chehab wrote:
[...]
> The big question, waiting for an answer on the last 8 years is
> who would do that? Such person would need to have several different
> hardware from different vendors, in order to ensure that it has
> a generic solution.
> 
> It is a way more feasible that the Kernel developers that already 
> have a certain hardware on their hands to add support inside the
> driver to forward the controls through the pipeline and to setup
> a "default" pipeline that would cover the common use cases at
> driver's probe.

Actually, would setting pipeline via libv4l2 plugin and letting drivers
provide a sane enabled default pipeline configuration be mutually
exclusive? Not sure about the control forwarding, but at least a simple
link setup and format forwarding would also be possible in the kernel
without hindering userspace from doing it themselves later.

regards
Philipp