Date: Sun, 26 Mar 2017 11:12:57 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Steve Longerbeam <slongerbeam@gmail.com>,
        Russell King - ARM Linux <linux@armlinux.org.uk>, mark.rutland@arm.com,
        andrew-ct.chen@mediatek.com, minghsiu.tsai@mediatek.com,
        nick@shmanahar.org, songjun.wu@microchip.com,
        Hans Verkuil <hverkuil@xs4all.nl>, shuah@kernel.org,
        devel@driverdev.osuosl.org, markus.heiser@darmarIT.de,
        laurent.pinchart+renesas@ideasonboard.com, robert.jarzmik@free.fr,
        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 <sakari.ailus@iki.fi>,
        jean-christophe.trotin@st.com, sakari.ailus@linux.intel.com,
        fabio.estevam@nxp.com, shawnguo@kernel.org, sudipm.mukherjee@gmail.com
Subject: script to setup pipeline was Re: [PATCH v4 14/36] [media] v4l2-mc:
 add a function to inherit controls from a pipeline
Message-ID: <20170326091257.GA17728@amd>
References: <20170311101408.272a9187@vento.lan>
 <20170311153229.yrdjmggb3p2suhdw@ihha.localdomain>
 <acfb5eca-ff00-6d57-339a-3322034cbdb3@gmail.com>
 <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>
 <fba73c10-4b95-f0d2-e681-0b14ef1fbc1c@gmail.com>
 <20170312185845.5c18ffd0@vento.lan>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
        protocol="application/pgp-signature"; boundary="45Z9DzgjV8m4Oswq"
Content-Disposition: inline
In-Reply-To: <20170312185845.5c18ffd0@vento.lan>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2425
Lines: 68


--45Z9DzgjV8m4Oswq
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Hi!

> > I do agree with you that MC places a lot of burden on the user to
> > attain a lot of knowledge of the system's architecture.
>=20
> Setting up the pipeline is not the hard part. One could write a
> script to do that.=20

Can you try to write that script? I believe it would solve big part of
the problem.

> > And my other point is, I think most people who have a need to work with
> > the media framework on a particular platform will likely already be
> > quite familiar with that platform.
>=20
> I disagree. The most popular platform device currently is Raspberry PI.
>=20
> I doubt that almost all owners of RPi + camera module know anything
> about MC. They just use Raspberry's official driver with just provides
> the V4L2 interface.
>=20
> I have a strong opinion that, for hardware like RPi, just the V4L2
> API is enough for more than 90% of the cases.

Maybe V4L2 API is enough for 90% of the users. But I don't believe
that means that we should provide compatibility. V4L2 API is not good
enough for complex devices, and if we can make RPi people fix
userspace... that's a good thing.

> > The media graph for imx6 is fairly self-explanatory in my opinion.
> > Yes that graph has to be generated, but just with a simple 'media-ctl
> > --print-dot', I don't see how that is difficult for the user.
>=20
> Again, IMHO, the problem is not how to setup the pipeline, but, instead,
> the need to forward controls to the subdevices.
>=20
> To use a camera, the user needs to set up a set of controls for the
> image to make sense (bright, contrast, focus, etc). If the driver
> doesn't forward those controls to the subdevs, an application like
> "camorama" won't actually work for real, as the user won't be able
> to adjust those parameters via GUI.

I believe this can be fixed in libv4l2.
								Pavel
--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

--45Z9DzgjV8m4Oswq
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iEYEARECAAYFAljXhhkACgkQMOfwapXb+vI2pgCfVZ5AHsBdDv5WQPiCdCAa7ea4
kjkAnRvsjbRH8D5GAj3SxXqJPU94KdQD
=l5bl
-----END PGP SIGNATURE-----

--45Z9DzgjV8m4Oswq--