From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:45277 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932428AbeFFKvS (ORCPT ); Wed, 6 Jun 2018 06:51:18 -0400 Date: Wed, 6 Jun 2018 12:51:16 +0200 From: Pavel Machek To: Tomasz Figa Cc: mchehab+samsung@kernel.org, mchehab@s-opensource.com, Hans Verkuil , pali.rohar@gmail.com, sre@kernel.org, Sakari Ailus , Linux Media Mailing List , Hans Verkuil Subject: Re: [RFC, libv4l]: Make libv4l2 usable on devices with complex pipeline Message-ID: <20180606105116.GA4328@amd> References: <20180319120043.GA20451@amd> <20180319095544.7e235a3e@vento.lan> <20180515200117.GA21673@amd> <20180515190314.2909e3be@vento.lan> <20180602210145.GB20439@amd> <20180606084612.GB18743@amd> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HcAYCG3uE/tztfnV" Content-Disposition: inline In-Reply-To: Sender: linux-media-owner@vger.kernel.org List-ID: --HcAYCG3uE/tztfnV Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable HI! > > > Thanks for coming up with this proposal. Please see my comments below. > > > > > > > Ok, can I get any comments on this one? > > > > v4l2_open_complex("/file/with/descriptor", 0) can be used to open > > > > whole pipeline at once, and work if it as if it was one device. > > > > > > I'm not convinced if we should really be piggy backing on libv4l, but > > > it's just a matter of where we put the code added by your patch, so > > > let's put that aside. > > > > There was some talk about this before, and libv4l2 is what we came > > with. Only libv4l2 is in position to propagate controls to right > > devices. > > > > > Who would be calling this function? > > > > > > The scenario that I could think of is: > > > - legacy app would call open(/dev/video?), which would be handled by > > > libv4l open hook (v4l2_open()?), > > > > I don't think that kind of legacy apps is in use any more. I'd prefer > > not to deal with them. >=20 > In another thread ("[ANN v2] Complex Camera Workshop - Tokyo - Jun, > 19"), Mauro has mentioned a number of those: >=20 > "open source ones (Camorama, Cheese, Xawtv, Firefox, Chromium, ...) and c= losed > source ones (Skype, Chrome, ...)" Thanks for thread pointer... I may be able to get in using hangouts. Anyway, there's big difference between open("/dev/video0") and v4l2_open("/dev/video0"). I don't care about the first one, but yes we should be able to support the second one eventually. And I don't think Mauro says apps like Camorama are of open() kind. Best regards, Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --HcAYCG3uE/tztfnV Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlsXvKQACgkQMOfwapXb+vLV/gCfYQ992IPW3zRvLE5ZqohCvxDb 3O0AoKoVK/7VmDEV9XfxcdzgHx582xtb =jCWR -----END PGP SIGNATURE----- --HcAYCG3uE/tztfnV--