From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qt0-f194.google.com ([209.85.216.194]:35146 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751950AbdKQM1Q (ORCPT ); Fri, 17 Nov 2017 07:27:16 -0500 Date: Fri, 17 Nov 2017 10:27:10 -0200 From: Gustavo Padovan To: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, Hans Verkuil , Shuah Khan , Pawel Osciak , Alexandre Courbot , Sakari Ailus , Brian Starkey , Thierry Escande , linux-kernel@vger.kernel.org, Gustavo Padovan Subject: Re: [RFC v5 03/11] [media] vb2: add 'ordered_in_driver' property to queues Message-ID: <20171117122710.GF19033@jade> References: <20171115171057.17340-1-gustavo@padovan.org> <20171115171057.17340-4-gustavo@padovan.org> <20171117101559.455cced3@vento.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171117101559.455cced3@vento.lan> Sender: linux-media-owner@vger.kernel.org List-ID: Hi Mauro, 2017-11-17 Mauro Carvalho Chehab : > Em Wed, 15 Nov 2017 15:10:49 -0200 > Gustavo Padovan escreveu: > > > From: Gustavo Padovan > > > > We use ordered_in_driver property to optimize for the case where > > the driver can deliver the buffers in an ordered fashion. When it > > is ordered we can use the same fence context for all fences, but > > when it is not we need to a new context for each out-fence. > > > > So the ordered_in_driver flag will help us with identifying the queues > > that can be optimized and use the same fence context. > > > > v4: make the property a vector for optimization and not a mandatory thing > > that drivers need to set if they want to use explicit synchronization. > > > > v3: improve doc (Hans Verkuil) > > > > v2: rename property to 'ordered_in_driver' to avoid confusion > > > > Signed-off-by: Gustavo Padovan > > --- > > include/media/videobuf2-core.h | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h > > index ef9b64398c8c..38b9c8dd42c6 100644 > > --- a/include/media/videobuf2-core.h > > +++ b/include/media/videobuf2-core.h > > @@ -440,6 +440,12 @@ struct vb2_buf_ops { > > * @fileio_read_once: report EOF after reading the first buffer > > * @fileio_write_immediately: queue buffer after each write() call > > * @allow_zero_bytesused: allow bytesused == 0 to be passed to the driver > > + * @ordered_in_driver: if the driver can guarantee that the queue will be > > + * ordered or not, i.e., the buffers are dequeued from the driver > > + * in the same order they are queued to the driver. The default > > + * is not ordered unless the driver sets this flag. Setting it > > + * when ordering can be guaranted helps to optimize explicit > > + * fences. > > * @quirk_poll_must_check_waiting_for_buffers: Return POLLERR at poll when QBUF > > * has not been called. This is a vb1 idiom that has been adopted > > * also by vb2. > > @@ -510,6 +516,7 @@ struct vb2_queue { > > unsigned fileio_read_once:1; > > unsigned fileio_write_immediately:1; > > unsigned allow_zero_bytesused:1; > > + unsigned ordered_in_driver:1; > > As this may depend on the format, it is probably a good idea to set > this flag either via a function argument or by a function that > would be meant to update it, as video format changes. Right, and maybe I can find a way to store this in only one place, istead of what I did here (having to set explicitely both the ordered_in_driver and the flag separatedly) Gustavo