From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:57683 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751928Ab1DEMw7 (ORCPT ); Tue, 5 Apr 2011 08:52:59 -0400 From: Laurent Pinchart To: Hans Verkuil Subject: Re: [PATCH/RFC 1/4] V4L: add three new ioctl()s for multi-size videobuffer management Date: Tue, 5 Apr 2011 14:53:32 +0200 Cc: "Hans Verkuil" , "Guennadi Liakhovetski" , "Linux Media Mailing List" , "Mauro Carvalho Chehab" References: <201104051402.17836.laurent.pinchart@ideasonboard.com> <201104051440.16449.hansverk@cisco.com> In-Reply-To: <201104051440.16449.hansverk@cisco.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201104051453.33013.laurent.pinchart@ideasonboard.com> List-ID: Sender: On Tuesday 05 April 2011 14:40:16 Hans Verkuil wrote: > On Tuesday, April 05, 2011 14:02:17 Laurent Pinchart wrote: > > On Monday 04 April 2011 10:06:47 Hans Verkuil wrote: > > > > On Mon, 4 Apr 2011, Hans Verkuil wrote: > > > >> On Friday, April 01, 2011 10:13:02 Guennadi Liakhovetski wrote: > > [snip] > > > > > BTW, REQBUFS and CREATE/DESTROY_BUFS should definitely co-exist. > > > REQBUFS is compulsory, while CREATE/DESTROY are optional. > > > > Drivers must support REQBUFS and should support CREATE/DESTROY, but I > > think applications should not be allowed to mix calls. > > Why not? The videobuf2-core.c implementation shouldn't care about that, so > I don't see why userspace should care. Because it makes the API semantics much more complex to define. We would have to precisely define interactions between REQBUFS and CREATE/DESTROY. That will be error-prone, for very little benefits (if any at all). If an application is aware of the CREATE/DESTROY ioctls and wants to use them, why would it need to use REQBUFS ? -- Regards, Laurent Pinchart