From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:41817 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755828Ab2IXQvo (ORCPT ); Mon, 24 Sep 2012 12:51:44 -0400 Received: from eusync2.samsung.com (mailout4.w1.samsung.com [210.118.77.14]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MAV0074W5J54G60@mailout4.w1.samsung.com> for linux-media@vger.kernel.org; Mon, 24 Sep 2012 17:52:17 +0100 (BST) Received: from [106.116.147.32] by eusync2.samsung.com (Oracle Communications Messaging Server 7u4-23.01(7.0.4.23.0) 64bit (built Aug 10 2011)) with ESMTPA id <0MAV008TE5I5M220@eusync2.samsung.com> for linux-media@vger.kernel.org; Mon, 24 Sep 2012 17:51:42 +0100 (BST) Message-id: <50608F9D.40304@samsung.com> Date: Mon, 24 Sep 2012 18:51:41 +0200 From: Sylwester Nawrocki MIME-version: 1.0 To: Sakari Ailus Cc: linux-media@vger.kernel.org, a.hajda@samsung.com, laurent.pinchart@ideasonboard.com, hverkuil@xs4all.nl, kyungmin.park@samsung.com, sw0312.kim@samsung.com Subject: Re: [PATCH RFC] V4L: Add s_rx_buffer subdev video operation References: <1348493213-32278-1-git-send-email-s.nawrocki@samsung.com> <20120924134453.GH12025@valkosipuli.retiisi.org.uk> In-reply-to: <20120924134453.GH12025@valkosipuli.retiisi.org.uk> Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On 09/24/2012 03:44 PM, Sakari Ailus wrote: > How about useing a separate video buffer queue for the purpose? That would > provide a nice way to pass it to the user space where it's needed. It'd also > play nicely together with the frame layout descriptors. It's tempting, but doing frame synchronisation in user space in this case would have been painful, if at all possible in reliable manner. It would have significantly complicate applications and the drivers. VIDIOC_STREAMON, VIDIOC_QBUF/DQBUF calls would have been at least roughly synchronized, and applications would have to know somehow which video nodes needs to be opened together. I guess things like that could be abstracted in a library, but what do we really gain for such effort ? And now I can just ask kernel for 2-planar buffers where everything is in place.. Regards, Sylwester