From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:42896 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753888Ab2IXRFa (ORCPT ); Mon, 24 Sep 2012 13:05:30 -0400 Received: from eusync1.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 <0MAV00F256634T90@mailout4.w1.samsung.com> for linux-media@vger.kernel.org; Mon, 24 Sep 2012 18:06:03 +0100 (BST) Received: from [106.116.147.32] by eusync1.samsung.com (Oracle Communications Messaging Server 7u4-23.01(7.0.4.23.0) 64bit (built Aug 10 2011)) with ESMTPA id <0MAV00HUO6539I50@eusync1.samsung.com> for linux-media@vger.kernel.org; Mon, 24 Sep 2012 18:05:28 +0100 (BST) Message-id: <506092D7.9040807@samsung.com> Date: Mon, 24 Sep 2012 19:05:27 +0200 From: Sylwester Nawrocki MIME-version: 1.0 To: Laurent Pinchart Cc: Sakari Ailus , linux-media@vger.kernel.org, a.hajda@samsung.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> <8816374.onnX7s7R5d@avalon> In-reply-to: <8816374.onnX7s7R5d@avalon> Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Laurent, On 09/24/2012 03:58 PM, Laurent Pinchart 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. > > Beside, a void *buf wouldn't support DMA. Only subdevs that use PIO to > transfer meta data could be supported by this. I guess most of MIPI-CSI2 receivers out there support data capture from distinct Data Types into separate DMA buffers. But not this one. In case of multi-context DMA engine I guess MIPI-CSI2 receiver driver would expose video node anyway and it wouldn't need such a callback at all ? Perhaps using struct v4l2_subdev_core_ops::ioctl would be more appropriate here ? -- Regards, Sylwester