From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from 132.79-246-81.adsl-static.isp.belgacom.be ([81.246.79.132]:36092 "EHLO viper.mind.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754293Ab0CCONC (ORCPT ); Wed, 3 Mar 2010 09:13:02 -0500 Received: from [10.3.4.27] (helo=vandecaa-laptop.localnet) by viper.mind.be with esmtp (Exim 4.69) (envelope-from ) id 1NmpJe-0004mT-D9 for linux-media@vger.kernel.org; Wed, 03 Mar 2010 15:13:01 +0100 From: Arnout Vandecappelle To: linux-media@vger.kernel.org Subject: Support for zerocopy to DSP on OMAP3 Date: Wed, 3 Mar 2010 15:12:44 +0100 MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201003031512.45428.arnout@mind.be> Sender: linux-media-owner@vger.kernel.org List-ID: Hoi, [Please CC me, I'm not subscribed.] I'm implementing zerocopy transfer from a v4l2 camera to the DSP on an OMAP3 (based on earlier work by Stefan Kost [1][2]). Therefore I'm using V4L2_MEMORY_USERPTR to pass in the memory area allocated by TI's DMAI driver. However, this has flags VM_IO | VM_PFNMAP. This means that it is not possible to do get_user_pages() on it - it's an area that is not pageable and possibly even doesn't pass the MMU. In order to support this kind of zerocopy construct, I propose to add checks for VM_IO | VM_PFNMAP and only get pages from areas that don't have these flags set. If I get positive feedback on this, I'll supply a patch. [1] https://bugzilla.gnome.org/show_bug.cgi?id=583890 [2] http://thread.gmane.org/gmane.linux.drivers.video-input- infrastructure/6209 -- Arnout Vandecappelle arnout at mind be Senior Embedded Software Architect +32-16-286540 Essensium/Mind http://www.mind.be G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle GPG fingerprint: 31BB CF53 8660 6F88 345D 54CC A836 5879 20D7 CF43