From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755358Ab0JJSxK (ORCPT ); Sun, 10 Oct 2010 14:53:10 -0400 Received: from mail.issp.bas.bg ([195.96.236.10]:38950 "EHLO mail.issp.bas.bg" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563Ab0JJSxI (ORCPT ); Sun, 10 Oct 2010 14:53:08 -0400 From: Marin Mitov Organization: Institute of Solid State Physics To: Guennadi Liakhovetski Subject: Re: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API Date: Sun, 10 Oct 2010 21:48:36 +0300 User-Agent: KMail/1.13.3 (Linux/2.6.36-rc7; KDE/4.4.3; x86_64; ; ) Cc: FUJITA Tomonori , linux-kernel@vger.kernel.org, Linux Media Mailing List References: <201008201113.46036.mitov@issp.bas.bg> <201010101736.54199.mitov@issp.bas.bg> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201010102148.42097.mitov@issp.bas.bg> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday, October 10, 2010 09:21:50 pm Guennadi Liakhovetski wrote: > On Sun, 10 Oct 2010, Marin Mitov wrote: > > > On Sunday, October 10, 2010 05:08:22 pm FUJITA Tomonori wrote: > > > On Fri, 20 Aug 2010 14:50:12 +0300 > > > Marin Mitov wrote: > > > > > > > On Friday, August 20, 2010 11:35:06 am FUJITA Tomonori wrote: > > > > > On Fri, 20 Aug 2010 11:13:45 +0300 > > > > > Marin Mitov wrote: > > > > > > > > > > > > > This tric is already used in drivers/staging/dt3155v4l.c > > > > > > > > dt3155_alloc_coherent()/dt3155_free_coherent() > > > > > > > > > > > > > > > > Here proposed for general use by popular demand from video4linux folks. > > > > > > > > Helps for videobuf-dma-contig framework. > > > > > > > > > > > > > > What you guys exactly want to do? If you just want to pre-allocate > > > > > > > coherent memory for latter usage, > > > > > > > > > > > > Yes, just to preallocate not coherent, but rather contiguous memory for latter usage. > > > > > > We use coherent memory because it turns out to be contiguous. > > > > > > > > > > Hmm, you don't care about coherency? You just need contiguous memory? > > > > > > > > Yes. We just need contiguous memory. Coherency is important as far as when dma > > > > transfer finishes user land is able to see the new data. Could be done by something like > > > > dma_{,un}map_single() > > > > > > Anyone is working on this? > > > > I am not, sorry. > > > > > > > > KAMEZAWA posted a patch to improve the generic page allocator to > > > allocate physically contiguous memory. He said that he can push it > > > into mainline. > > > > I am waiting for the new videobuf2 framework to become part of the kernel. > > Then KAMEZAWA's improvements can help. > > You probably have seen this related thread: > http://marc.info/?t=128644473600004&r=1&w=2 Thanks. Marin Mitov > > Thanks > Guennadi > > > Marin Mitov > > > > > > > > The approach enables us to solve this issue without adding any new > > > API. > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-media" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > --- > Guennadi Liakhovetski, Ph.D. > Freelance Open-Source Software Developer > http://www.open-technology.de/ >