From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757486Ab0JJSVd (ORCPT ); Sun, 10 Oct 2010 14:21:33 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:48733 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1751658Ab0JJSVc (ORCPT ); Sun, 10 Oct 2010 14:21:32 -0400 X-Authenticated: #20450766 X-Provags-ID: V01U2FsdGVkX19x1Md4kfFxpORceqjIfWx9W/fJrOZ5RoIuul8uLa 2KYIas4UbiS6gP Date: Sun, 10 Oct 2010 20:21:50 +0200 (CEST) From: Guennadi Liakhovetski To: Marin Mitov cc: FUJITA Tomonori , linux-kernel@vger.kernel.org, Linux Media Mailing List Subject: Re: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API In-Reply-To: <201010101736.54199.mitov@issp.bas.bg> Message-ID: References: <201008201113.46036.mitov@issp.bas.bg> <201008201450.12585.mitov@issp.bas.bg> <20101010230323B.fujita.tomonori@lab.ntt.co.jp> <201010101736.54199.mitov@issp.bas.bg> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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/