From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752776Ab0HZODW (ORCPT ); Thu, 26 Aug 2010 10:03:22 -0400 Received: from sh.osrg.net ([192.16.179.4]:39849 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751093Ab0HZODT (ORCPT ); Thu, 26 Aug 2010 10:03:19 -0400 Date: Thu, 26 Aug 2010 23:03:01 +0900 To: fernando.lugo@ti.com Cc: fujita.tomonori@lab.ntt.co.jp, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, ohad@wizery.com, hiroshi.doyu@nokia.com, ameya.palande@nokia.com, felipe.contreras@nokia.com Subject: RE: [PATCH 8/9] dspbridge: add map support for big buffers From: FUJITA Tomonori In-Reply-To: <496565EC904933469F292DDA3F1663E602F10ED4B3@dlee06.ent.ti.com> References: <496565EC904933469F292DDA3F1663E602F10ED4B1@dlee06.ent.ti.com> <20100826215554N.fujita.tomonori@lab.ntt.co.jp> <496565EC904933469F292DDA3F1663E602F10ED4B3@dlee06.ent.ti.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20100826230139Y.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Thu, 26 Aug 2010 23:03:02 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Aug 2010 08:16:24 -0500 "Guzman Lugo, Fernando" wrote: > >From a quick look, arch/arm/plat-omap/iovmm.c does nothing wrong about > >scatter gather chaining. arm/arm/mm/dma-mapping.c looks fine too about > >it. Maybe just defining ARCH_HAS_SG_CHAIN works? > > I can try, but it looks tricky for me. Maybe someone else can tell us why > SG chain is not supported for ARM or if there is a problem just defining > ARCH_HAS_SG_CHAIN. I suppose that nobody in ARM has been interested in the feature. It was invented to improve I/O performance with large I/O requests. No wonder embeded people aren't interested in it. fujita@rose:~/git/linux-2.6$ find arch -name 'scatterlist.h'|xargs grep HAS_SG arch/x86/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/ia64/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/sparc/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN arch/powerpc/include/asm/scatterlist.h:#define ARCH_HAS_SG_CHAIN