Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753515Ab0HZM47 (ORCPT ); Thu, 26 Aug 2010 08:56:59 -0400 Received: from sh.osrg.net ([192.16.179.4]:34257 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752502Ab0HZM45 (ORCPT ); Thu, 26 Aug 2010 08:56:57 -0400 Date: Thu, 26 Aug 2010 21:56:45 +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: <496565EC904933469F292DDA3F1663E602F10ED4B1@dlee06.ent.ti.com> References: <1277943660-4112-9-git-send-email-x0095840@ti.com> <20100826155416J.fujita.tomonori@lab.ntt.co.jp> <496565EC904933469F292DDA3F1663E602F10ED4B1@dlee06.ent.ti.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20100826215554N.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 21:56:46 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1093 Lines: 20 On Thu, 26 Aug 2010 07:38:26 -0500 "Guzman Lugo, Fernando" wrote: > >> due to a restriction in scatter gather lists, it can > >> not be created a list for a buffer bigger than 1MB. > >> This patch is spliting big mappings into 1MB mappings. > > > >I don't read the whole thread but the above description is incorrect. > > > >Why can't you use scatter gather chaining? You can create a scatter > >list for a buffer larger than 1MB. > > The thing is that ARM architecture does not support SG chaining. This patch should be > seen like a workaround until it is fixed in iovmm module. Fix iovmm module is easier than the workaround? >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? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/