Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264972AbUFSAIf (ORCPT ); Fri, 18 Jun 2004 20:08:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265273AbUFSAIK (ORCPT ); Fri, 18 Jun 2004 20:08:10 -0400 Received: from stat1.steeleye.com ([65.114.3.130]:64986 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S264972AbUFSAEV (ORCPT ); Fri, 18 Jun 2004 20:04:21 -0400 Subject: Re: DMA API issues From: James Bottomley To: Ian Molton Cc: david-b@pacbell.net, Linux Kernel , greg@kroah.com, tony@atomide.com, jamey.hicks@hp.com, joshua@joshuawise.com In-Reply-To: <20040619005106.15b8c393.spyro@f2s.com> References: <1087582845.1752.107.camel@mulgrave> <20040618193544.48b88771.spyro@f2s.com> <1087584769.2134.119.camel@mulgrave> <20040618195721.0cf43ec2.spyro@f2s.com> <40D34078.5060909@pacbell.net> <20040618204438.35278560.spyro@f2s.com> <1087588627.2134.155.camel@mulgrave> <20040619002522.0c0d8e51.spyro@f2s.com> <1087601363.2078.208.camel@mulgrave> <20040619005106.15b8c393.spyro@f2s.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-9) Date: 18 Jun 2004 19:04:11 -0500 Message-Id: <1087603453.2135.224.camel@mulgrave> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1126 Lines: 27 On Fri, 2004-06-18 at 18:51, Ian Molton wrote: > Im aware of that but the OHCI core doesnt do that, it uses the DMA API, > which is entirely reasonable, given its tring to access a DMA-able chunk > of memory. > > I *could* write a new driver ohci-ioremapped for all these chips but its > needless duplication which is going to result in bugs bveing fixed in > one ohci driver and not the other. > > why not simply expand the DMA API to allow DMA to these easily DMA-able > chips ? Because the piece of memory you wish to access is bus remote. Our current API for bus remote memory requires the use of ioremap and the accessor functions. Just because it could be accessed directly on ARM doesn't mean it can be on all platforms. The DMA API is a platform generic API. To propose an addition to it to make use of this memory, it would have to work on *all* platforms. James - 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/