From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: Proposals to change the way all drivers work with SCSI commands Date: Fri, 11 May 2007 16:12:47 -0500 Message-ID: <1178917967.3692.70.camel@mulgrave.il.steeleye.com> References: <1178908422.3692.58.camel@mulgrave.il.steeleye.com> <20070511.130024.104034874.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from hancock.steeleye.com ([71.30.118.248]:52188 "EHLO hancock.sc.steeleye.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1761105AbXEKVMv (ORCPT ); Fri, 11 May 2007 17:12:51 -0400 In-Reply-To: <20070511.130024.104034874.davem@davemloft.net> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: David Miller Cc: linux-scsi@vger.kernel.org On Fri, 2007-05-11 at 13:00 -0700, David Miller wrote: > From: James Bottomley > Date: Fri, 11 May 2007 13:33:41 -0500 > > > Right at the moment, we're planning to clean up the way SCSI drivers > > process commands. The proposals are essentially: > > > > 1. Get rid of the now unnecessary map_single path (every command is > > either zero transfer or scatter/gather) > > 2. use accessors to manipulate the SG lists (mainly so that we can > > alter the implementation without affecting the drivers) > > > > It strikes me that in all of this, we could also consider doing the DMA > > mapping inside the mid layer (instead of in every driver). This is > > essentially what libata is already doing ... leading to confusion in > > SCSI drivers that use libata for SATA. > > > > So what do people think about this? > > This would require platforms to handle all of their bus types > behind the generic dma_*() and that's isn't true everywhere yet. > > For example, SBUS still requires explicitly using sbus_map_sg() etc. > > I plan to fix that of course, but we're not there now. I could probably cook up a patch for you, if you like? ... I've already done it for several other architectures. James