From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 24 May 2002 17:00:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 24 May 2002 17:00:09 -0400 Received: from 64-166-72-142.ayrnetworks.com ([64.166.72.142]:28552 "EHLO ayrnetworks.com") by vger.kernel.org with ESMTP id ; Fri, 24 May 2002 17:00:09 -0400 Date: Fri, 24 May 2002 13:58:42 -0700 From: William Jhun To: "David S. Miller" Cc: linux-kernel@vger.kernel.org Subject: Re: Possible discrepancy regarding streaming DMA mappings in DMA-mapping.txt? Message-ID: <20020524135842.L7205@ayrnetworks.com> In-Reply-To: <20020524104345.J7205@ayrnetworks.com> <20020524.104209.31440798.davem@redhat.com> <20020524133711.K7205@ayrnetworks.com> <20020524.132641.104219414.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 24, 2002 at 01:26:41PM -0700, David S. Miller wrote: > > I know what you're trying to do, but I'm going to tell you upfront > that this will make the existing case much more inefficient than > it needs to be. Sorry, I'm not clear on this one. I was first proposing (for the short term, at least) to not change anything at all: all the existing implementations of pci_dma_sync_*(..., PCIDMA_TO_DEVICE) already do what is required: prepare the buffer to be DMAed from by the controller. Most drivers won't have to deal with this; most network drivers, for example, do a pci_map_*() on an skb passed down from the stack and subsequently pci_unmap_*() those buffers once transmitted, thus having no need for pci_dma_sync_*()... So I don't see how this makes anything else less efficient... > > Please, add a new call to handle your case. Thanks. Such a call would do what pci_dma_sync_*(..., PCIDMA_TO_DEVICE) already does (unless that is what you want - to have a new call just for the sake of clarity...). Thanks, William