From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261272AbUBTPKb (ORCPT ); Fri, 20 Feb 2004 10:10:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261282AbUBTPKb (ORCPT ); Fri, 20 Feb 2004 10:10:31 -0500 Received: from fw.osdl.org ([65.172.181.6]:61668 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261272AbUBTPK0 (ORCPT ); Fri, 20 Feb 2004 10:10:26 -0500 Date: Fri, 20 Feb 2004 07:15:31 -0800 (PST) From: Linus Torvalds To: "David S. Miller" cc: Benjamin Herrenschmidt , greg@kroah.com, akpm@osdl.org, linux-usb-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [BK PATCH] USB update for 2.6.3 In-Reply-To: <20040219233214.56f5b0ce.davem@redhat.com> Message-ID: References: <20040220012802.GA16523@kroah.com> <1077256996.20789.1091.camel@gaston> <1077258504.20781.1121.camel@gaston> <1077259375.20787.1141.camel@gaston> <20040219230407.063ef209.davem@redhat.com> <1077261041.20787.1181.camel@gaston> <20040219233214.56f5b0ce.davem@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Feb 2004, David S. Miller wrote: > On Fri, 20 Feb 2004 18:10:41 +1100 > Benjamin Herrenschmidt wrote: > > > Hrm... so if the USB device drivers are actually doing the dma mapping > > themselves, it make sense for them to pass their own struct device, no ? > > That's right, at least that was the idea. No. That would be _fundamentally_ wrong. There's no way a USB device can do DMA in the first place. It has no DMA controller, and no way to read/write memory except through the USB host. So it is the host - and only the host - that matters. Anything else is a bug. Linus