From owner-freebsd-hackers@FreeBSD.ORG Thu Jul 5 21:02:58 2007 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 8D90B16A475 for ; Thu, 5 Jul 2007 21:02:58 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (66-23-211-162.clients.speedfactory.net [66.23.211.162]) by mx1.freebsd.org (Postfix) with ESMTP id 384EE13C468 for ; Thu, 5 Jul 2007 21:02:57 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from localhost.corp.yahoo.com (john@localhost [127.0.0.1]) (authenticated bits=0) by server.baldwin.cx (8.13.8/8.13.8) with ESMTP id l65L2pdX027348; Thu, 5 Jul 2007 17:02:53 -0400 (EDT) (envelope-from jhb@freebsd.org) From: John Baldwin To: freebsd-hackers@freebsd.org Date: Thu, 5 Jul 2007 16:25:17 -0400 User-Agent: KMail/1.9.6 References: <200707040901.33019.hselasky@c2i.net> <20070704173531.GO1221@funkthat.com> <200707050931.59256.hselasky@c2i.net> In-Reply-To: <200707050931.59256.hselasky@c2i.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707051625.17954.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (server.baldwin.cx [127.0.0.1]); Thu, 05 Jul 2007 17:02:53 -0400 (EDT) X-Virus-Scanned: ClamAV 0.88.3/3606/Thu Jul 5 13:50:01 2007 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=4.2 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on server.baldwin.cx Cc: John-Mark Gurney , freebsd-usb@freebsd.org, Hans Petter Selasky Subject: Re: New USB stack and Zero copy. X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 Jul 2007 21:02:58 -0000 On Thursday 05 July 2007 03:31:59 am Hans Petter Selasky wrote: > On Wednesday 04 July 2007 19:35, John-Mark Gurney wrote: > > Hans Petter Selasky wrote this message on Wed, Jul 04, 2007 at 09:01 +0200: > > > Also: How is the easiest way to load memory pages into DMA ? And I want > > > that the loadig works like this, that when the page must be bounced it > > > should not allocate a bounce buffer, hence I already have a bounce > > > buffer. I only need to know which pages I can forward directly to the USB > > > hardware, and the rest I will bounce somewhere else. > > > > Why do you not want to let bus_dma do the bouncing for you? If it's > > to save a copy to another buffer, why don't you load the final buffer > > into bus_dma? > > Because if I let bus_dma do the bounching, I cannot do this while holding a > mutex, hence allocating DMA'able memory on the fly is not so good. This is not a hard problem to solve, every other driver using bus_dma solves it. Just make sure your driver is in a sane state and drop the lock while you let bus_dmamap_load() map/copy things for you. -- John Baldwin