From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756885AbYAFSCQ (ORCPT ); Sun, 6 Jan 2008 13:02:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754553AbYAFSCB (ORCPT ); Sun, 6 Jan 2008 13:02:01 -0500 Received: from einhorn.in-berlin.de ([192.109.42.8]:60258 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754335AbYAFSCA (ORCPT ); Sun, 6 Jan 2008 13:02:00 -0500 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <47811770.4040706@s5r6.in-berlin.de> Date: Sun, 06 Jan 2008 19:01:20 +0100 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.11) Gecko/20071216 SeaMonkey/1.1.7 MIME-Version: 1.0 To: Al Boldi CC: Sam Ravnborg , Adrian Bunk , Randy Dunlap , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, David Brownell , Greg KH , Andrew Morton Subject: Re: [PATCH 2/5] USB Kconfig: Select SCSI for USB Mass Storage support References: <200801051546.SAA08947@raad.intranet> <200801060803.27101.a1426z@gawab.com> <4780E814.4050405@s5r6.in-berlin.de> <200801062007.31516.a1426z@gawab.com> <478114F3.6020804@s5r6.in-berlin.de> In-Reply-To: <478114F3.6020804@s5r6.in-berlin.de> X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stefan Richter wrote: > Al Boldi wrote: >> Stefan Richter wrote: >>> Still wrong. SCSI also needs HAS_DMA and SCSI_DMA. >> I don't think so. SCSI selects SCSI_DMA, it doesn't depend on it. > > "A selects B" == "A depends on B, but please don't hide A when B is off > and silently switch B on when A is switched on". > > config SCSI > tristate "SCSI device support" > depends on BLOCK > select SCSI_DMA if HAS_DMA > > So, SCSI doesn't actually need SCSI_DMA per se, but it apparently needs > it whenever HAS_DMA != n. In fact, only a number of SCSI low-level drivers need SCSI_DMA. But libata and usb-storage are currently not among those drivers. For them it's currently harmless if SCSI_DMA is off. SCSI_DMA only includes the symbols scsi_dma_map() and scsi_dma_unmap() into the scsi core. libata and usb-storage don't call these. -- Stefan Richter -=====-==--- ---= --==- http://arcgraph.de/sr/