Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760100AbXIRWRn (ORCPT ); Tue, 18 Sep 2007 18:17:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758027AbXIRWRO (ORCPT ); Tue, 18 Sep 2007 18:17:14 -0400 Received: from gate.crashing.org ([63.228.1.57]:54121 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757383AbXIRWRM (ORCPT ); Tue, 18 Sep 2007 18:17:12 -0400 Subject: Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices From: Benjamin Herrenschmidt To: Linus Torvalds Cc: "Luis R. Rodriguez" , Alan Cox , linux-kernel , Jeff Garzik , "John W. Linville" , linux-wireless In-Reply-To: References: <43e72e890709171322x76ab6b70xd29bf97e3643c553@mail.gmail.com> <20070918113401.6a8a737f@the-village.bc.nu> <43e72e890709181146s604e0f9fl8b0c16627469c77f@mail.gmail.com> Content-Type: text/plain Date: Wed, 19 Sep 2007 08:16:14 +1000 Message-Id: <1190153775.6403.120.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1285 Lines: 37 On Tue, 2007-09-18 at 12:03 -0700, Linus Torvalds wrote: > > On Tue, 18 Sep 2007, Luis R. Rodriguez wrote: > > > > Alright, here is the same patch inline with s/recommended/required/ language: > > Well, the thing is, I'm not at all sure that I agree with this. > > If you use ioport_map/unmap, then you really *should* access them with the > proper iomem accessors (ioread/iowrite). The fact that it may happen to > work (when using the default lib/iomap.c implementation, at least) on > some architectures and with the current implementation still doesn't mean > that you should necessarily use readb/writeb. > > After all, you cannot use "inb/outb" on it, even if would happen to be an > IO address. > > So what is this usage that wants to use the bogus accessor? Why not fix > that instead of adding documentation for something that is very arguably > something we want to *avoid* having people do! Agreed. ioremap -> readb/writeb ioport_map/pci_iomap -> ioread/iowrite and nothing else should be allowed. Cheers, Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/