From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756823AbYKES2Q (ORCPT ); Wed, 5 Nov 2008 13:28:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752613AbYKES2A (ORCPT ); Wed, 5 Nov 2008 13:28:00 -0500 Received: from www.tglx.de ([62.245.132.106]:41414 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752597AbYKES17 (ORCPT ); Wed, 5 Nov 2008 13:27:59 -0500 Date: Wed, 5 Nov 2008 19:27:44 +0100 From: "Hans J. Koch" To: Mike Frysinger Cc: Greg KH , "Hans J. Koch" , Mike Frysinger , linux-kernel@vger.kernel.org Subject: Re: [PATCH] UIO: only call pgprot_noncached if defined Message-ID: <20081105182743.GE6382@local> References: <1225301177-21406-1-git-send-email-vapier@gentoo.org> <20081105113610.GA6382@local> <20081105163334.GA8473@suse.de> <8bd0f97a0811050933m13addb7eiddb963bfdf4d7416@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8bd0f97a0811050933m13addb7eiddb963bfdf4d7416@mail.gmail.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 05, 2008 at 12:33:37PM -0500, Mike Frysinger wrote: > On Wed, Nov 5, 2008 at 11:33, Greg KH wrote: > > On Wed, Nov 05, 2008 at 12:36:11PM +0100, Hans J. Koch wrote: > >> There seem to be archs that cannot easily implement a sensible > >> pgprot_noncached() function, so we should merge this patch. UIO doesn't > >> compile on these archs right now. > > > > No, we should fix those arches to have that function at least NULLed > > out. Isn't there only one, Blackfin? Putting #ifdefs in .c files is > > not something we really want to do if at all possible. > > that was my question. this function isnt documented. if the hardware > doesnt support it, is the right thing really for the arch to lie to > drivers and not actually give back cached settings even though it > asked for non-cached ? Well, if there's no possibility to map device memory in a non-cached way, it's very likely you don't want to use UIO at all. If there's a few seconds between a write and the value actually appearing in the hardware register, you will certainly don't see the results you expect. If Blackfin can't mmap non-cached memory, we should make UIO depend on !BLACKFIN. Hans