From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: FOR COMMENT: void __iomem * and similar casts are Bad News Date: Wed, 3 Sep 2008 15:05:59 -0700 Message-ID: <200809031506.00261.david-b@pacbell.net> References: <20080827220821.GE7227@flint.arm.linux.org.uk> <200809031418.44929.david-b@pacbell.net> <13B9B4C6EF24D648824FF11BE8967162036545FC7D@dlee02.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp115.sbc.mail.sp1.yahoo.com ([69.147.64.88]:37895 "HELO smtp115.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751140AbYICWGD (ORCPT ); Wed, 3 Sep 2008 18:06:03 -0400 In-Reply-To: <13B9B4C6EF24D648824FF11BE8967162036545FC7D@dlee02.ent.ti.com> Content-Disposition: inline Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Woodruff, Richard" Cc: Russell King - ARM Linux , Tony Lindgren , "linux-omap@vger.kernel.org" , Eduardo Valentin On Wednesday 03 September 2008, Woodruff, Richard wrote: > > > ... [ big/inexpensive fixed mappings can be virtuous ... ] > > > > ... which is exactly why some linux/arch/... code makes sure iorema= p() > > can return fixed mappings instead of always requiring dynamic ones. >=20 > That does sound like a nice consistent way to do it. =A0Which impleme= ntation > of this would you recommend looking at? =A0Do any ARMs you know of do= it today?=20 I was just calling attention to the possibility. ISTR seeing that AVR32 does that, and I think some MIPS hardware has the same kind of logic. Not just those, either. The ARM stuff seems to have changed since last I looked! In arch/arm/include/asm/io.h there's an __arch_ioremap() hook; it could be used instead of __arm_ioremap() ... and it seems would define __arch_ioremap(). So at a first glance, OMAPs _could_ define that arch function to look at the physical address to see if it's covered by a fixed mapping, then reuse it ... else use __arm_ioremap(). According to Mr. Grep, there are at least 10 ARMs that work like that in mainline. Maybe Russell can recommend one of them as a preferred model. - Dave -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html