From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756359AbXIRTD7 (ORCPT ); Tue, 18 Sep 2007 15:03:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753734AbXIRTDv (ORCPT ); Tue, 18 Sep 2007 15:03:51 -0400 Received: from an-out-0708.google.com ([209.85.132.245]:15828 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753535AbXIRTDt (ORCPT ); Tue, 18 Sep 2007 15:03:49 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=TRiYeZCX7advny6ZotlwGXRm7KtdXvOyBTkke9qW23spHFokDzMK5J2mu6tRWMFNVZAYPgWtjVTeO6fLdjZj2vk6FaFBvADy9GeikW/mQJdVs6+2LE+wpaKX6v9et8nvaC6BUuxlX2Ob/5tv98xezhGvO4Bpa6kJ1CDCD3RwyZE= Message-ID: <43e72e890709181203x30144451hf332da4032b5b770@mail.gmail.com> Date: Tue, 18 Sep 2007 15:03:48 -0400 From: "Luis R. Rodriguez" To: "Jiri Slaby" Subject: Re: [PATCH] revert ath5k ioread32()/iowrite32() usage - use readl()/writel(), we're MMIO-only Cc: "Jeff Garzik" , "John W. Linville" , linux-wireless , "Alan Cox" , "Linux Kernel Mailing List" In-Reply-To: <46EEF543.7060901@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <43e72e890709171334y321dc2c8ke255a126a733dad6@mail.gmail.com> <46EEE735.5050306@gmail.com> <46EEEA9B.70407@garzik.org> <46EEF543.7060901@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 9/17/07, Jiri Slaby wrote: > On 09/17/2007 10:59 PM, Jeff Garzik wrote: > > Jiri Slaby wrote: > >> NACK, this is wrong. iomap returns platform dependant return value, > >> which may or > > > > Incorrect. readl() and writel() work just fine on all existing > > platforms where Atheros may be used. > > Ok, this is what Alan Cox wrote about that and you didn't reply to it, so I > thought he's right. Anyway I wouldn't rely on iomap that it will never be > changed even on x86 -- what's the (performance) impact of having ioread instead > of readl? How much data are transferred this way? > > > On Sat, 25 Aug 2007 04:56:19 -0400 > Jeff Garzik wrote: > > > If the driver knows its MMIO, using readX/writeX after pci_iomap() is > > just fine, for all current implementations, and it makes sense that way. > > There is nothing that guarantees this is permitted, any more than there > is anything saying not to use outb/outl. Some of the implementations do > quite strange things. It may happen to work but its not in the > documentation or the comments. I posted a patch to update the documentation with this. > Please, can anybody clarify it? Based on Alan's 'Review-by' remarks on my patch for updating the documenation on pci_iomap() it seems this validates this patch. Please see thread with subject: [PATCH] Clarify pci_iomap() usage for MMIO-only devices Luis