From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756066Ab1HST0r (ORCPT ); Fri, 19 Aug 2011 15:26:47 -0400 Received: from dsl-67-204-24-19.acanac.net ([67.204.24.19]:35967 "EHLO mail.ellipticsemi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755684Ab1HST0q (ORCPT ); Fri, 19 Aug 2011 15:26:46 -0400 Date: Fri, 19 Aug 2011 15:26:38 -0400 From: Nick Bowler To: Jamie Iles Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Russell King Subject: Re: [PATCH RFC] ARM: vexpress: Use assembler mnemonic for WFI in platform_do_lowpower. Message-ID: <20110819192638.GA21043@elliptictech.com> References: <1313777004-4716-1-git-send-email-nbowler@elliptictech.com> <20110819181514.GA12654@gallagher> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110819181514.GA12654@gallagher> Organization: Elliptic Technologies Inc. User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2011-08-19 19:15 +0100, Jamie Iles wrote: > On Fri, Aug 19, 2011 at 02:03:24PM -0400, Nick Bowler wrote: [...] > > - /* > > - * here's the WFI > > - */ > > - asm(".word 0xe320f003\n" > > + asm("wfi\n" > > : > > : > > : "memory", "cc"); > > There's a wfi() macro defined in arch/arm/include/asm/system.h that > could be used here. Indeed, thanks for pointing that out. I'm a little wary, however: the wfi macro does not include the "cc" clobber that this code has currently, and I don't know what the implications of removing it are. There appears to be no current users of the wfi macro. Taking a closer look, there appear to be five platforms that have a hardcoded WFI just like the above (including the "cc" clobber): exynos4, realview, shmobile, tegra and vexpress. omap defines its own do_wfi macro, *without* the "cc" clobber. Nevertheless, using the macro seems to work just fine, so I can certainly re-spin the patch with that instead. -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)