Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759776AbXHJHd5 (ORCPT ); Fri, 10 Aug 2007 03:33:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753974AbXHJHdr (ORCPT ); Fri, 10 Aug 2007 03:33:47 -0400 Received: from mail.hevs.ch ([153.109.23.15]:43276 "EHLO mail.hevs.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753834AbXHJHdq convert rfc822-to-8bit (ORCPT ); Fri, 10 Aug 2007 03:33:46 -0400 From: Marc Pignat Organization: HEVs To: =?iso-8859-15?q?Hans-J=FCrgen_Koch?= Subject: Re: [PATCH] at91 pm: Compilation fix for at91sam926x Date: Fri, 10 Aug 2007 09:33:45 +0200 User-Agent: KMail/1.9.5 Cc: linux-arm-kernel@lists.arm.linux.org.uk, "Ulf Samuelsson" , andrew@sanpeople.com, trivial@kernel.org, linux-kernel@vger.kernel.org, Andy Herzig References: <1186661447.6370.19.camel@leoh9-18574.nges.northgrum.com> <018a01c7dad3$10ca8190$dcc4af0a@atmel.com> <200708100912.35485.hjk@linutronix.de> In-Reply-To: <200708100912.35485.hjk@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200708100933.46235.marc.pignat@hevs.ch> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1638 Lines: 45 On Friday 10 August 2007 09:12, Hans-J?rgen Koch wrote: > Am Freitag 10 August 2007 00:15 schrieb Ulf Samuelsson: > > > > > > +#if defined(CONFIG_ARCH_AT91RM9200) > > > > at91_sys_write(AT91_SDRAMC_SRR, 1); /* > > > > self-refresh mode */ > > > > > Why don't use: > > > if (cpu_is_at91rm9200()) > > > at91_sys_write(AT91_SDRAMC_SRR, 1); > > > > What is the benefit? More readable. (see '#ifdefs are ugly' in Documentation/SubmittingPatches) > > Will the optimizer remove the code if the CPU is not the at91rm9200? Optimizer will remove that code if at91rm9200 support is not compiled and choose at runtime if the cpu support is compiled in. > > No, it won't. cpu_is_something() is intended for runtime decisions. > Remember that the purpose of this patch was to solve a compile time > issue (see subject). AT91_SDRAMC_SRR isn't defined properly for > non-9200 processors because they don't have that register. So we need > something like #ifdef to include this line only on 9200. Oops, I missed that problem, sorry... and what about this: #ifdef CONFIG_ARCH_AT91RM9200 #define sdram_lowpower_enable() at91_sys_write(AT91_SDRAMC_SRR, 1) #define sdram_lowpower_disable() at91_sys_write(AT91_SDRAMC_SRR, 0) #else #define sdram_lowpower_enable() #define sdram_lowpower_disable() #endif and using sdram_lowpower_{enable,disable}() when requiered? Regards Marc - 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/