Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757398Ab0LBQ2z (ORCPT ); Thu, 2 Dec 2010 11:28:55 -0500 Received: from service87.mimecast.com ([94.185.240.25]:42475 "HELO service87.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752744Ab0LBQ2y convert rfc822-to-8bit (ORCPT ); Thu, 2 Dec 2010 11:28:54 -0500 Subject: Re: [PATCH 1/8] ARM: SCU: Add common routines for secondary CPU bootup From: Catalin Marinas To: Russell King - ARM Linux Cc: Anton Vorontsov , Kukjin Kim , Srinidhi Kasagar , Tony Lindgren , Jamie Iles , Colin Cross , linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Uwe =?ISO-8859-1?Q?Kleine-K=F6nig?= , linux-tegra@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org In-Reply-To: <20101202152428.GD10461@n2100.arm.linux.org.uk> References: <20101130171626.GA6165@oksana.dev.rtsoft.ru> <20101130171658.GA24034@oksana.dev.rtsoft.ru> <20101130233204.GB14383@n2100.arm.linux.org.uk> <20101201002527.GC14383@n2100.arm.linux.org.uk> <20101202152428.GD10461@n2100.arm.linux.org.uk> Organization: ARM Limited Date: Thu, 02 Dec 2010 16:28:40 +0000 Message-ID: <1291307320.11271.51.camel@e102109-lin.cambridge.arm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 X-OriginalArrivalTime: 02 Dec 2010 16:28:41.0875 (UTC) FILETIME=[FB680630:01CB923D] X-MC-Unique: 110120216284606901 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2105 Lines: 47 On Thu, 2010-12-02 at 15:24 +0000, Russell King - ARM Linux wrote: > On Thu, Dec 02, 2010 at 03:19:05PM +0000, Catalin Marinas wrote: > > On 1 December 2010 00:25, Russell King - ARM Linux > > wrote: > > > On Tue, Nov 30, 2010 at 11:32:04PM +0000, Russell King - ARM Linux wrote: > > >> Note that I'll go with factoring this out into arch/arm/kernel/smp_scu.c > > >> for the time being, but I'm not convinced about the other parts yet. > > > > > > IOW, something like the attached. I've gone a little further and removed > > > the now unnecessary scu_enable() and scu_get_core_count() global functions, > > > making scu_enable() static, and eliminating scu_get_core_count() entirely. > > > > There is some benefit in leaving get_core_count() in the platform > > code. For example, the SCU on Cortex-A15 doesn't expose the core count > > register and we have to get it from somewhere else (for now from some > > L2 cache controller register but in the future it may be hardcoded, > > passed via FDT or simply trying to boot maxcpus). > > I notice that there's no way to tell what revision of SCU is implemented > on _any_ mpcore platform. C-A15 doesn't have any SCU registers exposed (and it's enabled by default). > In light of that, I think there's no point what so ever trying to > consolidate this code - even the control register bits vary in > unpredictable ways between different MPcore implementations. The SCU is part of the core TRM, so I don't expect it to be the same across various MP cores (and A15 is an example). You may want to consolidate functions like scu_prepare_cpus (maybe call it smp_prepare_cpus) and something that calls set_cpu_possible() but with platform callbacks for getting the number of calls and initialising the SMP (SCU for most platforms). Whether this is worth, I don't know. -- Catalin -- 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/