Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754875AbbDOOq4 (ORCPT ); Wed, 15 Apr 2015 10:46:56 -0400 Received: from foss.arm.com ([217.140.101.70]:36156 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752287AbbDOOqr (ORCPT ); Wed, 15 Apr 2015 10:46:47 -0400 Date: Wed, 15 Apr 2015 15:46:32 +0100 From: Catalin Marinas To: Arnd Bergmann Cc: linux-arm-kernel@lists.infradead.org, Mark Rutland , "devicetree@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , Kumar Gala , Will Deacon , "linux-kernel@vger.kernel.org" , "arm@kernel.org" , Abhimanyu Kapur Subject: Re: [RFC PATCH 5/5] arm64: qcom: add cpu operations Message-ID: <20150415144630.GA22741@localhost> References: <1428601031-5366-1-git-send-email-galak@codeaurora.org> <1428601031-5366-6-git-send-email-galak@codeaurora.org> <20150414162953.GL28709@leverpostej> <2167031.4Enm47D6vo@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2167031.4Enm47D6vo@wuerfel> 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 Content-Length: 1856 Lines: 46 On Tue, Apr 14, 2015 at 10:51:40PM +0200, Arnd Bergmann wrote: > On Tuesday 14 April 2015 17:29:53 Mark Rutland wrote: > > > +static int msm_cpu_boot(unsigned int cpu) > > > +{ > > > + int ret = 0; > > > + > > > + if (per_cpu(cold_boot_done, cpu) == false) { > > > + ret = msm_unclamp_secondary_arm_cpu(cpu); > > > + if (ret) > > > + return ret; > > > + per_cpu(cold_boot_done, cpu) = true; > > > + } > > > + return secondary_pen_release(cpu); > > > +} > > > > Ah, so cold_boot_done is for pseudo-hotplug. Absolute NAK to that. > > > > The only thing this gives you over spin-table is one-time powering up of > > the CPUs that can be performed prior to entry to Linux. If you do that, > > you can trivially share the spin-table code by setting each CPU's > > enable-method to "spin-table". > > > > That won't give you cpuidle or actual hotplug. For those you'll need > > PSCI. > > Maybe a way out for the broken firmware is to have a custom boot wrapper > that gets distributed separately and that uses the normal spin-table > API. We've done similar things on arch/arm/mach-sunxi for boot loaders > that are just too different from what we expect. As a starting point, we actually have one that can do both spin table and PSCI ;) (three-clause BSD license): git://git.kernel.org/pub/scm/linux/kernel/git/mark/boot-wrapper-aarch64.git Its primary goal is to create an ELF file that can be loaded on a software model but there isn't anything that prevents you from generating a kernel Image-like header. -- 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/