From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jisheng Zhang Subject: Re: [PATCH 1/5] ARM: berlin: add SMP support Date: Tue, 3 Jun 2014 14:19:13 +0800 Message-ID: <20140603141913.710a1f7e@xhacker> References: <1401700866-24804-1-git-send-email-antoine.tenart@free-electrons.com> <1401700866-24804-2-git-send-email-antoine.tenart@free-electrons.com> <20140602094715.GG28090@lunn.ch> <20140602100048.GA12162@kwain> <20140602100332.GH28090@lunn.ch> <20140602102750.GB13681@kwain> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20140602102750.GB13681@kwain> Sender: linux-kernel-owner@vger.kernel.org To: Antoine =?UTF-8?B?VMOpbmFydA==?= Cc: Andrew Lunn , "sebastian.hesselbarth@gmail.com" , "thomas.petazzoni@free-electrons.com" , Jimmy Xu , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "alexandre.belloni@free-electrons.com" , "linux-arm-kernel@lists.infradead.org" List-Id: devicetree@vger.kernel.org Hi Andrew, Antoine,=20 On Mon, 2 Jun 2014 03:27:50 -0700 Antoine T=C3=A9nart wrote: > On Mon, Jun 02, 2014 at 12:03:32PM +0200, Andrew Lunn wrote: > > On Mon, Jun 02, 2014 at 12:00:48PM +0200, Antoine T=C3=A9nart wrote= : > > > Hi Andrew, > > >=20 > > > On Mon, Jun 02, 2014 at 11:47:15AM +0200, Andrew Lunn wrote: > > > > On Mon, Jun 02, 2014 at 11:21:02AM +0200, Antoine T=C3=A9nart w= rote: > > > > > + > > > > > +static inline void berlin_reset_cpu(unsigned int cpu) > > > > > +{ > > > > > + u32 val; > > > > > + > > > > > + val =3D readl(cpu_ctrl + CPU_RESET); > > > > > + val |=3D BIT(cpu_logical_map(cpu)); > > > > > + writel(val, cpu_ctrl + CPU_RESET); > > > > > +} > > > >=20 > > > > Is this performing a reset on the CPU, or is it taking it out o= f > > > > reset? > > > >=20 > > > > If you are going to implement CPU hotplug at some point, you ar= e going > > > > to want to be able to put the CPU into reset, i.e. power it off= , and > > > > take it out of reset, i.e. power it on and getting it running. = So it > > > > might help if we get these function names clear now. > > >=20 > > > It is performing a reset on the CPU. berlin_perform_reset_cpu() t= hen? > >=20 > > What happens if the CPU is powered off? Will a reset power it on? = Or > > are you assuming the boot loader has powered it on? >=20 > I actually don't have information about this. For now let's assume th= e > boot loader has powered on the CPUs. >=20 We don't support independently power off cpu on BG2 and BG2Q in linux k= ernel. So we can assume that bootloader has powered on the CPUs