From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752412Ab3LBPbZ (ORCPT ); Mon, 2 Dec 2013 10:31:25 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:40528 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752298Ab3LBPbV (ORCPT ); Mon, 2 Dec 2013 10:31:21 -0500 Message-ID: <529CA6DD.2050108@linux.vnet.ibm.com> Date: Mon, 02 Dec 2013 20:57:25 +0530 From: Preeti U Murthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Thomas Gleixner CC: fweisbec@gmail.com, paul.gortmaker@windriver.com, paulus@samba.org, shangw@linux.vnet.ibm.com, rjw@sisk.pl, galak@kernel.crashing.org, benh@kernel.crashing.org, paulmck@linux.vnet.ibm.com, arnd@arndb.de, linux-pm@vger.kernel.org, rostedt@goodmis.org, michael@ellerman.id.au, john.stultz@linaro.org, chenhui.zhao@freescale.com, deepthi@linux.vnet.ibm.com, r58472@freescale.com, geoff@infradead.org, linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com, schwidefsky@de.ibm.com, svaidy@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH V4 6/9] cpuidle/ppc: Add basic infrastructure to enable the broadcast framework on ppc References: <20131129104010.651.23117.stgit@preeti.in.ibm.com> <20131129104303.651.40279.stgit@preeti.in.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13120215-5806-0000-0000-00002390F53F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, On 11/29/2013 05:28 PM, Thomas Gleixner wrote: > On Fri, 29 Nov 2013, Preeti U Murthy wrote: >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig >> index b44b52c..cafa788 100644 >> --- a/arch/powerpc/Kconfig >> +++ b/arch/powerpc/Kconfig >> @@ -129,6 +129,8 @@ config PPC >> select GENERIC_CMOS_UPDATE >> select GENERIC_TIME_VSYSCALL_OLD >> select GENERIC_CLOCKEVENTS >> + select GENERIC_CLOCKEVENTS_BROADCAST >> + select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > > What's the point of this config switch? It's nowhere used. When broadcast IPIs are to be sent, either the "broadcast" method associated with the local timers is used or an arch-specific method tick_broadcast() is invoked. For the latter be invoked, ARCH_HAS_TICK_BROADCAST config needs to be set. On PowerPC, the broadcast method is not associated with the local timer. Hence we invoke tick_broadcast(). This function has been added in [PATCH 2/9]. > >> +static int broadcast_set_next_event(unsigned long evt, >> + struct clock_event_device *dev) >> +{ >> + return 0; >> +} >> + >> +static void broadcast_set_mode(enum clock_event_mode mode, >> + struct clock_event_device *dev) >> +{ >> + if (mode != CLOCK_EVT_MODE_ONESHOT) >> + broadcast_set_next_event(DECREMENTER_MAX, dev); > > What's the point of calling an empty function? You are right, this should have remained a dummy function like broadcast_set_next_event() as per the design of this patchset. > >> +} >> + >> static void decrementer_set_mode(enum clock_event_mode mode, >> struct clock_event_device *dev) >> { >> @@ -840,6 +869,19 @@ static void register_decrementer_clockevent(int cpu) >> clockevents_register_device(dec); >> } >> >> +static void register_broadcast_clockevent(int cpu) >> +{ >> + struct clock_event_device *bc_evt = &bc_timer; >> + >> + *bc_evt = broadcast_clockevent; >> + bc_evt->cpumask = cpu_possible_mask; >> + >> + printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n", >> + bc_evt->name, bc_evt->mult, bc_evt->shift, cpu); >> + >> + clockevents_register_device(bc_evt); >> +} >> + >> static void __init init_decrementer_clockevent(void) >> { >> int cpu = smp_processor_id(); >> @@ -854,6 +896,19 @@ static void __init init_decrementer_clockevent(void) >> register_decrementer_clockevent(cpu); >> } >> >> +static void __init init_broadcast_clockevent(void) >> +{ >> + int cpu = smp_processor_id(); >> + >> + clockevents_calc_mult_shift(&broadcast_clockevent, ppc_tb_freq, 4); >> + >> + broadcast_clockevent.max_delta_ns = >> + clockevent_delta2ns(DECREMENTER_MAX, &broadcast_clockevent); >> + broadcast_clockevent.min_delta_ns = >> + clockevent_delta2ns(2, &broadcast_clockevent); > > clockevents_config() Right, I will change this to call clockevents_config(). I see that this needs to be done during the initialization of the decrementer as well. Will do the same. Thank you Regards Preeti U Murthy > > Thanks, > > tglx >