From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: [PATCH] OMAP2+: CPUfreq: Allow the CPU scaling when secondary CPUs are offline. Date: Thu, 02 Jun 2011 20:23:57 +0530 Message-ID: <4DE7A405.9030602@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from na3sys009aog103.obsmtp.com ([74.125.149.71]:41963 "EHLO na3sys009aog103.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752608Ab1FBOyE (ORCPT ); Thu, 2 Jun 2011 10:54:04 -0400 Received: by yxm8 with SMTP id 8so464073yxm.26 for ; Thu, 02 Jun 2011 07:54:02 -0700 (PDT) Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: l-o Cc: Kevin Hilman Missed Kevin in cc. :( Sorry about that. -------- Original Message -------- Subject: [PATCH] OMAP2+: CPUfreq: Allow the CPU scaling when secondary CPUs are offline. Date: Thu, 2 Jun 2011 20:21:10 +0530 From: Santosh Shilimkar To: CC: Santosh Shilimkar Current OMAP2PLUS CPUfreq tagret() functions returns when all the CPU's are not online. This will break DVFS when secondary CPUs are offlined. The intention of that check was just avoid CPU frequency change during the window when CPU becomes online but it's cpufreq_init is not done yet. Fix the check accordingly. Thanks for Nishant Menon for reporting it. Signed-off-by: Santosh Shilimkar Reported-by: Nishanth Menon Tested-by: Vishwanath BS --- There were some question of making the variable atomic etc in an internal discussion. After some thinking, I realised there is no need of that since this is just a counter which maintains the count for online_cpus = cpufreq_init_cpus. arch/arm/mach-omap2/omap2plus-cpufreq.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-) diff --git a/arch/arm/mach-omap2/omap2plus-cpufreq.c b/arch/arm/mach-omap2/omap2plus-cpufreq.c index 33a91ec..909bfcb 100644 --- a/arch/arm/mach-omap2/omap2plus-cpufreq.c +++ b/arch/arm/mach-omap2/omap2plus-cpufreq.c @@ -44,6 +44,7 @@ static struct cpufreq_frequency_table *freq_table; static struct clk *mpu_clk; static char *mpu_clk_name; static struct device *mpu_dev; +static int cpus_initialized; static int omap_verify_speed(struct cpufreq_policy *policy) { @@ -82,7 +83,7 @@ static int omap_target(struct cpufreq_policy *policy, struct cpufreq_freqs freqs; /* Changes not allowed until all CPUs are online */ - if (is_smp() && (num_online_cpus() < NR_CPUS)) + if (is_smp() && (cpus_initialized < num_online_cpus())) return ret; /* Ensure desired rate is within allowed range. Some govenors @@ -194,6 +195,8 @@ static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy) policy->shared_type = CPUFREQ_SHARED_TYPE_ANY; cpumask_or(cpumask, cpumask_of(policy->cpu), cpumask); cpumask_copy(policy->cpus, cpumask); + cpus_initialized++; + smp_wmb(); } /* FIXME: what's the actual transition time? */ @@ -206,6 +209,10 @@ static int omap_cpu_exit(struct cpufreq_policy *policy) { clk_exit_cpufreq_table(&freq_table); clk_put(mpu_clk); + if (is_smp()) { + cpus_initialized--; + smp_wmb(); + } return 0; } -- 1.6.0.4