From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp09.in.ibm.com (e28smtp09.in.ibm.com [122.248.162.9]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 0028C1A0127 for ; Thu, 11 Sep 2014 20:14:32 +1000 (EST) Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 11 Sep 2014 15:44:26 +0530 Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 6B15F394004C for ; Thu, 11 Sep 2014 15:44:22 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay03.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id s8BAGggQ61604008 for ; Thu, 11 Sep 2014 15:46:42 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s8BAEK2L008824 for ; Thu, 11 Sep 2014 15:44:21 +0530 From: Shilpasri G Bhat To: viresh.kumar@linaro.org, benh@kernel.crashing.org Subject: [PATCH v3] cpufreq: powernv: Set the cpus to nominal frequency during reboot/kexec Date: Thu, 11 Sep 2014 15:43:43 +0530 Message-Id: <1410430423-1246-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> Cc: linux-pm@vger.kernel.org, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, David.Laight@ACULAB.COM, Shilpasri G Bhat , preeti@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This patch ensures the cpus to kexec/reboot at nominal frequency. Nominal frequency is the highest cpu frequency on PowerPC at which the cores can run without getting throttled. If the host kernel had set the cpus to a low pstate and then it kexecs/reboots to a cpufreq disabled kernel it would cause the target kernel to perform poorly. It will also increase the boot up time of the target kernel. So set the cpus to high pstate, in this case to nominal frequency before rebooting to avoid such scenarios. The reboot notifier will set the cpus to nominal frequncy. Signed-off-by: Shilpasri G Bhat Suggested-by: Viresh Kumar Reviewed-by: Preeti U Murthy --- Changes v2->v3: We return EBUSY when cpufreq governor tries to change the frequency after rebooting is set to true. This results in console being flushed with error messages indicating failed attempts to change the frequency. So instead of returning EBUSY we return 0 to stop the governor from changing the frequency without alerting a failure to do the same on reboot, as this is not an errorneaos condition. Changes v1->v2: Invoke .target() driver callback to set the cpus to nominal frequency in reboot notifier, instead of calling cpufreq_suspend() as suggested by Viresh Kumar. Modified the commit message. drivers/cpufreq/powernv-cpufreq.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index 379c083..f772a55 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -35,6 +36,7 @@ #define POWERNV_MAX_PSTATES 256 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1]; +static bool rebooting; /* * Note: The set of pstates consists of contiguous integers, the @@ -284,6 +286,15 @@ static void set_pstate(void *freq_data) } /* + * get_nominal_index: Returns the index corresponding to the nominal + * pstate in the cpufreq table + */ +static inline unsigned int get_nominal_index(void) +{ + return powernv_pstate_info.max - powernv_pstate_info.nominal; +} + +/* * powernv_cpufreq_target_index: Sets the frequency corresponding to * the cpufreq table entry indexed by new_index on the cpus in the * mask policy->cpus @@ -293,6 +304,9 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy, { struct powernv_smp_call_data freq_data; + if (unlikely(rebooting) && new_index != get_nominal_index()) + return 0; + freq_data.pstate_id = powernv_freqs[new_index].driver_data; /* @@ -317,6 +331,25 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy) return cpufreq_table_validate_and_show(policy, powernv_freqs); } +static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb, + unsigned long action, void *unused) +{ + int cpu; + struct cpufreq_policy cpu_policy; + + rebooting = true; + for_each_online_cpu(cpu) { + cpufreq_get_policy(&cpu_policy, cpu); + powernv_cpufreq_target_index(&cpu_policy, get_nominal_index()); + } + + return NOTIFY_DONE; +} + +static struct notifier_block powernv_cpufreq_reboot_nb = { + .notifier_call = powernv_cpufreq_reboot_notifier, +}; + static struct cpufreq_driver powernv_cpufreq_driver = { .name = "powernv-cpufreq", .flags = CPUFREQ_CONST_LOOPS, @@ -342,12 +375,14 @@ static int __init powernv_cpufreq_init(void) return rc; } + register_reboot_notifier(&powernv_cpufreq_reboot_nb); return cpufreq_register_driver(&powernv_cpufreq_driver); } module_init(powernv_cpufreq_init); static void __exit powernv_cpufreq_exit(void) { + unregister_reboot_notifier(&powernv_cpufreq_reboot_nb); cpufreq_unregister_driver(&powernv_cpufreq_driver); } module_exit(powernv_cpufreq_exit); -- 1.9.3