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authorviresh kumar <viresh.kumar@linaro.org>2014-03-14 12:10:55 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-19 02:18:39 +0100
commit8f3ba3d3257be80636ed15cc221d6a2efb6a6e82 (patch)
tree67137d27a65623294718742d3d8219712986a4aa /drivers/cpufreq/arm_big_little.c
parent3b84d58d42d75025077f321997da402f0df67e59 (diff)
downloadleg-kernel-8f3ba3d3257be80636ed15cc221d6a2efb6a6e82.tar.gz
cpufreq: arm_big_little: set 'physical_cluster' for each CPU
We have a per-CPU variable for managing which cluster a CPU belongs to. Currently, physical_cluster is set for policy->cpu only which leads to the following on some SoC's: - There are two clusters: - Cluster 0 has four ARM Cortex A7 CPUs (slower ones): 0,1,2,3 - Cluster 1 has four ARM Cortex A15 CPUs (faster ones): 4,5,6,7 - CPUs are booted in order 0,1..7 and so initially policy->cpu for A7 cluster would be 0 and for A15 cluster would be 4. - Now CPU4 (i.e. A15_0) is hotplugged out and so policy->cpu for A15 cluster becomes 5 (i.e. A15_1). - But physical cluster is only set for CPU0 and CPU4 in ARM big LITTLE driver and isn't updated. - Now freq change request comes for A15 cluster and we would try to update freq of physical_cluster of CPU5, i.e. A15_1. And it is currently set to zero (default value of uninitialized global variables). - And so we actually try to change freq of A7 cluster instead of A15. - This also results in kernel crash as sometimes we might request freq above A7's limit and CPU may behave badly.. Fix this by initializing physical_cluster for all CPUs of a policy. Based on previous work by Xin Wang. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/arm_big_little.c')
-rw-r--r--drivers/cpufreq/arm_big_little.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 3d8707848035..bad2ed317ba2 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -446,9 +446,12 @@ static int bL_cpufreq_init(struct cpufreq_policy *policy)
}
if (cur_cluster < MAX_CLUSTERS) {
+ int cpu;
+
cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
- per_cpu(physical_cluster, policy->cpu) = cur_cluster;
+ for_each_cpu(cpu, policy->cpus)
+ per_cpu(physical_cluster, cpu) = cur_cluster;
} else {
/* Assumption: during init, we are always running on A15 */
per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;