diff options
authorviresh kumar <viresh.kumar@linaro.org>2014-03-14 12:10:55 +0530
committerMark Brown <broonie@kernel.org>2014-09-30 13:10:29 +0100
commit5c4e2425d94aa1545ce9d5feb9324ca85f62ef90 (patch)
parent6846e7822c4cab5a84672baace3b768c2d0db142 (diff)
cpufreq: arm_big_little: set 'physical_cluster' for each CPUv3.10/topic/tc2
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> (cherry picked from commit 8f3ba3d3257be80636ed15cc221d6a2efb6a6e82) Signed-off-by: Mark Brown <broonie@kernel.org>
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 076f25a59e00..eaee6e222207 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -456,9 +456,12 @@ static int bL_cpufreq_init(struct cpufreq_policy *policy)
cpufreq_frequency_table_get_attr(freq_table[cur_cluster], policy->cpu);
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;