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author | viresh kumar <viresh.kumar@linaro.org> | 2014-03-14 12:10:55 +0530 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-03-19 02:18:39 +0100 |
commit | 8f3ba3d3257be80636ed15cc221d6a2efb6a6e82 (patch) | |
tree | 67137d27a65623294718742d3d8219712986a4aa /drivers | |
parent | 3b84d58d42d75025077f321997da402f0df67e59 (diff) | |
download | op-kernel-dev-8f3ba3d3257be80636ed15cc221d6a2efb6a6e82.zip op-kernel-dev-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')
-rw-r--r-- | drivers/cpufreq/arm_big_little.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c index 3d87078..bad2ed3 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; |