diff options
author | viresh kumar <viresh.kumar@linaro.org> | 2014-03-14 02:40:55 -0400 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2014-03-18 21:18:39 -0400 |
commit | 8f3ba3d3257be80636ed15cc221d6a2efb6a6e82 (patch) | |
tree | 67137d27a65623294718742d3d8219712986a4aa /drivers/cpufreq | |
parent | 3b84d58d42d75025077f321997da402f0df67e59 (diff) |
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')
-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 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) | |||
446 | } | 446 | } |
447 | 447 | ||
448 | if (cur_cluster < MAX_CLUSTERS) { | 448 | if (cur_cluster < MAX_CLUSTERS) { |
449 | int cpu; | ||
450 | |||
449 | cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu)); | 451 | cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu)); |
450 | 452 | ||
451 | per_cpu(physical_cluster, policy->cpu) = cur_cluster; | 453 | for_each_cpu(cpu, policy->cpus) |
454 | per_cpu(physical_cluster, cpu) = cur_cluster; | ||
452 | } else { | 455 | } else { |
453 | /* Assumption: during init, we are always running on A15 */ | 456 | /* Assumption: during init, we are always running on A15 */ |
454 | per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER; | 457 | per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER; |