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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)
treec21583aabb3edc508d3ad66eb47631be0188819d /drivers/pwm
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>
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