cpufreq: Simplify __cpufreq_remove_dev()

__cpufreq_remove_dev() is called on multiple occasions: cpufreq_driver
unregister and cpu removals.

Current implementation of this routine is overly complex without much need. If
the cpu to be removed is the policy->cpu, we remove the policy first and add all
other cpus again from policy->cpus and then finally call __cpufreq_remove_dev()
again to remove the cpu to be deleted. Haahhhh..

There exist a simple solution to removal of a cpu:
- Simply use the old policy structure
- update its fields like: policy->cpu, etc.
- notify any users of cpufreq, which depend on changing policy->cpu

Hence this patch, which tries to implement the above theory. It is tested well
by myself on ARM big.LITTLE TC2 SoC, which has 5 cores (2 A15 and 3 A7). Both
A15's share same struct policy and all A7's share same policy structure.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index a55b88eaf96a..52be2d0c994a 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -93,7 +93,9 @@ struct cpufreq_policy {
         cpumask_var_t           related_cpus; /* CPUs with any coordination */
         unsigned int            shared_type; /* ANY or ALL affected CPUs
                                                 should set cpufreq */
-        unsigned int            cpu;    /* cpu nr of registered CPU */
+        unsigned int            cpu;    /* cpu nr of CPU managing this policy */
+        unsigned int            last_cpu; /* cpu nr of previous CPU that managed
+                                           * this policy */
         struct cpufreq_cpuinfo  cpuinfo;/* see above */
 
         unsigned int            min;    /* in kHz */
@@ -112,10 +114,11 @@ struct cpufreq_policy {
         struct completion       kobj_unregister;
 };
 
-#define CPUFREQ_ADJUST          (0)
-#define CPUFREQ_INCOMPATIBLE    (1)
-#define CPUFREQ_NOTIFY          (2)
-#define CPUFREQ_START           (3)
+#define CPUFREQ_ADJUST                  (0)
+#define CPUFREQ_INCOMPATIBLE            (1)
+#define CPUFREQ_NOTIFY                  (2)
+#define CPUFREQ_START                   (3)
+#define CPUFREQ_UPDATE_POLICY_CPU       (4)
 
 #define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
 #define CPUFREQ_SHARED_TYPE_HW   (1) /* HW does needed coordination */
@@ -405,6 +408,7 @@ extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
 
 void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table,
                                       unsigned int cpu);
+void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy);
 
 void cpufreq_frequency_table_put_attr(unsigned int cpu);
 #endif /* _LINUX_CPUFREQ_H */