cpufreq: use last policy after online for drivers with ->setpolicy

For cpufreq drivers which use setpolicy interface, after offline->online
the policy is set to default. This can be reproduced by setting the
default policy of intel_pstate or longrun to ondemand and then change to
"performance". After offline and online, the setpolicy will be called with
the policy=ondemand.

For drivers using governors this condition is handled by storing
last_governor, during offline and restoring during online. The same should
be done for drivers using setpolicy interface. Storing last_policy during
offline and restoring during online.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 11 insertions, 4 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a83c995a62df..8412ce5f93a7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -976,10 +976,14 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy)
 
         new_policy.governor = gov;
 
-        /* Use the default policy if its valid. */
-        if (cpufreq_driver->setpolicy)
-                cpufreq_parse_governor(gov->name, &new_policy.policy, NULL);
-
+        /* Use the default policy if there is no last_policy. */
+        if (cpufreq_driver->setpolicy) {
+                if (policy->last_policy)
+                        new_policy.policy = policy->last_policy;
+                else
+                        cpufreq_parse_governor(gov->name, &new_policy.policy,
+                                               NULL);
+        }
         /* set default policy */
         return cpufreq_set_policy(policy, &new_policy);
 }
@@ -1330,6 +1334,8 @@ static void cpufreq_offline_prepare(unsigned int cpu)
                 if (has_target())
                         strncpy(policy->last_governor, policy->governor->name,
                                 CPUFREQ_NAME_LEN);
+                else
+                        policy->last_policy = policy->policy;
         } else if (cpu == policy->cpu) {
                 /* Nominate new CPU */
                 policy->cpu = cpumask_any(policy->cpus);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index ef4c5b1a860f..177c7680c1a8 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -77,6 +77,7 @@ struct cpufreq_policy {
         unsigned int            suspend_freq; /* freq to set during suspend */
 
         unsigned int            policy; /* see above */
+        unsigned int            last_policy; /* policy before unplug */
         struct cpufreq_governor *governor; /* see below */
         void                    *governor_data;
         bool                    governor_enabled; /* governor start/stop flag */