cpufreq: Fix GOV_LIMITS handling for the userspace governor

Resending without the copyright headed appended..sorry!

-Sai

=======

Currently, the userspace governor only updates frequency on GOV_LIMITS if policy->cur falls outside policy->{min/max}. However, it is also necessary to update current frequency on GOV_LIMITS to match the user requested value if it can be achieved within the new policy->{max/min}.

This was previously the behaviour in the governor until commit d1922f0 ("cpufreq: Simplify userspace governor") which incorrectly assumed that policy->cur == user requested frequency via scaling_setspeed. This won't be true if the user requested frequency falls outside policy->{min/max}.
Ex: a temporary thermal cap throttled the user requested frequency.

Fix this by doing a partial revert of commit d1922f0 to bring back the per-cpu cpu_set_freq variable that stores the user requested frequency. The governor will then try to achieve this request on every GOV_LIMITS.

Signed-off-by Sai Gurrappadi <[email protected]>

---

 drivers/cpufreq/cpufreq_userspace.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

drivers/cpufreq/cpufreq_userspace.c +4 -0

index 4d16f45..ae03ba7 100644
@@ -18,6 +18,8 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 
+static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
+							userspace */
 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
 static DEFINE_MUTEX(userspace_mutex);
 

@@ -38,6 +40,8 @@ static int cpufreq_set(struct cpufreq_policy *policy,
 unsigned int freq)
 	if (!per_cpu(cpu_is_managed, policy->cpu))
 		goto err;
 
+	per_cpu(cpu_set_freq, policy->cpu) = freq;
+
 	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  err:

drivers/cpufreq/cpufreq_userspace.c +1 -0

 	mutex_unlock(&userspace_mutex);

@@ -62,6 +66,7 @@ static int cpufreq_governor_userspace(struct cpufreq_policy
 *policy,
 
 		mutex_lock(&userspace_mutex);
 		per_cpu(cpu_is_managed, cpu) = 1;
+		per_cpu(cpu_set_freq, cpu) = policy->cur;
 		mutex_unlock(&userspace_mutex);
 		break;

drivers/cpufreq/cpufreq_userspace.c +11 -4

 	case CPUFREQ_GOV_STOP:

@@ -69,20 +74,27 @@ static int cpufreq_governor_userspace(struct
 cpufreq_policy *policy,
 
 		mutex_lock(&userspace_mutex);
 		per_cpu(cpu_is_managed, cpu) = 0;
+		per_cpu(cpu_set_freq, cpu) = 0;
 		mutex_unlock(&userspace_mutex);
 		break;
 	case CPUFREQ_GOV_LIMITS:
 		mutex_lock(&userspace_mutex);
-		pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz\n",
+		pr_debug("limit event for cpu %u: %u - %u kHz, "
+			"currently %u kHz, last set to %u kHz\n",
 			cpu, policy->min, policy->max,
-			policy->cur);
+			policy->cur, per_cpu(cpu_set_freq, cpu));
 
-		if (policy->max < policy->cur)
+		if (policy->max < per_cpu(cpu_set_freq, cpu)) {
 			__cpufreq_driver_target(policy, policy->max,
 						CPUFREQ_RELATION_H);
-		else if (policy->min > policy->cur)
+		} else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
 			__cpufreq_driver_target(policy, policy->min,
 						CPUFREQ_RELATION_L);
+		} else {
+			__cpufreq_driver_target(policy,
+						per_cpu(cpu_set_freq, cpu),
+						CPUFREQ_RELATION_L);
+		}
 		mutex_unlock(&userspace_mutex);
 		break;

}
-- 2.1.4

Quoted 5 lines · Sai Gurrappadi

Resending without the copyright headed appended..sorry!

-Sai

=======

:)

For your information, this isn't the right place to add text which shouldn't be committed.

Quoted 3 lines

Signed-off-by Sai Gurrappadi <[email protected]>

---

Rather do it here and git am will automatically drop that while applying the patch.

Quoted 2 lines

 drivers/cpufreq/cpufreq_userspace.c | 20 ++++++++++++++++----