[PATCH 3.16 046/305] cpufreq: Fix GOV_LIMITS handling for the userspace governor

Ben Hutchings
2016-08-14T11:01:48Z

From: Sai Gurrappadi <sgurrappadi@nvidia.com>

commit e43e94c1eda76dabd686ddf6f7825f54d747b310 upstream.

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 storing the user requested frequency in a seperate variable.
The governor will then try to achieve this request on every GOV_LIMITS
change.

Fixes: d1922f02562f (cpufreq: Simplify userspace governor)
Signed-off-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/cpufreq/cpufreq_userspace.c | 43 ++++++++++++++++++++++++++++++++-----
1 file changed, 38 insertions(+), 5 deletions(-)

--- a/drivers/cpufreq/cpufreq_userspace.c
+++ b/drivers/cpufreq/cpufreq_userspace.c
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/slab.h>

static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
static DEFINE_MUTEX(userspace_mutex);
@@ -31,6 +32,7 @@ static DEFINE_MUTEX(userspace_mutex);
static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
{
int ret = -EINVAL;
+ unsigned int *setspeed = policy->governor_data;

pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);

@@ -38,6 +40,8 @@ static int cpufreq_set(struct cpufreq_po
if (!per_cpu(cpu_is_managed, policy->cpu))
goto err;

+ *setspeed = freq;
+
ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
err:
mutex_unlock(&userspace_mutex);
@@ -49,19 +53,45 @@ static ssize_t show_speed(struct cpufreq
return sprintf(buf, "%u\n", policy->cur);
}

+static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
+{
+ unsigned int *setspeed;
+
+ setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
+ if (!setspeed)
+ return -ENOMEM;
+
+ policy->governor_data = setspeed;
+ return 0;
+}
+
static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
unsigned int event)
{
+ unsigned int *setspeed = policy->governor_data;
unsigned int cpu = policy->cpu;
int rc = 0;

+ if (event == CPUFREQ_GOV_POLICY_INIT)
+ return cpufreq_userspace_policy_init(policy);
+
+ if (!setspeed)
+ return -EINVAL;
+
switch (event) {
+ case CPUFREQ_GOV_POLICY_EXIT:
+ mutex_lock(&userspace_mutex);
+ policy->governor_data = NULL;
+ kfree(setspeed);
+ mutex_unlock(&userspace_mutex);
+ break;
case CPUFREQ_GOV_START:
BUG_ON(!policy->cur);
pr_debug("started managing cpu %u\n", cpu);

mutex_lock(&userspace_mutex);
per_cpu(cpu_is_managed, cpu) = 1;
+ *setspeed = policy->cur;
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_STOP:
@@ -69,20 +99,23 @@ static int cpufreq_governor_userspace(st

mutex_lock(&userspace_mutex);
per_cpu(cpu_is_managed, cpu) = 0;
+ *setspeed = 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",
- cpu, policy->min, policy->max,
- policy->cur);
+ 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, *setspeed);

- if (policy->max < policy->cur)
+ if (policy->max < *setspeed)
__cpufreq_driver_target(policy, policy->max,
CPUFREQ_RELATION_H);
- else if (policy->min > policy->cur)
+ else if (policy->min > *setspeed)
__cpufreq_driver_target(policy, policy->min,
CPUFREQ_RELATION_L);
+ else
+ __cpufreq_driver_target(policy, *setspeed,
+ CPUFREQ_RELATION_L);
mutex_unlock(&userspace_mutex);
break;
}