2014-11-07 13:43:25

by Yadwinder Singh Brar

Subject: [PATCH v2] thermal: cpu_cooling: Update always cpufreq policy with thermal constraints

Existing code updates cupfreq policy only while executing
cpufreq_apply_cooling() function (i.e. when notify_device != NOTIFY_INVALID).
It doesn't apply constraints when cpufreq policy update happens from any other
place but it should update the cpufreq policy with thermal constraints every
time when there is a cpufreq policy update, to keep state of
cpufreq_cooling_device and max_feq of cpufreq policy in sync. For instance
while resuming cpufreq updates cpufreq_policy and it restores default
policy->usr_policy values irrespective of cooling device's cpufreq_state since
notification gets missed because (notify_device == NOTIFY_INVALID).
Another problem, is that userspace is able to change max_freq irrespective of
cooling device's state, as notification gets missed.

This patch modifies code to maintain a global cpufreq_dev_list and applies
constraints of all matching cooling devices for policy's cpu when there is any
policy update(ends up applying the lowest max_freq among the matching cpu
cooling devices).

This patch also removes redundant check (max_freq > policy->user_policy.max),
as cpufreq framework takes care of user_policy constraints already where ever
required, otherwise its causing an issue while increasing max_freq in normal
scenerio as it restores max_freq with policy->user_policy.max which is old
(smaller) value.

Signed-off-by: Yadwinder Singh Brar <[email protected]>
---

changes since v1:
- Updated commit message as suggested by Eduardo Valentin
- fixed an issue in incresing value of scaling_max_freq from sysfs after
decreasing it once in normal thermal conditions also.

---
drivers/thermal/cpu_cooling.c | 37 +++++++++++++++++++++----------------
1 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 1ab0018..ad09e51 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -50,15 +50,14 @@ struct cpufreq_cooling_device {
unsigned int cpufreq_state;
unsigned int cpufreq_val;
struct cpumask allowed_cpus;
+ struct list_head node;
};
static DEFINE_IDR(cpufreq_idr);
static DEFINE_MUTEX(cooling_cpufreq_lock);

static unsigned int cpufreq_dev_count;

-/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
-#define NOTIFY_INVALID NULL
-static struct cpufreq_cooling_device *notify_device;
+static LIST_HEAD(cpufreq_dev_list);

/**
* get_idr - function to get a unique id.
@@ -287,15 +286,12 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,

cpufreq_device->cpufreq_state = cooling_state;
cpufreq_device->cpufreq_val = clip_freq;
- notify_device = cpufreq_device;

for_each_cpu(cpuid, mask) {
if (is_cpufreq_valid(cpuid))
cpufreq_update_policy(cpuid);
}

- notify_device = NOTIFY_INVALID;
-
return 0;
}

@@ -316,21 +312,28 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
{
struct cpufreq_policy *policy = data;
unsigned long max_freq = 0;
+ struct cpufreq_cooling_device *cpufreq_dev;

- if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
+ if (event != CPUFREQ_ADJUST)
return 0;

- if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
- max_freq = notify_device->cpufreq_val;
- else
- return 0;
+ mutex_lock(&cooling_cpufreq_lock);
+ list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
+ if (!cpumask_test_cpu(policy->cpu,
+ &cpufreq_dev->allowed_cpus))
+ continue;
+
+ if (!cpufreq_dev->cpufreq_val)
+ cpufreq_dev->cpufreq_val = get_cpu_frequency(
+ cpumask_any(&cpufreq_dev->allowed_cpus),
+ cpufreq_dev->cpufreq_state);

- /* Never exceed user_policy.max */
- if (max_freq > policy->user_policy.max)
- max_freq = policy->user_policy.max;
+ max_freq = cpufreq_dev->cpufreq_val;

- if (policy->max != max_freq)
- cpufreq_verify_within_limits(policy, 0, max_freq);
+ if (policy->max != max_freq)
+ cpufreq_verify_within_limits(policy, 0, max_freq);
+ }
+ mutex_unlock(&cooling_cpufreq_lock);

return 0;
}
@@ -486,6 +489,7 @@ __cpufreq_cooling_register(struct device_node *np,
cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
CPUFREQ_POLICY_NOTIFIER);
cpufreq_dev_count++;
+ list_add(&cpufreq_dev->node, &cpufreq_dev_list);

mutex_unlock(&cooling_cpufreq_lock);

@@ -549,6 +553,7 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)

cpufreq_dev = cdev->devdata;
mutex_lock(&cooling_cpufreq_lock);
+ list_del(&cpufreq_dev->node);
cpufreq_dev_count--;

/* Unregister the notifier for the last cpufreq cooling device */
--
1.7.0.4