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Subject[PATCH 4/4] PM / devfreq: Handle monitor start/stop in the devfreq core
Date
devfreq expects governors to call devfreq_monitor_start/stop()
in response to DEVFREQ_GOV_START/STOP events. Since the devfreq
core itself generates these events and invokes the governor's event
handler the start/stop of the load monitor can be done in the common
code.

Call devfreq_monitor_start/stop() when the governor reports a
successful handling of DEVFREQ_GOV_START/STOP and remove these
calls from the simpleondemand and tegra governors. Make
devfreq_monitor_start/stop() static since these functions are now
only used by the devfreq core. For better integration with the
callers the functions must now be called with devfreq->lock held.

Also stop manipulating the monitor workqueue directly, use
devfreq_monitor_start/stop() instead.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
drivers/devfreq/devfreq.c | 45 +++++++++++------------
drivers/devfreq/governor.h | 2 -
drivers/devfreq/governor_simpleondemand.c | 8 ----
drivers/devfreq/tegra-devfreq.c | 2 -
4 files changed, 22 insertions(+), 35 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index eb86461648d74..ac553c00f6790 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -404,14 +404,14 @@ static void devfreq_monitor(struct work_struct *work)
* devfreq_monitor_start() - Start load monitoring of devfreq instance
* @devfreq: the devfreq instance.
*
- * Helper function for starting devfreq device load monitoing. By
- * default delayed work based monitoring is supported. Function
- * to be called from governor in response to DEVFREQ_GOV_START
- * event when device is added to devfreq framework.
+ * Helper function for starting devfreq device load monitoring. By
+ * default delayed work based monitoring is supported. Must be called
+ * with devfreq->lock held.
*/
-void devfreq_monitor_start(struct devfreq *devfreq)
+static void devfreq_monitor_start(struct devfreq *devfreq)
{
- mutex_lock(&devfreq->lock);
+ WARN(!mutex_is_locked(&devfreq->lock),
+ "devfreq->lock must be held by the caller.\n");

if (devfreq->profile->polling_ms) {
INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
@@ -420,28 +420,28 @@ void devfreq_monitor_start(struct devfreq *devfreq)

devfreq->monitor_state = DEVFREQ_MONITOR_RUNNING;
}
-
- mutex_unlock(&devfreq->lock);
}
-EXPORT_SYMBOL(devfreq_monitor_start);

/**
* devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
* @devfreq: the devfreq instance.
*
- * Helper function to stop devfreq device load monitoing. Function
- * to be called from governor in response to DEVFREQ_GOV_STOP
- * event when device is removed from devfreq framework.
+ * Helper function to stop devfreq device load monitoring. Must be
+ * called with devfreq->lock held.
*/
-void devfreq_monitor_stop(struct devfreq *devfreq)
+static void devfreq_monitor_stop(struct devfreq *devfreq)
{
+ /* mutex must be held for symmetry with _start() */
+ WARN(!mutex_is_locked(&devfreq->lock),
+ "devfreq->lock must be held by the caller.\n");
+
+ mutex_unlock(&devfreq->lock);
cancel_delayed_work_sync(&devfreq->work);

mutex_lock(&devfreq->lock);
devfreq->monitor_state = DEVFREQ_MONITOR_STOPPED;
mutex_unlock(&devfreq->lock);
}
-EXPORT_SYMBOL(devfreq_monitor_stop);

/**
* devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
@@ -518,27 +518,22 @@ void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)

/* if new delay is zero, stop polling */
if (!new_delay) {
+ devfreq_monitor_stop(devfreq);
mutex_unlock(&devfreq->lock);
- cancel_delayed_work_sync(&devfreq->work);
- devfreq->monitor_state == DEVFREQ_MONITOR_STOPPED;
return;
}

/* if current delay is zero, start polling with new delay */
if (!cur_delay) {
- queue_delayed_work(devfreq_wq, &devfreq->work,
- msecs_to_jiffies(devfreq->profile->polling_ms));
+ devfreq_monitor_start(devfreq);
goto out;
}

/* if current delay is greater than new delay, restart polling */
if (cur_delay > new_delay) {
- mutex_unlock(&devfreq->lock);
- cancel_delayed_work_sync(&devfreq->work);
- mutex_lock(&devfreq->lock);
+ devfreq_monitor_stop(devfreq);
if (devfreq->monitor_state != DEVFREQ_MONITOR_SUSPENDED)
- queue_delayed_work(devfreq_wq, &devfreq->work,
- msecs_to_jiffies(devfreq->profile->polling_ms));
+ devfreq_monitor_start(devfreq);
}
out:
mutex_unlock(&devfreq->lock);
@@ -601,6 +596,8 @@ static int devfreq_governor_start(struct devfreq *devfreq)
return err;
}

+ devfreq_monitor_start(devfreq);
+
return 0;
}

@@ -624,6 +621,8 @@ static int devfreq_governor_stop(struct devfreq *devfreq)
return err;
}

+ devfreq_monitor_stop(devfreq);
+
return 0;
}

diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index d136792c0cc91..47efe747b6f79 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -57,8 +57,6 @@ struct devfreq_governor {
unsigned int event, void *data);
};

-extern void devfreq_monitor_start(struct devfreq *devfreq);
-extern void devfreq_monitor_stop(struct devfreq *devfreq);
extern void devfreq_interval_update(struct devfreq *devfreq,
unsigned int *delay);

diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
index 52eb0c734b312..e0f0944a9c7aa 100644
--- a/drivers/devfreq/governor_simpleondemand.c
+++ b/drivers/devfreq/governor_simpleondemand.c
@@ -91,14 +91,6 @@ static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
unsigned int event, void *data)
{
switch (event) {
- case DEVFREQ_GOV_START:
- devfreq_monitor_start(devfreq);
- break;
-
- case DEVFREQ_GOV_STOP:
- devfreq_monitor_stop(devfreq);
- break;
-
case DEVFREQ_GOV_INTERVAL:
devfreq_interval_update(devfreq, (unsigned int *)data);
break;
diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
index 79efa1e51bd06..515fb852dbad6 100644
--- a/drivers/devfreq/tegra-devfreq.c
+++ b/drivers/devfreq/tegra-devfreq.c
@@ -580,13 +580,11 @@ static int tegra_governor_event_handler(struct devfreq *devfreq,

switch (event) {
case DEVFREQ_GOV_START:
- devfreq_monitor_start(devfreq);
tegra_actmon_enable_interrupts(tegra);
break;

case DEVFREQ_GOV_STOP:
tegra_actmon_disable_interrupts(tegra);
- devfreq_monitor_stop(devfreq);
break;

case DEVFREQ_GOV_SUSPEND:
--
2.20.1.791.gb4d0f1c61a-goog
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