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pm: device_runtime: Simplify mutex usage

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Assuming that pm_device_state_set is synchronous it is possible to
simplify the mutex usage. Now there are two places where the lock is
held, one in the worqueue handler and other in pm_device_request to
cover the synchronous path. It is no longer needed held the lock in the
pm_device_state_set callback and not needed to wait on the conditional
variable after set the state in the synchronous path.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
This commit is contained in:
Flavio Ceolin 2021-05-25 21:51:04 -07:00 • committed by Anas Nashif
commit 5c03d9643f
1 changed files with 13 additions and 10 deletions
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23
subsys/pm/device_runtime.c
View file

@ -24,9 +24,7 @@ static void device_pm_callback(const struct device *dev,
{
__ASSERT(retval == 0, "Device set power state failed");
(void)k_mutex_lock(&dev->pm->lock, K_FOREVER);
dev->pm->state = *state;
(void)k_mutex_unlock(&dev->pm->lock);
/*
* This function returns the number of woken threads on success. There
@ -40,8 +38,6 @@ static void pm_device_runtime_state_set(struct pm_device *pm)
const struct device *dev = pm->dev;
int ret = 0;
(void)k_mutex_lock(&dev->pm->lock, K_FOREVER);
switch (dev->pm->state) {
case PM_DEVICE_STATE_ACTIVE:
if ((dev->pm->usage == 0) && dev->pm->enable) {
@ -71,7 +67,7 @@ static void pm_device_runtime_state_set(struct pm_device *pm)
}
__ASSERT(ret == 0, "Set Power state error");
goto end;
return;
handler_out:
/*
@ -79,8 +75,6 @@ handler_out:
* is nothing we can do with this information. Just ignoring it.
*/
(void)k_condvar_broadcast(&dev->pm->condvar);
end:
(void)k_mutex_unlock(&dev->pm->lock);
}
static void pm_work_handler(struct k_work *work)
@ -88,7 +82,9 @@ static void pm_work_handler(struct k_work *work)
struct pm_device *pm = CONTAINER_OF(work,
struct pm_device, work);
(void)k_mutex_lock(&pm->lock, K_FOREVER);
pm_device_runtime_state_set(pm);
(void)k_mutex_unlock(&pm->lock);
}
static int pm_device_request(const struct device *dev,
@ -157,16 +153,23 @@ static int pm_device_request(const struct device *dev,
goto out_unlock;
}
while ((k_work_delayable_is_pending(&dev->pm->work)) ||
(dev->pm->state == PM_DEVICE_STATE_SUSPENDING) ||
(dev->pm->state == PM_DEVICE_STATE_RESUMING)) {
ret = k_condvar_wait(&dev->pm->condvar, &dev->pm->lock,
K_FOREVER);
if (ret != 0) {
break;
}
}
pm_device_runtime_state_set(dev->pm);
(void)k_mutex_unlock(&dev->pm->lock);
pm_device_wait(dev, K_FOREVER);
/*
* dev->pm->state was set in device_pm_callback(). As the device
* may not have been properly changed to the target_state or another
* thread we check it here before returning.
*/
(void)k_mutex_lock(&dev->pm->lock, K_FOREVER);
ret = target_state == dev->pm->state ? 0 : -EIO;
out_unlock: