From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
The code to handle the SMART_SUSPEND driver PM flag is hard to follow
and somewhat inconsistent with respect to devices without middle-layer
(subsystem) callbacks.
Namely, for those devices the core takes the role of a middle layer
in providing the expected ordering of execution of callbacks (under
the assumption that the drivers setting SMART_SUSPEND can reuse their
PM-runtime callbacks directly for system-wide suspend). To that end,
it prevents driver ->suspend_late and ->suspend_noirq callbacks from
being executed for devices that are still runtime-suspended in
__device_suspend_late(), because running the same callback funtion
that was previously run by PM-runtime for them may be invalid.
However, it does that only for devices without any middle-layer
callbacks for the late/noirq/early suspend/resume phases even
though it would be simpler and more consistent to skip the
driver-lavel callbacks for all devices with SMART_SUSPEND set
that are runtime-suspended in __device_suspend_late().
Simplify the code in accordance with the above observation.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
No changes from the first iteration.
---
drivers/base/power/main.c | 118 +++++++++++++++-------------------------------
1 file changed, 39 insertions(+), 79 deletions(-)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index fdd508a78ffd..5d0225573bbe 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -561,24 +561,6 @@ static void dpm_watchdog_clear(struct dpm_watchdog *wd)
/*------------------------- Resume routines -------------------------*/
-/**
- * suspend_event - Return a "suspend" message for given "resume" one.
- * @resume_msg: PM message representing a system-wide resume transition.
- */
-static pm_message_t suspend_event(pm_message_t resume_msg)
-{
- switch (resume_msg.event) {
- case PM_EVENT_RESUME:
- return PMSG_SUSPEND;
- case PM_EVENT_THAW:
- case PM_EVENT_RESTORE:
- return PMSG_FREEZE;
- case PM_EVENT_RECOVER:
- return PMSG_HIBERNATE;
- }
- return PMSG_ON;
-}
-
/**
* dev_pm_may_skip_resume - System-wide device resume optimization check.
* @dev: Target device.
@@ -656,37 +638,36 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn
if (!dpm_wait_for_superior(dev, async))
goto Out;
- skip_resume = dev_pm_may_skip_resume(dev);
-
callback = dpm_subsys_resume_noirq_cb(dev, state, &info);
- if (callback)
+ if (callback) {
+ skip_resume = false;
goto Run;
+ }
+ skip_resume = dev_pm_may_skip_resume(dev);
if (skip_resume)
goto Skip;
- if (dev_pm_smart_suspend_and_suspended(dev)) {
- pm_message_t suspend_msg = suspend_event(state);
-
- /*
- * If "freeze" callbacks have been skipped during a transition
- * related to hibernation, the subsequent "thaw" callbacks must
- * be skipped too or bad things may happen. Otherwise, resume
- * callbacks are going to be run for the device, so its runtime
- * PM status must be changed to reflect the new state after the
- * transition under way.
- */
- if (!dpm_subsys_suspend_late_cb(dev, suspend_msg, NULL) &&
- !dpm_subsys_suspend_noirq_cb(dev, suspend_msg, NULL)) {
- if (state.event == PM_EVENT_THAW) {
- skip_resume = true;
- goto Skip;
- } else {
- pm_runtime_set_active(dev);
- }
- }
+ /*
+ * If "freeze" driver callbacks have been skipped during hibernation,
+ * because the device was runtime-suspended in __device_suspend_late(),
+ * the corresponding "thaw" callbacks must be skipped too, because
+ * running them for a runtime-suspended device may not be valid.
+ */
+ if (dev_pm_smart_suspend_and_suspended(dev) &&
+ state.event == PM_EVENT_THAW) {
+ skip_resume = true;
+ goto Skip;
}
+ /*
+ * The device is going to be resumed, so set its PM-runtime status to
+ * "active", but do that only if DPM_FLAG_SMART_SUSPEND is set to avoid
+ * confusing drivers that don't use it.
+ */
+ if (dev_pm_smart_suspend_and_suspended(dev))
+ pm_runtime_set_active(dev);
+
if (dev->driver && dev->driver->pm) {
info = "noirq driver ";
callback = pm_noirq_op(dev->driver->pm, state);
@@ -1274,32 +1255,6 @@ static pm_callback_t dpm_subsys_suspend_noirq_cb(struct device *dev,
return callback;
}
-static bool device_must_resume(struct device *dev, pm_message_t state,
- bool no_subsys_suspend_noirq)
-{
- pm_message_t resume_msg = resume_event(state);
-
- /*
- * If all of the device driver's "noirq", "late" and "early" callbacks
- * are invoked directly by the core, the decision to allow the device to
- * stay in suspend can be based on its current runtime PM status and its
- * wakeup settings.
- */
- if (no_subsys_suspend_noirq &&
- !dpm_subsys_suspend_late_cb(dev, state, NULL) &&
- !dpm_subsys_resume_early_cb(dev, resume_msg, NULL) &&
- !dpm_subsys_resume_noirq_cb(dev, resume_msg, NULL))
- return !pm_runtime_status_suspended(dev) &&
- (resume_msg.event != PM_EVENT_RESUME ||
- (device_can_wakeup(dev) && !device_may_wakeup(dev)));
-
- /*
- * The only safe strategy here is to require that if the device may not
- * be left in suspend, resume callbacks must be invoked for it.
- */
- return !dev->power.may_skip_resume;
-}
-
/**
* __device_suspend_noirq - Execute a "noirq suspend" callback for given device.
* @dev: Device to handle.
@@ -1313,7 +1268,6 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
{
pm_callback_t callback;
const char *info;
- bool no_subsys_cb = false;
int error = 0;
TRACE_DEVICE(dev);
@@ -1331,9 +1285,7 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
if (callback)
goto Run;
- no_subsys_cb = !dpm_subsys_suspend_late_cb(dev, state, NULL);
-
- if (dev_pm_smart_suspend_and_suspended(dev) && no_subsys_cb)
+ if (dev_pm_smart_suspend_and_suspended(dev))
goto Skip;
if (dev->driver && dev->driver->pm) {
@@ -1351,13 +1303,16 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
Skip:
dev->power.is_noirq_suspended = true;
- if (dev_pm_test_driver_flags(dev, DPM_FLAG_LEAVE_SUSPENDED)) {
- dev->power.must_resume = dev->power.must_resume ||
- atomic_read(&dev->power.usage_count) > 1 ||
- device_must_resume(dev, state, no_subsys_cb);
- } else {
+ /*
+ * Skipping the resume of devices that were in use right before the
+ * system suspend (as indicated by their PM-runtime usage counters)
+ * would be suboptimal. Also resume them if doing that is not allowed
+ * to be skipped.
+ */
+ if (atomic_read(&dev->power.usage_count) > 1 ||
+ !(dev_pm_test_driver_flags(dev, DPM_FLAG_LEAVE_SUSPENDED) &&
+ dev->power.may_skip_resume))
dev->power.must_resume = true;
- }
if (dev->power.must_resume)
dpm_superior_set_must_resume(dev);
@@ -1539,9 +1494,14 @@ static int __device_suspend_late(struct device *dev, pm_message_t state, bool as
if (callback)
goto Run;
- if (dev_pm_smart_suspend_and_suspended(dev) &&
- !dpm_subsys_suspend_noirq_cb(dev, state, NULL))
+ if (dev_pm_smart_suspend_and_suspended(dev)) {
+ /*
+ * In principle, the resume of the device may be skippend if it
+ * remains in runtime suspend at this point.
+ */
+ dev->power.may_skip_resume = true;
goto Skip;
+ }
if (dev->driver && dev->driver->pm) {
info = "late driver ";
--
2.16.4
