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PM: sleep: core: Simplify the SMART_SUSPEND flag handling

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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.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
This commit is contained in:
Rafael J. Wysocki 2020-04-18 18:29:30 +02:00
parent ae83d0b416
commit 107d47b2b9
1 changed files with 39 additions and 79 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

118
drivers/base/power/main.c
View file

@ -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 ";