[PATCH 5.4 089/111] PM: runtime: Defer suspending suppliers

From: Greg Kroah-Hartman
Date: Mon Mar 29 2021 - 04:24:37 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

[ Upstream commit 5244f5e2d801259af877ee759e8c22364c607072 ]

Because the PM-runtime status of the device is not updated in
__rpm_callback(), attempts to suspend the suppliers of the given
device triggered by the rpm_put_suppliers() call in there may
cause a supplier to be suspended completely before the status of
the consumer is updated to RPM_SUSPENDED, which is confusing.

To avoid that (1) modify __rpm_callback() to only decrease the
PM-runtime usage counter of each supplier and (2) make rpm_suspend()
try to suspend the suppliers after changing the consumer's status to
RPM_SUSPENDED, in analogy with the device's parent.

Link: https://lore.kernel.org/linux-pm/CAPDyKFqm06KDw_p8WXsM4dijDbho4bb6T4k50UqqvR1_COsp8g@xxxxxxxxxxxxxx/
Fixes: 21d5c57b3726 ("PM / runtime: Use device links")
Reported-by: elaine.zhang <zhangqing@xxxxxxxxxxxxxx>
Diagnosed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/base/power/runtime.c | 45 +++++++++++++++++++++++++++++++-----
1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 137a7ba053d7..e0c4ef06ca91 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -305,7 +305,7 @@ static int rpm_get_suppliers(struct device *dev)
return 0;
}

-static void rpm_put_suppliers(struct device *dev)
+static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
{
struct device_link *link;

@@ -313,10 +313,30 @@ static void rpm_put_suppliers(struct device *dev)
device_links_read_lock_held()) {

while (refcount_dec_not_one(&link->rpm_active))
- pm_runtime_put(link->supplier);
+ pm_runtime_put_noidle(link->supplier);
+
+ if (try_to_suspend)
+ pm_request_idle(link->supplier);
}
}

+static void rpm_put_suppliers(struct device *dev)
+{
+ __rpm_put_suppliers(dev, true);
+}
+
+static void rpm_suspend_suppliers(struct device *dev)
+{
+ struct device_link *link;
+ int idx = device_links_read_lock();
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+ device_links_read_lock_held())
+ pm_request_idle(link->supplier);
+
+ device_links_read_unlock(idx);
+}
+
/**
* __rpm_callback - Run a given runtime PM callback for a given device.
* @cb: Runtime PM callback to run.
@@ -344,8 +364,10 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
idx = device_links_read_lock();

retval = rpm_get_suppliers(dev);
- if (retval)
+ if (retval) {
+ rpm_put_suppliers(dev);
goto fail;
+ }

device_links_read_unlock(idx);
}
@@ -368,9 +390,9 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
|| (dev->power.runtime_status == RPM_RESUMING && retval))) {
idx = device_links_read_lock();

- fail:
- rpm_put_suppliers(dev);
+ __rpm_put_suppliers(dev, false);

+fail:
device_links_read_unlock(idx);
}

@@ -644,8 +666,11 @@ static int rpm_suspend(struct device *dev, int rpmflags)
goto out;
}

+ if (dev->power.irq_safe)
+ goto out;
+
/* Maybe the parent is now able to suspend. */
- if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
+ if (parent && !parent->power.ignore_children) {
spin_unlock(&dev->power.lock);

spin_lock(&parent->power.lock);
@@ -654,6 +679,14 @@ static int rpm_suspend(struct device *dev, int rpmflags)

spin_lock(&dev->power.lock);
}
+ /* Maybe the suppliers are now able to suspend. */
+ if (dev->power.links_count > 0) {
+ spin_unlock_irq(&dev->power.lock);
+
+ rpm_suspend_suppliers(dev);
+
+ spin_lock_irq(&dev->power.lock);
+ }

out:
trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
--
2.30.1