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Date: Mon, 10 Oct 2016 14:54:32 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM list <linux-pm@...r.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Alan Stern <stern@...land.harvard.edu>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Tomeu Vizoso <tomeu.vizoso@...labora.com>,
Mark Brown <broonie@...nel.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Lukas Wunner <lukas@...ner.de>,
Kevin Hilman <khilman@...nel.org>,
Ulf Hansson <ulf.hansson@...aro.org>,
"Luis R. Rodriguez" <mcgrof@...e.com>
Subject: [PATCH v5 3/5] PM / sleep: Make async suspend/resume of devices use device links
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Make the device suspend/resume part of the core system
suspend/resume code use device links to ensure that supplier
and consumer devices will be suspended and resumed in the right
order in case of async suspend/resume.
The idea, roughly, is to use dpm_wait() to wait for all consumers
before a supplier device suspend and to wait for all suppliers
before a consumer device resume.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
v4 -> v5:
- Rebase, change the symbol names in accordance with patch [2/5] etc.
- Use READ_ONCE() to annotate "unprotected" accesses to link status data.
---
drivers/base/power/main.c | 85 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 79 insertions(+), 6 deletions(-)
Index: linux-pm/drivers/base/power/main.c
===================================================================
--- linux-pm.orig/drivers/base/power/main.c
+++ linux-pm/drivers/base/power/main.c
@@ -246,6 +246,62 @@ static void dpm_wait_for_children(struct
device_for_each_child(dev, &async, dpm_wait_fn);
}
+static void dpm_wait_for_suppliers(struct device *dev, bool async)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ /*
+ * If the supplier goes away right after we've checked the link to it,
+ * we'll wait for its completion to change the state, but that's fine,
+ * because the only things that will block as a result are the SRCU
+ * callbacks freeing the link objects for the links in the list we're
+ * walking.
+ */
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+ if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+ dpm_wait(link->supplier, async);
+
+ device_links_read_unlock(idx);
+}
+
+static void dpm_wait_for_superior(struct device *dev, bool async)
+{
+ dpm_wait(dev->parent, async);
+ dpm_wait_for_suppliers(dev, async);
+}
+
+static void dpm_wait_for_consumers(struct device *dev, bool async)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ /*
+ * The status of a device link can only be changed from "dormant" by a
+ * probe, but that cannot happen during system suspend/resume. In
+ * theory it can change to "dormant" at that time, but then it is
+ * reasonable to wait for the target device anyway (eg. if it goes
+ * away, it's better to wait for it to go away completely and then
+ * continue instead of trying to continue in parallel with its
+ * unregistration).
+ */
+ list_for_each_entry_rcu(link, &dev->links.consumers, s_node)
+ if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+ dpm_wait(link->consumer, async);
+
+ device_links_read_unlock(idx);
+}
+
+static void dpm_wait_for_subordinate(struct device *dev, bool async)
+{
+ dpm_wait_for_children(dev, async);
+ dpm_wait_for_consumers(dev, async);
+}
+
/**
* pm_op - Return the PM operation appropriate for given PM event.
* @ops: PM operations to choose from.
@@ -490,7 +546,7 @@ static int device_resume_noirq(struct de
if (!dev->power.is_noirq_suspended)
goto Out;
- dpm_wait(dev->parent, async);
+ dpm_wait_for_superior(dev, async);
if (dev->pm_domain) {
info = "noirq power domain ";
@@ -620,7 +676,7 @@ static int device_resume_early(struct de
if (!dev->power.is_late_suspended)
goto Out;
- dpm_wait(dev->parent, async);
+ dpm_wait_for_superior(dev, async);
if (dev->pm_domain) {
info = "early power domain ";
@@ -752,7 +808,7 @@ static int device_resume(struct device *
goto Complete;
}
- dpm_wait(dev->parent, async);
+ dpm_wait_for_superior(dev, async);
dpm_watchdog_set(&wd, dev);
device_lock(dev);
@@ -1040,7 +1096,7 @@ static int __device_suspend_noirq(struct
if (dev->power.syscore || dev->power.direct_complete)
goto Complete;
- dpm_wait_for_children(dev, async);
+ dpm_wait_for_subordinate(dev, async);
if (dev->pm_domain) {
info = "noirq power domain ";
@@ -1187,7 +1243,7 @@ static int __device_suspend_late(struct
if (dev->power.syscore || dev->power.direct_complete)
goto Complete;
- dpm_wait_for_children(dev, async);
+ dpm_wait_for_subordinate(dev, async);
if (dev->pm_domain) {
info = "late power domain ";
@@ -1344,6 +1400,22 @@ static int legacy_suspend(struct device
return error;
}
+static void dpm_clear_suppliers_direct_complete(struct device *dev)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+ spin_lock_irq(&link->supplier->power.lock);
+ link->supplier->power.direct_complete = false;
+ spin_unlock_irq(&link->supplier->power.lock);
+ }
+
+ device_links_read_unlock(idx);
+}
+
/**
* device_suspend - Execute "suspend" callbacks for given device.
* @dev: Device to handle.
@@ -1360,7 +1432,7 @@ static int __device_suspend(struct devic
TRACE_DEVICE(dev);
TRACE_SUSPEND(0);
- dpm_wait_for_children(dev, async);
+ dpm_wait_for_subordinate(dev, async);
if (async_error)
goto Complete;
@@ -1456,6 +1528,7 @@ static int __device_suspend(struct devic
spin_unlock_irq(&parent->power.lock);
}
+ dpm_clear_suppliers_direct_complete(dev);
}
device_unlock(dev);
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