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Message-id: <1466144820-6286-4-git-send-email-m.szyprowski@samsung.com>
Date: Fri, 17 Jun 2016 08:26:53 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
iommu@...ts.linux-foundation.org,
linux-samsung-soc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
Joerg Roedel <joro@...tes.org>,
Inki Dae <inki.dae@...sung.com>, Kukjin Kim <kgene@...nel.org>,
Krzysztof Kozlowski <k.kozlowski@...sung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Ulf Hansson <ulf.hansson@...aro.org>,
Mark Brown <broonie@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH v2 03/10] PM core: 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>
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
drivers/base/base.h | 2 ++
drivers/base/core.c | 4 +--
drivers/base/power/main.c | 68 ++++++++++++++++++++++++++++++++++++++++++-----
3 files changed, 66 insertions(+), 8 deletions(-)
diff --git a/drivers/base/base.h b/drivers/base/base.h
index cccb1d211541..123b986eb061 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -163,3 +163,5 @@ extern void device_links_driver_gone(struct device *dev);
extern void device_links_no_driver(struct device *dev);
extern bool device_links_busy(struct device *dev);
extern void device_links_unbind_consumers(struct device *dev);
+extern int device_links_read_lock(void);
+extern void device_links_read_unlock(int idx);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 416341df3268..51a479ed68b5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -163,12 +163,12 @@ void device_link_del(struct devlink *link)
}
EXPORT_SYMBOL_GPL(device_link_del);
-static int device_links_read_lock(void)
+int device_links_read_lock(void)
{
return srcu_read_lock(&device_links_srcu);
}
-static void device_links_read_unlock(int idx)
+void device_links_read_unlock(int idx)
{
return srcu_read_unlock(&device_links_srcu, idx);
}
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index e44944f4be77..9470ccd87f11 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -244,6 +244,62 @@ static void dpm_wait_for_children(struct device *dev, bool async)
device_for_each_child(dev, &async, dpm_wait_fn);
}
+static void dpm_wait_for_suppliers(struct device *dev, bool async)
+{
+ struct devlink *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->consumer_links, c_node)
+ if (link->status != DEVICE_LINK_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 devlink *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->supplier_links, s_node)
+ if (link->status != DEVICE_LINK_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.
@@ -488,7 +544,7 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn
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 ";
@@ -618,7 +674,7 @@ static int device_resume_early(struct device *dev, pm_message_t state, bool asyn
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 ";
@@ -750,7 +806,7 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
goto Complete;
}
- dpm_wait(dev->parent, async);
+ dpm_wait_for_superior(dev, async);
dpm_watchdog_set(&wd, dev);
device_lock(dev);
@@ -1038,7 +1094,7 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
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 ";
@@ -1185,7 +1241,7 @@ static int __device_suspend_late(struct device *dev, pm_message_t state, bool as
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 ";
@@ -1358,7 +1414,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
TRACE_DEVICE(dev);
TRACE_SUSPEND(0);
- dpm_wait_for_children(dev, async);
+ dpm_wait_for_subordinate(dev, async);
if (async_error)
goto Complete;
--
1.9.1
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