Drivers on embedded systems would be smart enough to know that some
of the devices _should_ remain powered up, because they could still
be useful even when the CPU wasn't running. The only obstacle is
letting the drivers know when their devices actually _are_ in use
and sometimes this is apparent only at the application level.
The patch add the no_suspend attribute and it can be used by the
the drivers to stop power down during suspend.
Signed-off-by: Michael Trimarchi <trimarchi@xxxxxxxxxxxxxxxx>
Cc: "Alan Stern" <stern@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: "Pavel Mackek" <pavel@xxxxxx>
Cc: "Len Brown" <lenb@xxxxxxxxxx>
---
drivers/base/power/main.c | 54 +++++++++++++++++++++++++++++++++++++++++++-
drivers/base/power/power.h | 5 ++++
include/linux/device.h | 1 +
include/linux/pm.h | 3 ++
4 files changed, 62 insertions(+), 1 deletions(-)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 69b4ddb..baae309 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -65,6 +65,45 @@ void device_pm_unlock(void)
}
/**
+ * device_set_no_suspend_enable - Mark the device as used by userspace
+ * application
+ */
+void device_set_no_suspend_enable(struct device *dev, bool enable)
+{
+ struct device *next;
+
+ mutex_lock(&dpm_list_mtx);
+
+ /* the new status is equal the old one */
+ if (dev->power.no_suspend == !!enable)
+ goto out;
+
+ /* change the device status */
+ dev->power.no_suspend = !!enable;
+ if (dev->power.no_suspend)
+ dev->power.subtree_no_suspend = 0;
+
+ list_for_each_entry_reverse(next, &dev->power.entry, power.entry) {
+ /*
+ * exit if we find a node with the same parent of the start
+ * device
+ */
+ if (dev->parent && next->parent == dev->parent)
+ break;
+
+ if (next->parent) {
+ /* Propagate the status */
+ next->power.subtree_no_suspend =
+ device_no_suspend_enable(next->parent);
+ }
+ }
+out:
+ mutex_unlock(&dpm_list_mtx);
+ return;
+}
+EXPORT_SYMBOL_GPL(device_set_no_suspend_enable);
+
+/**
* device_pm_add - add a device to the list of active devices
* @dev: Device to be added to the list
*/
@@ -78,6 +117,11 @@ void device_pm_add(struct device *dev)
if (dev->parent->power.status >= DPM_SUSPENDING)
dev_warn(dev, "parent %s should not be sleeping\n",
dev_name(dev->parent));
+ if (device_no_suspend_enable(dev->parent)) {
+ /* if the parent has suspend disable, propagate it
+ * to the new child */
+ dev->power.subtree_no_suspend = 1;
+ }
} else if (transition_started) {
/*
* We refuse to register parentless devices while a PM
@@ -87,7 +131,15 @@ void device_pm_add(struct device *dev)
dev_WARN(dev, "Parentless device registered during a PM transaction\n");
}
- list_add_tail(&dev->power.entry, &dpm_list);
+ if (dev->parent) {
+ /*
+ * if the device has a parent insert just before it.
+ */
+ list_add_tail(&dev->power.entry, &(dev->parent)->power.entry);
+ }
+ else
+ list_add_tail(&dev->power.entry, &dpm_list);
+
mutex_unlock(&dpm_list_mtx);
}
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index c7cb4fc..a997b20 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -3,6 +3,11 @@ static inline void device_pm_init(struct device *dev)
dev->power.status = DPM_ON;
}
+static inline int device_no_suspend_enable(struct device *dev)
+{
+ return dev->power.no_suspend || dev->power.subtree_no_suspend;
+}
+
#ifdef CONFIG_PM_SLEEP
/*
diff --git a/include/linux/device.h b/include/linux/device.h
index 2918c0e..74ca60d 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -496,6 +496,7 @@ extern struct device *device_find_child(struct device *dev, void *data,
extern int device_rename(struct device *dev, char *new_name);
extern int device_move(struct device *dev, struct device *new_parent,
enum dpm_order dpm_order);
+extern void device_set_no_suspend_enable(struct device *dev, bool enable);
/*
* Root device objects for grouping under /sys/devices
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 1d4e2d2..e664d63 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -319,6 +319,9 @@ struct dev_pm_info {
pm_message_t power_state;
unsigned can_wakeup:1;
unsigned should_wakeup:1;
+ unsigned no_suspend:1;
+ unsigned subtree_no_suspend:1;
+
enum dpm_state status; /* Owned by the PM core */
#ifdef CONFIG_PM_SLEEP
struct list_head entry;
--
1.5.6.5
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