PM: Allow device drivers to use dpm_wait()
There are some dependencies between devices (in particular, between
EHCI USB controllers and their OHCI/UHCI siblings) which are not
reflected by the structure of the device tree. With synchronous
suspend and resume these dependencies are taken into accout
automatically, because the devices in question are always registered
in the right order, but to meet these constraints with asynchronous
suspend and resume the drivers of these devices will need to use
dpm_wait() in their suspend/resume routines, so introduce a helper
function allowing them to do that.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 6efef9f..0e26a6f 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1046,3 +1046,14 @@
printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
}
EXPORT_SYMBOL_GPL(__suspend_report_result);
+
+/**
+ * device_pm_wait_for_dev - Wait for suspend/resume of a device to complete.
+ * @dev: Device to wait for.
+ * @subordinate: Device that needs to wait for @dev.
+ */
+void device_pm_wait_for_dev(struct device *subordinate, struct device *dev)
+{
+ dpm_wait(dev, subordinate->power.async_suspend);
+}
+EXPORT_SYMBOL_GPL(device_pm_wait_for_dev);
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 9c16cd2..e80df06 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -512,6 +512,7 @@
__suspend_report_result(__func__, fn, ret); \
} while (0)
+extern void device_pm_wait_for_dev(struct device *sub, struct device *dev);
#else /* !CONFIG_PM_SLEEP */
#define device_pm_lock() do {} while (0)
@@ -524,6 +525,7 @@
#define suspend_report_result(fn, ret) do {} while (0)
+static inline void device_pm_wait_for_dev(struct device *a, struct device *b) {}
#endif /* !CONFIG_PM_SLEEP */
/* How to reorder dpm_list after device_move() */
