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-rw-r--r--include/linux/pm.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 73c610573a74..d6dd6f612b8d 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -320,6 +320,15 @@ const struct dev_pm_ops name = { \
/*
* Use this for defining a set of PM operations to be used in all situations
* (sustem suspend, hibernation or runtime PM).
+ * NOTE: In general, system suspend callbacks, .suspend() and .resume(), should
+ * be different from the corresponding runtime PM callbacks, .runtime_suspend(),
+ * and .runtime_resume(), because .runtime_suspend() always works on an already
+ * quiescent device, while .suspend() should assume that the device may be doing
+ * something when it is called (it should ensure that the device will be
+ * quiescent after it has returned). Therefore it's better to point the "late"
+ * suspend and "early" resume callback pointers, .suspend_late() and
+ * .resume_early(), to the same routines as .runtime_suspend() and
+ * .runtime_resume(), respectively (and analogously for hibernation).
*/
#define UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) \
const struct dev_pm_ops name = { \