power management: force pm_ops.valid callback to be assigned
This patch changes the docs and behaviour from "all states valid" to "no
states valid" if no .valid callback is assigned. Users of pm_ops that only
need mem sleep can assign pm_valid_only_mem without any overhead, others
will require more elaborate callbacks.
Now that all users of pm_ops have a .valid callback this is a safe thing to
do and prevents things from getting messy again as they were before.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Looks-okay-to: Rafael J. Wysocki <rjw@sisk.pl>
Cc: <linux-pm@lists.linux-foundation.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 6035209..7a51669 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -125,12 +125,12 @@
* struct pm_ops - Callbacks for managing platform dependent suspend states.
* @valid: Callback to determine whether the given state can be entered.
* If %CONFIG_SOFTWARE_SUSPEND is set then %PM_SUSPEND_DISK is
- * always valid and never passed to this call.
- * If not assigned, all suspend states are advertised as valid
- * in /sys/power/state (but can still be rejected by prepare or enter.)
- * Since new states can be added for other platforms, you should
- * assign this callback. There is a %pm_valid_only_mem function
- * available if you only implemented mem sleep.
+ * always valid and never passed to this call. If not assigned,
+ * no suspend states are valid.
+ * Valid states are advertised in /sys/power/state but can still
+ * be rejected by prepare or enter if the conditions aren't right.
+ * There is a %pm_valid_only_mem function available that can be assigned
+ * to this if you only implement mem sleep.
*
* @prepare: Prepare the platform for the given suspend state. Can return a
* negative error code if necessary.
diff --git a/kernel/power/main.c b/kernel/power/main.c
index f94f4e2..72419a3 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -198,8 +198,8 @@
/* all other states need lowlevel support and need to be
* valid to the lowlevel implementation, no valid callback
- * implies that all are valid. */
- if (!pm_ops || (pm_ops->valid && !pm_ops->valid(state)))
+ * implies that none are valid. */
+ if (!pm_ops || !pm_ops->valid || !pm_ops->valid(state))
return 0;
return 1;
}