PM / core: Add SMART_SUSPEND driver flag

Define and document a SMART_SUSPEND flag to instruct bus types and PM
domains that the system suspend callbacks provided by the driver can
cope with runtime-suspended devices, so from the driver's perspective
it should be safe to leave devices in runtime suspend during system
suspend.

Setting that flag may also cause middle-layer code (bus types,
PM domains etc.) to skip invocations of the ->suspend_late and
->suspend_noirq callbacks provided by the driver if the device
is in runtime suspend at the beginning of the "late" phase of
the system-wide suspend transition, in which case the driver's
system-wide resume callbacks may be invoked back-to-back with
its ->runtime_suspend callback, so the driver has to be able to
cope with that too.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/pm.h b/include/linux/pm.h
index f10bad831bfa..43b5418e05bb 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -558,6 +558,7 @@ struct pm_subsys_data {
  *
  * NEVER_SKIP: Do not skip system suspend/resume callbacks for the device.
  * SMART_PREPARE: Check the return value of the driver's ->prepare callback.
+ * SMART_SUSPEND: No need to resume the device from runtime suspend.
  *
  * Setting SMART_PREPARE instructs bus types and PM domains which may want
  * system suspend/resume callbacks to be skipped for the device to return 0 from
@@ -565,9 +566,16 @@ struct pm_subsys_data {
  * other words, the system suspend/resume callbacks can only be skipped for the
  * device if its driver doesn't object against that).  This flag has no effect
  * if NEVER_SKIP is set.
+ *
+ * Setting SMART_SUSPEND instructs bus types and PM domains which may want to
+ * runtime resume the device upfront during system suspend that doing so is not
+ * necessary from the driver's perspective.  It also may cause them to skip
+ * invocations of the ->suspend_late and ->suspend_noirq callbacks provided by
+ * the driver if they decide to leave the device in runtime suspend.
  */
 #define DPM_FLAG_NEVER_SKIP	BIT(0)
 #define DPM_FLAG_SMART_PREPARE	BIT(1)
+#define DPM_FLAG_SMART_SUSPEND	BIT(2)
 
 struct dev_pm_info {
 	pm_message_t		power_state;