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Subject[PATCH v3] PM / sleep: enable suspend-to-idle even without registered suspend_ops
Date
Suspend-to-idle (aka the "freeze" sleep state) is a system sleep state
in which all of the processors enter deepest possible idle state and
wait for interrupts right after suspending all the devices.

There is no hard requirement for a platform to support and register
platform specific suspend_ops to enter suspend-to-idle/freeze state.
Only deeper system sleep states like PM_SUSPEND_STANDBY and
PM_SUSPEND_MEM rely on such low level support/implementation.

suspend-to-idle can be entered as along as all the devices can be
suspended. This patch enables the support for suspend-to-idle even on
systems that don't have any low level support for deeper system sleep
states and/or don't register any platform specific suspend_ops.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
include/linux/suspend.h | 2 ++
kernel/power/main.c | 1 +
kernel/power/suspend.c | 14 +++++++++++---
3 files changed, 14 insertions(+), 3 deletions(-)

v2->v3:
- Renamed pm_freeze_init to pm_states_init
- Moved pm_states_init earlier in pm_init

v1->v2:
- Introduced pm_freeze_init instead of (mis/re)using suspend_set_ops
to setup freeze state in absense of registered platform suspend_ops

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 7693e39b14fe..d9718378a8be 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -245,6 +245,7 @@ static inline bool idle_should_freeze(void)
return unlikely(suspend_freeze_state == FREEZE_STATE_ENTER);
}

+extern void __init pm_states_init(void);
extern void freeze_set_ops(const struct platform_freeze_ops *ops);
extern void freeze_wake(void);

@@ -279,6 +280,7 @@ static inline bool pm_resume_via_firmware(void) { return false; }
static inline void suspend_set_ops(const struct platform_suspend_ops *ops) {}
static inline int pm_suspend(suspend_state_t state) { return -ENOSYS; }
static inline bool idle_should_freeze(void) { return false; }
+static inline void __init pm_states_init(void) {}
static inline void freeze_set_ops(const struct platform_freeze_ops *ops) {}
static inline void freeze_wake(void) {}
#endif /* !CONFIG_SUSPEND */
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 5ea50b1b7595..281a697fd458 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -644,6 +644,7 @@ static int __init pm_init(void)
return error;
hibernate_image_size_init();
hibernate_reserved_size_init();
+ pm_states_init();
power_kobj = kobject_create_and_add("power", NULL);
if (!power_kobj)
return -ENOMEM;
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 0acab9d7f96f..1e7f5da648d9 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -118,10 +118,18 @@ static bool valid_state(suspend_state_t state)
*/
static bool relative_states;

+void __init pm_states_init(void)
+{
+ /*
+ * freeze state should be supported even without any suspend_ops,
+ * initialize pm_states accordingly here
+ */
+ pm_states[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];
+}
+
static int __init sleep_states_setup(char *str)
{
relative_states = !strncmp(str, "1", 1);
- pm_states[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];
return 1;
}

@@ -211,7 +219,7 @@ static int platform_suspend_begin(suspend_state_t state)
{
if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin)
return freeze_ops->begin();
- else if (suspend_ops->begin)
+ else if (suspend_ops && suspend_ops->begin)
return suspend_ops->begin(state);
else
return 0;
@@ -221,7 +229,7 @@ static void platform_resume_end(suspend_state_t state)
{
if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end)
freeze_ops->end();
- else if (suspend_ops->end)
+ else if (suspend_ops && suspend_ops->end)
suspend_ops->end();
}

-
2.7.4

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