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[PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops

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  [PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops Sudeep Holla <sudeep.holla@arm.com> - 2016-08-18 11:20 +0200
    Re: [PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-08-18 13:10 +0200
      Re: [PATCH] PM / sleep: enable suspend-to-idle even without  registered suspend_ops Sudeep Holla <sudeep.holla@arm.com> - 2016-08-18 15:20 +0200
    [PATCH v2] PM / sleep: enable suspend-to-idle even without registered suspend_ops Sudeep Holla <sudeep.holla@arm.com> - 2016-08-18 19:30 +0200
      Re: [PATCH v2] PM / sleep: enable suspend-to-idle even without  registered suspend_ops "Rafael J. Wysocki" <rafael@kernel.org> - 2016-08-19 04:20 +0200
      [PATCH v3] PM / sleep: enable suspend-to-idle even without registered suspend_ops Sudeep Holla <sudeep.holla@arm.com> - 2016-08-19 15:50 +0200
        Re: [PATCH v3] PM / sleep: enable suspend-to-idle even without  registered suspend_ops Andy Gross <andy.gross@linaro.org> - 2016-08-24 07:20 +0200

#1465030 — [PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops

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>
---
 kernel/power/main.c    | 5 +++++
 kernel/power/suspend.c | 8 +++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

Hi Rafael,

I am not sure if you like this approach. I found this to be the simplest
but I may have missed to consider all possible corner cases especially
for x86 and other platforms. I don't see any such issues/cases with ARM
systems.

Regards,
Sudeep

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 5ea50b1b7595..0f0fd9184f39 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -651,6 +651,11 @@ static int __init pm_init(void)
 	if (error)
 		return error;
 	pm_print_times_init();
+	/*
+	 * freeze state should be supported even without any suspend_ops,
+	 * calling suspend_set_ops without any ops will setup freeze state
+	 */
+	suspend_set_ops(NULL);
 	return pm_autosleep_init();
 }

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 0acab9d7f96f..37d64f811ecd 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -138,7 +138,9 @@ void suspend_set_ops(const struct platform_suspend_ops *ops)

 	lock_system_sleep();

-	suspend_ops = ops;
+	WARN_ONCE(ops && suspend_ops, "overriding suspend_ops");
+	if (ops)
+		suspend_ops = ops;
 	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
 		if (valid_state(i)) {
 			pm_states[i] = pm_labels[j++];
@@ -211,7 +213,7 @@ 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 +223,7 @@ 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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#1465166

On Thursday, August 18, 2016 10:19:24 AM Sudeep Holla wrote:
> 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>
> ---
>  kernel/power/main.c    | 5 +++++
>  kernel/power/suspend.c | 8 +++++---
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> Hi Rafael,
> 
> I am not sure if you like this approach. I found this to be the simplest
> but I may have missed to consider all possible corner cases especially
> for x86 and other platforms. I don't see any such issues/cases with ARM
> systems.
>
> diff --git a/kernel/power/main.c b/kernel/power/main.c
> index 5ea50b1b7595..0f0fd9184f39 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -651,6 +651,11 @@ static int __init pm_init(void)
>  	if (error)
>  		return error;
>  	pm_print_times_init();
> +	/*
> +	 * freeze state should be supported even without any suspend_ops,
> +	 * calling suspend_set_ops without any ops will setup freeze state
> +	 */
> +	suspend_set_ops(NULL);

Well, this is a core initcall, so suspend_set_ops() invocations from platforms
really should happen after that, so something like this should be sufficient here:

	pm_state[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? PM_SUSPEND_MEM : PM_SUSPEND_FREEZE];

if I'm not mistaken.

>  	return pm_autosleep_init();
>  }
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 0acab9d7f96f..37d64f811ecd 100644
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -138,7 +138,9 @@ void suspend_set_ops(const struct platform_suspend_ops *ops)
> 
>  	lock_system_sleep();
> 
> -	suspend_ops = ops;
> +	WARN_ONCE(ops && suspend_ops, "overriding suspend_ops");
> +	if (ops)
> +		suspend_ops = ops;

And this should not be necessary then.

>  	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
>  		if (valid_state(i)) {
>  			pm_states[i] = pm_labels[j++];
> @@ -211,7 +213,7 @@ 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 +223,7 @@ 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();
>  }

And this is still needed, of course.

Thanks,
Rafael

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#1465296 — Re: [PATCH] PM / sleep: enable suspend-to-idle even without registered suspend_ops

On 18/08/16 12:06, Rafael J. Wysocki wrote:
> On Thursday, August 18, 2016 10:19:24 AM Sudeep Holla wrote:
>> 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>
>> ---
>>  kernel/power/main.c    | 5 +++++
>>  kernel/power/suspend.c | 8 +++++---
>>  2 files changed, 10 insertions(+), 3 deletions(-)
>>
>> Hi Rafael,
>>
>> I am not sure if you like this approach. I found this to be the simplest
>> but I may have missed to consider all possible corner cases especially
>> for x86 and other platforms. I don't see any such issues/cases with ARM
>> systems.
>>
>> diff --git a/kernel/power/main.c b/kernel/power/main.c
>> index 5ea50b1b7595..0f0fd9184f39 100644
>> --- a/kernel/power/main.c
>> +++ b/kernel/power/main.c
>> @@ -651,6 +651,11 @@ static int __init pm_init(void)
>>  	if (error)
>>  		return error;
>>  	pm_print_times_init();
>> +	/*
>> +	 * freeze state should be supported even without any suspend_ops,
>> +	 * calling suspend_set_ops without any ops will setup freeze state
>> +	 */
>> +	suspend_set_ops(NULL);
>
> Well, this is a core initcall, so suspend_set_ops() invocations from platforms
> really should happen after that, so something like this should be sufficient here:
>
> 	pm_state[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? PM_SUSPEND_MEM : PM_SUSPEND_FREEZE];
>
> if I'm not mistaken.
>

But won't this show up as "standby" state in /sys/power/state ?
Or did you mean:
	pm_state[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];

which will be "mem" or "freeze" based on relative_states.

In-fact, I did exactly this when I first hacked. Since it exposed
incorrectly to sysfs and I was not sure of these relative_states and
it's usage, I preferred re-using suspend_set_ops for this.

IIUC showing freeze state as "mem" in sysfs is fine as that's the
deepest possible state when relative_states=1. But showing it as freeze
as "standby" in sysfs when relative_states=0 looked wrong to me though
it works as freeze state.

As a side-note with psci, it get called quite early before
core_initcall. But that can be fixed if needed and is different issue.

-- 
Regards,
Sudeep

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#1465653 — [PATCH v2] PM / sleep: enable suspend-to-idle even without registered suspend_ops

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(-)

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..0528ee32be7c 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_freeze_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_freeze_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..f27c2f2d0f22 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -651,6 +651,7 @@ static int __init pm_init(void)
 	if (error)
 		return error;
 	pm_print_times_init();
+	pm_freeze_init();
 	return pm_autosleep_init();
 }

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 0acab9d7f96f..1c962a366678 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_freeze_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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#1465899 — Re: [PATCH v2] PM / sleep: enable suspend-to-idle even without registered suspend_ops

On Thu, Aug 18, 2016 at 6:42 PM, Sudeep Holla <sudeep.holla@arm.com> wrote:
> 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(-)
>
> 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..0528ee32be7c 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_freeze_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_freeze_init(void) {}

Why don't you call it pm_states_init()?

>  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..f27c2f2d0f22 100644
> --- a/kernel/power/main.c
> +++ b/kernel/power/main.c
> @@ -651,6 +651,7 @@ static int __init pm_init(void)
>         if (error)
>                 return error;
>         pm_print_times_init();
> +       pm_freeze_init();

And please move this up (before the registration of power_kobj).

>         return pm_autosleep_init();
>  }
>
> diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
> index 0acab9d7f96f..1c962a366678 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_freeze_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();
>  }
>
> --

Thanks,
Rafael

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#1466433 — [PATCH v3] PM / sleep: enable suspend-to-idle even without registered suspend_ops

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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#1469075 — Re: [PATCH v3] PM / sleep: enable suspend-to-idle even without registered suspend_ops

On 19 August 2016 at 08:41, Sudeep Holla <sudeep.holla@arm.com> wrote:
> 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>

I tested this patch on the Qualcomm 410c platform.  It worked like a
charm.  Thanks for working on this!

Tested-by: Andy Gross <andy.gross@linaro.org>

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