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[RFC][PATCH 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware

Started by"Rafael J. Wysocki" <rjw@rjwysocki.net>
First post2015-09-30 02:30 +0200
Last post2015-10-02 03:30 +0200
Articles 5 — 1 participant

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  [RFC][PATCH 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-30 02:30 +0200
    [RFC][PATCH 1/2] PM / sleep: Add flags to indicate platform firmware involvement "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-09-30 02:30 +0200
    [RFC][PATCH v2 2/2] PM / PCI / ACPI: Kick devices that might have been reset by firmware "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-02 03:30 +0200
    [RFC][PATCH v2 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-02 03:30 +0200
      [RFC][PATCH v2 1/2] PM / sleep: Add flags to indicate platform firmware involvement "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-02 03:30 +0200

#1235654 — [RFC][PATCH 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware

From"Rafael J. Wysocki" <rjw@rjwysocki.net>
Date2015-09-30 02:30 +0200
Subject[RFC][PATCH 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware
Message-ID<qedrr-5yV-3@gated-at.bofh.it>
Hi All,

Patch [1/2] introduces a new mechanism that can be used to check whether or not
platform firmware is going to be involved in system suspend or was involved
in system resume.

Patch [2/2] modifies the PM core to use the mechanism added by [1/2].

Comments welcome.

Thanks,
Rafael

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#1235655 — [RFC][PATCH 1/2] PM / sleep: Add flags to indicate platform firmware involvement

From"Rafael J. Wysocki" <rjw@rjwysocki.net>
Date2015-09-30 02:30 +0200
Subject[RFC][PATCH 1/2] PM / sleep: Add flags to indicate platform firmware involvement
Message-ID<qedrr-5yV-11@gated-at.bofh.it>
In reply to#1235654
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

There are quite a few cases in which device drivers, bus types or
even the PM core itself may benefit from knowing whether or not
the platform firmware will be involved in the upcoming system power
transition (during system suspend) or whether or not it was involved
in it (during system resume).

For this reason, introduce global system suspend flags that can be
used by the platform code to expose that information for the benefit
of the other parts of the kernel and make the ACPI core set them
as appropriate.

Users of the new flags will be added later.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/sleep.c    |    3 +++
 include/linux/suspend.h |   30 ++++++++++++++++++++++++++++++
 kernel/power/suspend.c  |    3 +++
 3 files changed, 36 insertions(+)

Index: linux-pm/include/linux/suspend.h
===================================================================
--- linux-pm.orig/include/linux/suspend.h
+++ linux-pm/include/linux/suspend.h
@@ -202,6 +202,36 @@ struct platform_freeze_ops {
 extern void suspend_set_ops(const struct platform_suspend_ops *ops);
 extern int suspend_valid_only_mem(suspend_state_t state);
 
+extern unsigned int pm_suspend_global_flags;
+
+#define PM_SUSPEND_FLAG_FW_SUSPEND	(1 << 0)
+#define PM_SUSPEND_FLAG_FW_RESUME	(1 << 1)
+
+static inline void pm_suspend_clear_flags(void)
+{
+	pm_suspend_global_flags = 0;
+}
+
+static inline void pm_set_suspend_via_firmware(void)
+{
+	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_SUSPEND;
+}
+
+static inline void pm_set_resume_via_firmware(void)
+{
+	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_RESUME;
+}
+
+static inline bool pm_suspend_via_firmware(void)
+{
+	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_SUSPEND);
+}
+
+static inline bool pm_resume_via_firmware(void)
+{
+	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_RESUME);
+}
+
 /* Suspend-to-idle state machnine. */
 enum freeze_state {
 	FREEZE_STATE_NONE,      /* Not suspended/suspending. */
Index: linux-pm/kernel/power/suspend.c
===================================================================
--- linux-pm.orig/kernel/power/suspend.c
+++ linux-pm/kernel/power/suspend.c
@@ -35,6 +35,8 @@
 const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
 const char *pm_states[PM_SUSPEND_MAX];
 
+unsigned int pm_suspend_global_flags;
+
 static const struct platform_suspend_ops *suspend_ops;
 static const struct platform_freeze_ops *freeze_ops;
 static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
@@ -493,6 +495,7 @@ static int enter_state(suspend_state_t s
 #endif
 
 	pr_debug("PM: Preparing system for sleep (%s)\n", pm_states[state]);
+	pm_suspend_clear_flags();
 	error = suspend_prepare(state);
 	if (error)
 		goto Unlock;
Index: linux-pm/drivers/acpi/sleep.c
===================================================================
--- linux-pm.orig/drivers/acpi/sleep.c
+++ linux-pm/drivers/acpi/sleep.c
@@ -487,6 +487,8 @@ static int acpi_suspend_begin(suspend_st
 		pr_err("ACPI does not support sleep state S%u\n", acpi_state);
 		return -ENOSYS;
 	}
+	if (acpi_state > ACPI_STATE_S1)
+		pm_set_suspend_via_firmware();
 
 	acpi_pm_start(acpi_state);
 	return 0;
@@ -522,6 +524,7 @@ static int acpi_suspend_enter(suspend_st
 		if (error)
 			return error;
 		pr_info(PREFIX "Low-level resume complete\n");
+		pm_set_resume_via_firmware();
 		break;
 	}
 	trace_suspend_resume(TPS("acpi_suspend"), acpi_state, false);
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#1237865 — [RFC][PATCH v2 2/2] PM / PCI / ACPI: Kick devices that might have been reset by firmware

From"Rafael J. Wysocki" <rjw@rjwysocki.net>
Date2015-10-02 03:30 +0200
Subject[RFC][PATCH v2 2/2] PM / PCI / ACPI: Kick devices that might have been reset by firmware
Message-ID<qeXkB-5f4-1@gated-at.bofh.it>
In reply to#1235654
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

There is a concern that if the platform firmware was involved in
the system resume that's being completed,  some devices might have
been reset by it and if those devices had the power.direct_complete
flag set during the preceding suspend transition, they may stay
in a reset-power-on state indefinitely (until they are runtime-resumed
and then suspended again).  That may not be a big deal from the
individual device's perspective, but if the system is an SoC, it may
be prevented from entering deep SoC-wide low-power states on idle
because of that.

The devices that are most likely to be affected by this issue are
PCI devices and ACPI-enumerated devices using the general ACPI PM
domain, so to prevent it from happening for those devices, force a
runtime resume for them if they have their power.direct_complete
flags set and the platform firmware was involved in the resume
transition currently in progress.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: Do it for devices that are most likely to be affected (PCI and the
ACPI PM domain users) rather than for all devices in the system.

---
 drivers/acpi/acpi_lpss.c         |    2 +-
 drivers/acpi/device_pm.c         |   19 +------------------
 drivers/base/power/generic_ops.c |   23 +++++++++++++++++++++++
 drivers/pci/pci-driver.c         |    2 +-
 include/linux/pm.h               |    2 +-
 5 files changed, 27 insertions(+), 21 deletions(-)

Index: linux-pm/drivers/acpi/device_pm.c
===================================================================
--- linux-pm.orig/drivers/acpi/device_pm.c
+++ linux-pm/drivers/acpi/device_pm.c
@@ -963,23 +963,6 @@ int acpi_subsys_prepare(struct device *d
 EXPORT_SYMBOL_GPL(acpi_subsys_prepare);
 
 /**
- * acpi_subsys_complete - Finalize device's resume during system resume.
- * @dev: Device to handle.
- */
-void acpi_subsys_complete(struct device *dev)
-{
-	pm_generic_complete(dev);
-	/*
-	 * If the device had been runtime-suspended before the system went into
-	 * the sleep state it is going out of and it has never been resumed till
-	 * now, resume it in case the firmware powered it up.
-	 */
-	if (dev->power.direct_complete)
-		pm_request_resume(dev);
-}
-EXPORT_SYMBOL_GPL(acpi_subsys_complete);
-
-/**
  * acpi_subsys_suspend - Run the device driver's suspend callback.
  * @dev: Device to handle.
  *
@@ -1047,7 +1030,7 @@ static struct dev_pm_domain acpi_general
 		.runtime_resume = acpi_subsys_runtime_resume,
 #ifdef CONFIG_PM_SLEEP
 		.prepare = acpi_subsys_prepare,
-		.complete = acpi_subsys_complete,
+		.complete = pm_complete_with_resume_check,
 		.suspend = acpi_subsys_suspend,
 		.suspend_late = acpi_subsys_suspend_late,
 		.resume_early = acpi_subsys_resume_early,
Index: linux-pm/drivers/acpi/acpi_lpss.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpi_lpss.c
+++ linux-pm/drivers/acpi/acpi_lpss.c
@@ -664,7 +664,7 @@ static struct dev_pm_domain acpi_lpss_pm
 #ifdef CONFIG_PM
 #ifdef CONFIG_PM_SLEEP
 		.prepare = acpi_subsys_prepare,
-		.complete = acpi_subsys_complete,
+		.complete = pm_complete_with_resume_check,
 		.suspend = acpi_subsys_suspend,
 		.suspend_late = acpi_lpss_suspend_late,
 		.resume_early = acpi_lpss_resume_early,
Index: linux-pm/drivers/base/power/generic_ops.c
===================================================================
--- linux-pm.orig/drivers/base/power/generic_ops.c
+++ linux-pm/drivers/base/power/generic_ops.c
@@ -9,6 +9,7 @@
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/export.h>
+#include <linux/suspend.h>
 
 #ifdef CONFIG_PM
 /**
@@ -297,4 +298,26 @@ void pm_generic_complete(struct device *
 	if (drv && drv->pm && drv->pm->complete)
 		drv->pm->complete(dev);
 }
+
+/**
+ * pm_complete_with_resume_check - Complete a device power transition.
+ * @dev: Device to handle.
+ *
+ * Complete a device power transition during a system-wide power transition and
+ * optionally schedule a runtime resume of the device if the system resume in
+ * progress has been initated by the platform firmware and the device had its
+ * power.direct_complete flag set.
+ */
+void pm_complete_with_resume_check(struct device *dev)
+{
+	pm_generic_complete(dev);
+	/*
+	 * If the device had been runtime-suspended before the system went into
+	 * the sleep state it is going out of and it has never been resumed till
+	 * now, resume it in case the firmware powered it up.
+	 */
+	if (dev->power.direct_complete && pm_resume_via_firmware())
+		pm_request_resume(dev);
+}
+EXPORT_SYMBOL_GPL(pm_complete_with_resume_check);
 #endif /* CONFIG_PM_SLEEP */
Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -687,7 +687,7 @@ static int pci_pm_prepare(struct device
 static void pci_pm_complete(struct device *dev)
 {
 	pci_dev_complete_resume(to_pci_dev(dev));
-	pm_generic_complete(dev);
+	pm_complete_with_resume_check(dev);
 }
 
 #else /* !CONFIG_PM_SLEEP */
Index: linux-pm/include/linux/pm.h
===================================================================
--- linux-pm.orig/include/linux/pm.h
+++ linux-pm/include/linux/pm.h
@@ -731,7 +731,7 @@ extern int pm_generic_restore(struct dev
 extern int pm_generic_poweroff_noirq(struct device *dev);
 extern int pm_generic_poweroff_late(struct device *dev);
 extern int pm_generic_poweroff(struct device *dev);
-extern void pm_generic_complete(struct device *dev);
+extern void pm_complete_with_resume_check(struct device *dev);
 
 #else /* !CONFIG_PM_SLEEP */
 

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#1237866 — [RFC][PATCH v2 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware

From"Rafael J. Wysocki" <rjw@rjwysocki.net>
Date2015-10-02 03:30 +0200
Subject[RFC][PATCH v2 0/2] PM / sleep: Make it possible to check if suspend/resume goes via firmware
Message-ID<qeXkB-5f4-3@gated-at.bofh.it>
In reply to#1235654
On Wednesday, September 30, 2015 02:46:10 AM Rafael J. Wysocki wrote:
> Hi All,
> 
> Patch [1/2] introduces a new mechanism that can be used to check whether or not
> platform firmware is going to be involved in system suspend or was involved
> in system resume.

That's still the case, but patch [2/2] modifies the PCI PM layer and the general
ACPI PM domain only to use the mechanism added by the [1/2].

Comments welcome.

Thanks,
Rafael

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#1237873 — [RFC][PATCH v2 1/2] PM / sleep: Add flags to indicate platform firmware involvement

From"Rafael J. Wysocki" <rjw@rjwysocki.net>
Date2015-10-02 03:30 +0200
Subject[RFC][PATCH v2 1/2] PM / sleep: Add flags to indicate platform firmware involvement
Message-ID<qeXkC-5f4-19@gated-at.bofh.it>
In reply to#1237866
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

There are quite a few cases in which device drivers, bus types or
even the PM core itself may benefit from knowing whether or not
the platform firmware will be involved in the upcoming system power
transition (during system suspend) or whether or not it was involved
in it (during system resume).

For this reason, introduce global system suspend flags that can be
used by the platform code to expose that information for the benefit
of the other parts of the kernel and make the ACPI core set them
as appropriate.

Users of the new flags will be added later.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: Apply EXPORT_SYMBOL_GPL() to pm_suspend_global_flags so modular
drivers can use it too.

---
 drivers/acpi/sleep.c    |    3 +++
 include/linux/suspend.h |   36 ++++++++++++++++++++++++++++++++++++
 kernel/power/suspend.c  |    4 ++++
 3 files changed, 43 insertions(+)

Index: linux-pm/include/linux/suspend.h
===================================================================
--- linux-pm.orig/include/linux/suspend.h
+++ linux-pm/include/linux/suspend.h
@@ -202,6 +202,36 @@ struct platform_freeze_ops {
 extern void suspend_set_ops(const struct platform_suspend_ops *ops);
 extern int suspend_valid_only_mem(suspend_state_t state);
 
+extern unsigned int pm_suspend_global_flags;
+
+#define PM_SUSPEND_FLAG_FW_SUSPEND	(1 << 0)
+#define PM_SUSPEND_FLAG_FW_RESUME	(1 << 1)
+
+static inline void pm_suspend_clear_flags(void)
+{
+	pm_suspend_global_flags = 0;
+}
+
+static inline void pm_set_suspend_via_firmware(void)
+{
+	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_SUSPEND;
+}
+
+static inline void pm_set_resume_via_firmware(void)
+{
+	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_RESUME;
+}
+
+static inline bool pm_suspend_via_firmware(void)
+{
+	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_SUSPEND);
+}
+
+static inline bool pm_resume_via_firmware(void)
+{
+	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_RESUME);
+}
+
 /* Suspend-to-idle state machnine. */
 enum freeze_state {
 	FREEZE_STATE_NONE,      /* Not suspended/suspending. */
@@ -241,6 +271,12 @@ extern int pm_suspend(suspend_state_t st
 #else /* !CONFIG_SUSPEND */
 #define suspend_valid_only_mem	NULL
 
+static inline void pm_suspend_clear_flags(void) {}
+static inline void pm_set_suspend_via_firmware(void) {}
+static inline void pm_set_resume_via_firmware(void) {}
+static inline bool pm_suspend_via_firmware(void) { return false; }
+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; }
Index: linux-pm/kernel/power/suspend.c
===================================================================
--- linux-pm.orig/kernel/power/suspend.c
+++ linux-pm/kernel/power/suspend.c
@@ -35,6 +35,9 @@
 const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
 const char *pm_states[PM_SUSPEND_MAX];
 
+unsigned int pm_suspend_global_flags;
+EXPORT_SYMBOL_GPL(pm_suspend_global_flags);
+
 static const struct platform_suspend_ops *suspend_ops;
 static const struct platform_freeze_ops *freeze_ops;
 static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
@@ -493,6 +496,7 @@ static int enter_state(suspend_state_t s
 #endif
 
 	pr_debug("PM: Preparing system for sleep (%s)\n", pm_states[state]);
+	pm_suspend_clear_flags();
 	error = suspend_prepare(state);
 	if (error)
 		goto Unlock;
Index: linux-pm/drivers/acpi/sleep.c
===================================================================
--- linux-pm.orig/drivers/acpi/sleep.c
+++ linux-pm/drivers/acpi/sleep.c
@@ -487,6 +487,8 @@ static int acpi_suspend_begin(suspend_st
 		pr_err("ACPI does not support sleep state S%u\n", acpi_state);
 		return -ENOSYS;
 	}
+	if (acpi_state > ACPI_STATE_S1)
+		pm_set_suspend_via_firmware();
 
 	acpi_pm_start(acpi_state);
 	return 0;
@@ -522,6 +524,7 @@ static int acpi_suspend_enter(suspend_st
 		if (error)
 			return error;
 		pr_info(PREFIX "Low-level resume complete\n");
+		pm_set_resume_via_firmware();
 		break;
 	}
 	trace_suspend_resume(TPS("acpi_suspend"), acpi_state, false);

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