linux-kernel - [PATCH] PM / sleep: Avoid excess pm_runtime_enable() calls in device

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Date:   Thu, 07 Dec 2017 03:26:14 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     Linux PCI <linux-pci@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH] PM / sleep: Avoid excess pm_runtime_enable() calls in device_resume()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Middle-layer code doing suspend-time optimizations for devices with
the DPM_FLAG_SMART_SUSPEND flag set (currently, the PCI bus type and
the ACPI PM domain) needs to make the core skip ->thaw_early and
->thaw callbacks for those devices in some cases and it sets the
power.direct_complete flag for them for this purpose.

However, it turns out that setting power.direct_complete outside of
the PM core is a bad idea as it triggers an excessive invocation of
pm_runtime_enable() in device_resume().

For this reason, provide a helper to clear power.is_late_suspended
and power.is_suspended to be invoked by the middle-layer code in
question instead of setting power.direct_complete and make that code
call the new helper.

Fixes: c4b65157aeef (PCI / PM: Take SMART_SUSPEND driver flag into account)
Fixes: 05087360fd7a (ACPI / PM: Take SMART_SUSPEND driver flag into account)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/device_pm.c  |    2 +-
 drivers/base/power/main.c |   15 +++++++++++++++
 drivers/pci/pci-driver.c  |    2 +-
 include/linux/pm.h        |    1 +
 4 files changed, 18 insertions(+), 2 deletions(-)

Index: linux-pm/include/linux/pm.h
===================================================================
--- linux-pm.orig/include/linux/pm.h
+++ linux-pm/include/linux/pm.h
@@ -765,6 +765,7 @@ extern int pm_generic_poweroff_late(stru
 extern int pm_generic_poweroff(struct device *dev);
 extern void pm_generic_complete(struct device *dev);
 
+extern void dev_pm_skip_next_resume_phases(struct device *dev);
 extern bool dev_pm_smart_suspend_and_suspended(struct device *dev);
 
 #else /* !CONFIG_PM_SLEEP */
Index: linux-pm/drivers/base/power/main.c
===================================================================
--- linux-pm.orig/drivers/base/power/main.c
+++ linux-pm/drivers/base/power/main.c
@@ -526,6 +526,21 @@ static void dpm_watchdog_clear(struct dp
 /*------------------------- Resume routines -------------------------*/
 
 /**
+ * dev_pm_skip_next_resume_phases - Skip next system resume phases for device.
+ * @dev: Target device.
+ *
+ * Make the core skip the "early resume" and "resume" phases for @dev.
+ *
+ * This function can be called by middle-layer code during the "noirq" phase of
+ * system resume if necessary, but not by device drivers.
+ */
+void dev_pm_skip_next_resume_phases(struct device *dev)
+{
+	dev->power.is_late_suspended = false;
+	dev->power.is_suspended = false;
+}
+
+/**
  * device_resume_noirq - Execute a "noirq resume" callback for given device.
  * @dev: Device to handle.
  * @state: PM transition of the system being carried out.
Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -999,7 +999,7 @@ static int pci_pm_thaw_noirq(struct devi
 	 * the subsequent "thaw" callbacks for the device.
 	 */
 	if (dev_pm_smart_suspend_and_suspended(dev)) {
-		dev->power.direct_complete = true;
+		dev_pm_skip_next_resume_phases(dev);
 		return 0;
 	}
 
Index: linux-pm/drivers/acpi/device_pm.c
===================================================================
--- linux-pm.orig/drivers/acpi/device_pm.c
+++ linux-pm/drivers/acpi/device_pm.c
@@ -1138,7 +1138,7 @@ int acpi_subsys_thaw_noirq(struct device
 	 * skip all of the subsequent "thaw" callbacks for the device.
 	 */
 	if (dev_pm_smart_suspend_and_suspended(dev)) {
-		dev->power.direct_complete = true;
+		dev_pm_skip_next_resume_phases(dev);
 		return 0;
 	}