Merge tag 'pm-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "These close a coverage gap in the intel_pstate driver and fix runtime
  PM child count imbalance related to interactions with system-wide
  suspend.

  Specifics:

   - Make intel_pstate work as expected on systems where the platform
     firmware enables HWP even though the HWP EPP support is not
     advertised (Rafael Wysocki).

   - Fix possible runtime PM child count imbalance that may occur if
     other runtime PM functions are called after invoking
     pm_runtime_force_suspend() and before pm_runtime_force_resume()
     is called (Tony Lindgren)"

* tag 'pm-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM: runtime: Fix unpaired parent child_count for force_resume
  cpufreq: intel_pstate: Use HWP if enabled by platform firmware

drivers/base/power/runtime.c

@@ -1637,6 +1637,7 @@ void pm_runtime_init(struct device *dev)
 	dev->power.request_pending = false;
 	dev->power.request = RPM_REQ_NONE;
 	dev->power.deferred_resume = false;
+	dev->power.needs_force_resume = 0;
 	INIT_WORK(&dev->power.work, pm_runtime_work);
 
 	dev->power.timer_expires = 0;
@@ -1804,10 +1805,12 @@ int pm_runtime_force_suspend(struct device *dev)
 	 * its parent, but set its status to RPM_SUSPENDED anyway in case this
 	 * function will be called again for it in the meantime.
 	 */
-	if (pm_runtime_need_not_resume(dev))
+	if (pm_runtime_need_not_resume(dev)) {
 		pm_runtime_set_suspended(dev);
-	else
+	} else {
 		__update_runtime_status(dev, RPM_SUSPENDED);
+		dev->power.needs_force_resume = 1;
+	}
 
 	return 0;
 
@@ -1834,7 +1837,7 @@ int pm_runtime_force_resume(struct device *dev)
 	int (*callback)(struct device *);
 	int ret = 0;
 
-	if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
+	if (!pm_runtime_status_suspended(dev) || !dev->power.needs_force_resume)
 		goto out;
 
 	/*
@@ -1853,6 +1856,7 @@ int pm_runtime_force_resume(struct device *dev)
 
 	pm_runtime_mark_last_busy(dev);
 out:
+	dev->power.needs_force_resume = 0;
 	pm_runtime_enable(dev);
 	return ret;
 }

drivers/cpufreq/intel_pstate.c

@@ -3033,6 +3033,14 @@ static const struct x86_cpu_id hwp_support_ids[] __initconst = {
 	{}
 };
 
+static bool intel_pstate_hwp_is_enabled(void)
+{
+	u64 value;
+
+	rdmsrl(MSR_PM_ENABLE, value);
+	return !!(value & 0x1);
+}
+
 static int __init intel_pstate_init(void)
 {
 	const struct x86_cpu_id *id;
@@ -3051,8 +3059,12 @@ static int __init intel_pstate_init(void)
 		 * Avoid enabling HWP for processors without EPP support,
 		 * because that means incomplete HWP implementation which is a
 		 * corner case and supporting it is generally problematic.
+		 *
+		 * If HWP is enabled already, though, there is no choice but to
+		 * deal with it.
 		 */
-		if (!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) {
+		if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) ||
+		    intel_pstate_hwp_is_enabled()) {
 			hwp_active++;
 			hwp_mode_bdw = id->driver_data;
 			intel_pstate.attr = hwp_cpufreq_attrs;

include/linux/pm.h

@@ -601,6 +601,7 @@ struct dev_pm_info {
 	unsigned int		idle_notification:1;
 	unsigned int		request_pending:1;
 	unsigned int		deferred_resume:1;
+	unsigned int		needs_force_resume:1;
 	unsigned int		runtime_auto:1;
 	bool			ignore_children:1;
 	unsigned int		no_callbacks:1;