PM / PCI / ACPI: Kick devices that might have been reset by firmware

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>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/base/power/generic_ops.c b/drivers/base/power/generic_ops.c
index b2ed606265a8..07c3c4a9522d 100644
--- a/drivers/base/power/generic_ops.c
+++ b/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 *dev)
         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 */