From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Wed, 26 Jun 2019 00:20:23 +0200
Subject: PCI: PM: Avoid skipping bus-level PM on platforms without ACPI
Git-commit: 471a739a47aa7d582f0cdf9d392957d04632bae2
Patch-mainline: 5.2-rc7
References: git-fixes

There are platforms that do not call pm_set_suspend_via_firmware(),
so pm_suspend_via_firmware() returns 'false' on them, but the power
states of PCI devices (PCIe ports in particular) are changed as a
result of powering down core platform components during system-wide
suspend.  Thus the pm_suspend_via_firmware() checks in
pci_pm_suspend_noirq() and pci_pm_resume_noirq() introduced by
commit 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to-
idle") are not sufficient to determine that devices left in D0
during suspend will remain in D0 during resume and so the bus-level
power management can be skipped for them.

For this reason, introduce a new global suspend flag,
PM_SUSPEND_FLAG_NO_PLATFORM, set it for suspend-to-idle only
and replace the pm_suspend_via_firmware() checks mentioned above
with checks against this flag.

[js] use PM_SUSPEND_FREEZE instead of PM_SUSPEND_TO_IDLE

Fixes: 3e26c5feed2a ("PCI: PM: Skip devices in D0 for suspend-to-idle")
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/pci/pci-driver.c |    8 ++++----
 include/linux/suspend.h  |   26 ++++++++++++++++++++++++--
 kernel/power/suspend.c   |    3 +++
 3 files changed, 31 insertions(+), 6 deletions(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -861,7 +861,7 @@ static int pci_pm_suspend_noirq(struct d
 			pci_dev->bus->self->skip_bus_pm = true;
 	}
 
-	if (pci_dev->skip_bus_pm && !pm_suspend_via_firmware()) {
+	if (pci_dev->skip_bus_pm && pm_suspend_no_platform()) {
 		dev_dbg(dev, "PCI PM: Skipped\n");
 		goto Fixup;
 	}
@@ -916,10 +916,10 @@ static int pci_pm_resume_noirq(struct de
 	/*
 	 * In the suspend-to-idle case, devices left in D0 during suspend will
 	 * stay in D0, so it is not necessary to restore or update their
-	 * configuration here and attempting to put them into D0 again may
-	 * confuse some firmware, so avoid doing that.
+	 * configuration here and attempting to put them into D0 again is
+	 * pointless, so avoid doing that.
 	 */
-	if (!pci_dev->skip_bus_pm || pm_suspend_via_firmware())
+	if (!(pci_dev->skip_bus_pm && pm_suspend_no_platform()))
 		pci_pm_default_resume_early(pci_dev);
 
 	pci_fixup_device(pci_fixup_resume_early, pci_dev);
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -205,8 +205,9 @@ extern int suspend_valid_only_mem(suspen
 
 extern unsigned int pm_suspend_global_flags;
 
-#define PM_SUSPEND_FLAG_FW_SUSPEND	(1 << 0)
-#define PM_SUSPEND_FLAG_FW_RESUME	(1 << 1)
+#define PM_SUSPEND_FLAG_FW_SUSPEND	BIT(0)
+#define PM_SUSPEND_FLAG_FW_RESUME	BIT(1)
+#define PM_SUSPEND_FLAG_NO_PLATFORM	BIT(2)
 
 static inline void pm_suspend_clear_flags(void)
 {
@@ -223,6 +224,11 @@ static inline void pm_set_resume_via_fir
 	pm_suspend_global_flags |= PM_SUSPEND_FLAG_FW_RESUME;
 }
 
+static inline void pm_set_suspend_no_platform(void)
+{
+	pm_suspend_global_flags |= PM_SUSPEND_FLAG_NO_PLATFORM;
+}
+
 static inline bool pm_suspend_via_firmware(void)
 {
 	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_SUSPEND);
@@ -233,6 +239,22 @@ static inline bool pm_resume_via_firmwar
 	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_FW_RESUME);
 }
 
+/**
+ * pm_suspend_no_platform - Check if platform may change device power states.
+ *
+ * To be called during system-wide power management transitions to sleep states
+ * or during the subsequent system-wide transitions back to the working state.
+ *
+ * Return 'true' if the power states of devices remain under full control of the
+ * kernel throughout the system-wide suspend and resume cycle in progress (that
+ * is, if a device is put into a certain power state during suspend, it can be
+ * expected to remain in that state during resume).
+ */
+static inline bool pm_suspend_no_platform(void)
+{
+	return !!(pm_suspend_global_flags & PM_SUSPEND_FLAG_NO_PLATFORM);
+}
+
 /* Suspend-to-idle state machnine. */
 enum freeze_state {
 	FREEZE_STATE_NONE,      /* Not suspended/suspending. */
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -455,6 +455,9 @@ int suspend_devices_and_enter(suspend_st
 	if (!sleep_state_supported(state))
 		return -ENOSYS;
 
+	if (state == PM_SUSPEND_FREEZE)
+		pm_set_suspend_no_platform();
+
 	error = platform_suspend_begin(state);
 	if (error)
 		goto Close;