3 files changed, 53 insertions, 0 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index f8436d1c4d45..c8d0549580f4 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -519,6 +519,46 @@ static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
 	return PCI_POWER_ERROR;
 }
 
+static struct acpi_device *acpi_pci_find_companion(struct device *dev);
+
+static bool acpi_pci_bridge_d3(struct pci_dev *dev)
+{
+	const struct fwnode_handle *fwnode;
+	struct acpi_device *adev;
+	struct pci_dev *root;
+	u8 val;
+
+	if (!dev->is_hotplug_bridge)
+		return false;
+
+	/*
+	 * Look for a special _DSD property for the root port and if it
+	 * is set we know the hierarchy behind it supports D3 just fine.
+	 */
+	root = pci_find_pcie_root_port(dev);
+	if (!root)
+		return false;
+
+	adev = ACPI_COMPANION(&root->dev);
+	if (root == dev) {
+		/*
+		 * It is possible that the ACPI companion is not yet bound
+		 * for the root port so look it up manually here.
+		 */
+		if (!adev && !pci_dev_is_added(root))
+			adev = acpi_pci_find_companion(&root->dev);
+	}
+
+	if (!adev)
+		return false;
+
+	fwnode = acpi_fwnode_handle(adev);
+	if (fwnode_property_read_u8(fwnode, "HotPlugSupportInD3", &val))
+		return false;
+
+	return val == 1;
+}
+
 static bool acpi_pci_power_manageable(struct pci_dev *dev)
 {
 	struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
@@ -635,6 +675,7 @@ static bool acpi_pci_need_resume(struct pci_dev *dev)
 }
 
 static const struct pci_platform_pm_ops acpi_pci_platform_pm = {
+	.bridge_d3 = acpi_pci_bridge_d3,
 	.is_manageable = acpi_pci_power_manageable,
 	.set_state = acpi_pci_set_power_state,
 	.get_state = acpi_pci_get_power_state,
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4a1b1f76dc92..e6fcf11f5dcc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -793,6 +793,11 @@ static inline bool platform_pci_need_resume(struct pci_dev *dev)
 	return pci_platform_pm ? pci_platform_pm->need_resume(dev) : false;
 }
 
+static inline bool platform_pci_bridge_d3(struct pci_dev *dev)
+{
+	return pci_platform_pm ? pci_platform_pm->bridge_d3(dev) : false;
+}
+
 /**
  * pci_raw_set_power_state - Use PCI PM registers to set the power state of
  *                           given PCI device
@@ -2518,6 +2523,10 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
 		if (bridge->is_thunderbolt)
 			return true;
 
+		/* Platform might know better if the bridge supports D3 */
+		if (platform_pci_bridge_d3(bridge))
+			return true;
+
 		/*
 		 * Hotplug ports handled natively by the OS were not validated
 		 * by vendors for runtime D3 at least until 2018 because there
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index eb3125decffe..672ba4d1659e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -40,6 +40,8 @@ int pci_bus_error_reset(struct pci_dev *dev);
 /**
  * struct pci_platform_pm_ops - Firmware PM callbacks
  *
+ * @bridge_d3: Does the bridge allow entering into D3
+ *
  * @is_manageable: returns 'true' if given device is power manageable by the
  *		   platform firmware
  *
@@ -61,6 +63,7 @@ int pci_bus_error_reset(struct pci_dev *dev);
  * these callbacks are mandatory.
  */
 struct pci_platform_pm_ops {
+	bool (*bridge_d3)(struct pci_dev *dev);
 	bool (*is_manageable)(struct pci_dev *dev);
 	int (*set_state)(struct pci_dev *dev, pci_power_t state);
 	pci_power_t (*get_state)(struct pci_dev *dev);