[PATCH v7] PCI: Add pcie_link_is_active() to determine if the PCIe link

[PATCH v7] PCI: Add pcie_link_is_active() to determine if the PCIe link

[Timothy Pearson]

is active

Introduce a common API to check if the PCIe link is active, replacing
duplicate code in multiple locations.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
---
 arch/powerpc/kernel/eeh_driver.c  |  8 +++++++-
 drivers/pci/hotplug/pciehp.h      |  1 -
 drivers/pci/hotplug/pciehp_ctrl.c |  2 +-
 drivers/pci/hotplug/pciehp_hpc.c  | 33 +++----------------------------
 drivers/pci/pci.c                 | 31 ++++++++++++++++++++++++++---
 include/linux/pci.h               |  4 ++++
 6 files changed, 43 insertions(+), 36 deletions(-)

diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 441a3562bddd..4fdd62432f2c 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -1097,8 +1097,14 @@ void eeh_handle_normal_event(struct eeh_pe *pe)
 		eeh_pe_dev_mode_mark(pe, EEH_DEV_REMOVED);
 
 		pci_lock_rescan_remove();
-		pci_hp_remove_devices(bus);
+		bus = eeh_pe_bus_get(pe);
+		if (bus)
+			pci_hp_remove_devices(bus);
+		else
+			pr_err("%s: PCI bus for PHB#%x-PE#%x disappeared\n",
+				__func__, pe->phb->global_number, pe->addr);
 		pci_unlock_rescan_remove();
+
 		/* The passed PE should no longer be used */
 		return;
 	}
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index debc79b0adfb..79df49cc9946 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -186,7 +186,6 @@ int pciehp_query_power_fault(struct controller *ctrl);
 int pciehp_card_present(struct controller *ctrl);
 int pciehp_card_present_or_link_active(struct controller *ctrl);
 int pciehp_check_link_status(struct controller *ctrl);
-int pciehp_check_link_active(struct controller *ctrl);
 bool pciehp_device_replaced(struct controller *ctrl);
 void pciehp_release_ctrl(struct controller *ctrl);
 
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index bcc938d4420f..6cc1b27b3b11 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -260,7 +260,7 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
 	/* Turn the slot on if it's occupied or link is up */
 	mutex_lock(&ctrl->state_lock);
 	present = pciehp_card_present(ctrl);
-	link_active = pciehp_check_link_active(ctrl);
+	link_active = pcie_link_is_active(ctrl->pcie->port);
 	if (present <= 0 && link_active <= 0) {
 		if (ctrl->state == BLINKINGON_STATE) {
 			ctrl->state = OFF_STATE;
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index ebd342bda235..d29ce3715a44 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -221,33 +221,6 @@ static void pcie_write_cmd_nowait(struct controller *ctrl, u16 cmd, u16 mask)
 	pcie_do_write_cmd(ctrl, cmd, mask, false);
 }
 
-/**
- * pciehp_check_link_active() - Is the link active
- * @ctrl: PCIe hotplug controller
- *
- * Check whether the downstream link is currently active. Note it is
- * possible that the card is removed immediately after this so the
- * caller may need to take it into account.
- *
- * If the hotplug controller itself is not available anymore returns
- * %-ENODEV.
- */
-int pciehp_check_link_active(struct controller *ctrl)
-{
-	struct pci_dev *pdev = ctrl_dev(ctrl);
-	u16 lnk_status;
-	int ret;
-
-	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
-	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
-		return -ENODEV;
-
-	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
-	ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
-
-	return ret;
-}
-
 static bool pci_bus_check_dev(struct pci_bus *bus, int devfn)
 {
 	u32 l;
@@ -467,7 +440,7 @@ int pciehp_card_present_or_link_active(struct controller *ctrl)
 	if (ret)
 		return ret;
 
-	return pciehp_check_link_active(ctrl);
+	return pcie_link_is_active(ctrl_dev(ctrl));
 }
 
 int pciehp_query_power_fault(struct controller *ctrl)
@@ -614,7 +587,7 @@ static void pciehp_ignore_link_change(struct controller *ctrl,
 	 * Synthesize it to ensure that it is acted on.
 	 */
 	down_read_nested(&ctrl->reset_lock, ctrl->depth);
-	if (!pciehp_check_link_active(ctrl) || pciehp_device_replaced(ctrl))
+	if (!pcie_link_is_active(ctrl_dev(ctrl)) || pciehp_device_replaced(ctrl))
 		pciehp_request(ctrl, ignored_events);
 	up_read(&ctrl->reset_lock);
 }
@@ -921,7 +894,7 @@ int pciehp_slot_reset(struct pcie_device *dev)
 	pcie_capability_write_word(dev->port, PCI_EXP_SLTSTA,
 				   PCI_EXP_SLTSTA_DLLSC);
 
-	if (!pciehp_check_link_active(ctrl))
+	if (!pcie_link_is_active(ctrl_dev(ctrl)))
 		pciehp_request(ctrl, PCI_EXP_SLTSTA_DLLSC);
 
 	return 0;
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e9448d55113b..ad639e60f3bd 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4908,7 +4908,6 @@ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type)
 		return 0;
 
 	if (pcie_get_speed_cap(dev) <= PCIE_SPEED_5_0GT) {
-		u16 status;
 
 		pci_dbg(dev, "waiting %d ms for downstream link\n", delay);
 		msleep(delay);
@@ -4924,8 +4923,7 @@ int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type)
 		if (!dev->link_active_reporting)
 			return -ENOTTY;
 
-		pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &status);
-		if (!(status & PCI_EXP_LNKSTA_DLLLA))
+		if (pcie_link_is_active(dev) <= 0)
 			return -ENOTTY;
 
 		return pci_dev_wait(child, reset_type,
@@ -6230,6 +6228,33 @@ void pcie_print_link_status(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pcie_print_link_status);
 
+/**
+ * pcie_link_is_active() - Checks if the link is active or not
+ * @pdev: PCI device to query
+ *
+ * Check whether the physical link is active or not. Note it is
+ * possible that the card is removed immediately after this so the
+ * caller may need to take it into account.
+ *
+ * If the PCI device itself is not available anymore returns
+ * %-ENODEV.
+ *
+ * Return: link state, or -ENODEV if the config read failes.
+ */
+int pcie_link_is_active(struct pci_dev *pdev)
+{
+	u16 lnk_status;
+	int ret;
+
+	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
+	if (ret == PCIBIOS_DEVICE_NOT_FOUND || PCI_POSSIBLE_ERROR(lnk_status))
+		return -ENODEV;
+
+	pci_dbg(pdev, "lnk_status = %x\n", lnk_status);
+	return !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
+}
+EXPORT_SYMBOL(pcie_link_is_active);
+
 /**
  * pci_select_bars - Make BAR mask from the type of resource
  * @dev: the PCI device for which BAR mask is made
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 05e68f35f392..5d1c9f718ac8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1993,6 +1993,7 @@ pci_release_mem_regions(struct pci_dev *pdev)
 			    pci_select_bars(pdev, IORESOURCE_MEM));
 }
 
+int pcie_link_is_active(struct pci_dev *dev);
 #else /* CONFIG_PCI is not enabled */
 
 static inline void pci_set_flags(int flags) { }
@@ -2141,6 +2142,9 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
 {
 	return -ENOSPC;
 }
+
+static inline bool pcie_link_is_active(struct pci_dev *dev)
+{ return false; }
 #endif /* CONFIG_PCI */
 
 /* Include architecture-dependent settings and functions */
-- 
2.39.5

Re: [PATCH v7] PCI: Add pcie_link_is_active() to determine if the PCIe link

[Bjorn Helgaas]

On Tue, Jun 17, 2025 at 09:31:20AM -0500, Timothy Pearson wrote:
> is active
> 
> Introduce a common API to check if the PCIe link is active, replacing
> duplicate code in multiple locations.
> 
> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
> Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
> Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>

Duplicate post?  You can check https://lore.kernel.org/linux-pci/ to
see whether it appeared on the list.