[PATCH v7 1/4] PCI/ERR: Add support for resetting the Root Ports in a platform specific way

Manivannan Sadhasivam via B4 Relay
2026-03-10T14:02:25Z

From: Manivannan Sadhasivam <mani@kernel.org>

Some host bridge devices require resetting the Root Ports in a platform
specific way to recover them from error conditions such as Fatal AER
errors, Link Down etc... So introduce pci_host_bridge::reset_root_port()
callback and call it from pcibios_reset_secondary_bus() if available. Also,
save the Root Port config space before reset and restore it afterwards.

The 'reset_root_port' callback is responsible for resetting the given Root
Port referenced by the 'pci_dev' pointer in a platform specific way and
bring it back to the working state if possible. If any error occurs during
the reset operation, relevant errno should be returned.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Tested-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---
drivers/pci/pci.c | 20 ++++++++++++++++++++
drivers/pci/pcie/err.c | 5 -----
include/linux/pci.h | 1 +
3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8479c2e1f74f..6f09057d83e0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4812,6 +4812,26 @@ void pci_reset_secondary_bus(struct pci_dev *dev)

void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
{
+ struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
+ int ret;
+
+ if (pci_is_root_bus(dev->bus) && host->reset_root_port) {
+ /*
+ * Save the config space of the Root Port before doing the
+ * reset, since the state could be lost. The Endpoint state
+ * should've been saved by the caller.
+ */
+ pci_save_state(dev);
+ ret = host->reset_root_port(host, dev);
+ if (ret)
+ pci_err(dev, "Failed to reset Root Port: %d\n", ret);
+ else
+ /* Now restore it on success */
+ pci_restore_state(dev);
+
+ return;
+ }
+
pci_reset_secondary_bus(dev);
}

diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index bebe4bc111d7..13b9d9eb714f 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -256,11 +256,6 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
}

if (status == PCI_ERS_RESULT_NEED_RESET) {
- /*
- * TODO: Should call platform-specific
- * functions to reset slot before calling
- * drivers' slot_reset callbacks?
- */
status = PCI_ERS_RESULT_RECOVERED;
pci_dbg(bridge, "broadcast slot_reset message\n");
pci_walk_bridge(bridge, report_slot_reset, &status);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1c270f1d5123..34c434b79abb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -644,6 +644,7 @@ struct pci_host_bridge {
void (*release_fn)(struct pci_host_bridge *);
int (*enable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev);
void (*disable_device)(struct pci_host_bridge *bridge, struct pci_dev *dev);
+ int (*reset_root_port)(struct pci_host_bridge *bridge, struct pci_dev *dev);
void *release_data;
unsigned int ignore_reset_delay:1; /* For entire hierarchy */
unsigned int no_ext_tags:1; /* No Extended Tags */

--
2.51.0