PCI: Clear Secondary Status errors after enumeration

We enumerate devices by attempting config reads to the Vendor ID of each
possible device.  On conventional PCI, if no device responds, the read
terminates with a Master Abort (PCI r3.0, sec 6.1).  On PCIe, the config
read is terminated as an Unsupported Request (PCIe r6.0, sec 2.3.2,
7.5.1.3.7).  In either case, if the read addressed a device below a bridge,
it is logged by setting "Received Master Abort" in the bridge Secondary
Status register.

Clear any errors logged in the Secondary Status register after enumeration.

Link: https://lore.kernel.org/r/20240116143258.483235-1-vidyas@nvidia.com
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[bhelgaas: simplify commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 1325fbae2f28fb10dbbbd6c6ff65ce2cf9193f3d..df5171b912e006b3a229dee008e5ea7c163d0af6 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1482,6 +1482,9 @@ static int pci_scan_bridge_extend(struct pci_bus *bus, struct pci_dev *dev,
        }
 
 out:
+       /* Clear errors in the Secondary Status Register */
+       pci_write_config_word(dev, PCI_SEC_STATUS, 0xffff);
+
        pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
 
        pm_runtime_put(&dev->dev);