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Subject[PATCH v8 2/2] PCI: pciehp: Mask AER surprise link down error if hotplug is enabled
Date
PCIe Spec 3.0. 7.10.2. Uncorrectable Error Status Register (Offset 04h)
defines link down errors as an AER error as bit 5 Surprise Down Error
Status.

If hotplug is supported by a particular port, we want hotplug driver
to handle the link down/up conditions via Data Link Layer Active
interrupt rather than the AER error interrupt. Mask the Surprise Down
Error during hotplug driver and re-enable it during remove.

Signed-off-by: Sinan Kaya <okaya@kernel.org>
---
drivers/pci/hotplug/pciehp_core.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index ec48c9433ae5..8322db8f369a 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -229,6 +229,29 @@ static void pciehp_check_presence(struct controller *ctrl)
up_read(&ctrl->reset_lock);
}

+static int pciehp_control_surprise_error(struct controller *ctrl, bool enable)
+{
+ struct pci_dev *pdev = ctrl->pcie->port;
+ u32 reg32;
+ int pos;
+
+ if (!pci_is_pcie(pdev))
+ return -ENODEV;
+
+ pos = pdev->aer_cap;
+ if (!pos)
+ return -ENODEV;
+
+ pci_read_config_dword(pdev, pos + PCI_ERR_UNCOR_MASK, &reg32);
+ if (enable)
+ reg32 &= ~PCI_ERR_UNC_SURPDN;
+ else
+ reg32 |= PCI_ERR_UNC_SURPDN;
+ pci_write_config_dword(pdev, pos + PCI_ERR_UNCOR_MASK, reg32);
+
+ return 0;
+}
+
static int pciehp_probe(struct pcie_device *dev)
{
int rc;
@@ -280,6 +303,9 @@ static int pciehp_probe(struct pcie_device *dev)

pciehp_check_presence(ctrl);

+ /* We want exclusive control of link down events in hotplug driver */
+ pciehp_control_surprise_error(ctrl, false);
+
return 0;

err_out_shutdown_notification:
@@ -298,6 +324,7 @@ static void pciehp_remove(struct pcie_device *dev)
pci_hp_del(ctrl->slot->hotplug_slot);
pcie_shutdown_notification(ctrl);
cleanup_slot(ctrl);
+ pciehp_control_surprise_error(ctrl, true);
pciehp_release_ctrl(ctrl);
}

--
2.17.1
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