[PATCH 2/3] PCI/AER: Disable AER service on suspend

[Kai-Heng Feng <kai.heng.feng@canonical.com>]

When the power rail gets cut off, the hardware can create some electric
noise on the link that triggers AER. If IRQ is shared between AER with
PME, such AER noise will cause a spurious wakeup on system suspend.

When the power rail gets back, the firmware of the device resets itself
and can create unexpected behavior like sending PTM messages. For this
case, the driver will always be too late to toggle off features should
be disabled.

As Per PCIe Base Spec 5.0, section 5.2, titled "Link State Power
Management", TLP and DLLP transmission are disabled for a Link in L2/L3
Ready (D3hot), L2 (D3cold with aux power) and L3 (D3cold) states. So if
the power will be turned off during suspend process, disable AER service
and re-enable it during the resume process. This should not affect the
basic functionality.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=209149
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216295

v7:
 - Wording
 - Disable AER completely (again) if power will be turned off

v6:
v5:
 - Wording.

v4:
v3:
 - No change.

v2:
 - Only disable AER IRQ.
 - No more check on PME IRQ#.
 - Use helper.
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/pci/pcie/aer.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index f6c24ded134c..b5161bfedd8b 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -28,6 +28,7 @@
 #include <linux/delay.h>
 #include <linux/kfifo.h>
 #include <linux/slab.h>
+#include <linux/suspend.h>
 #include <acpi/apei.h>
 #include <ras/ras_event.h>
 
@@ -1340,6 +1341,28 @@ static int aer_probe(struct pcie_device *dev)
 	return 0;
 }
 
+static int aer_suspend(struct pcie_device *dev)
+{
+	struct aer_rpc *rpc = get_service_data(dev);
+	struct pci_dev *pdev = rpc->rpd;
+
+	if (pci_ancestor_pr3_present(pdev) || pm_suspend_via_firmware())
+		aer_disable_rootport(rpc);
+
+	return 0;
+}
+
+static int aer_resume(struct pcie_device *dev)
+{
+	struct aer_rpc *rpc = get_service_data(dev);
+	struct pci_dev *pdev = rpc->rpd;
+
+	if (pci_ancestor_pr3_present(pdev) || pm_resume_via_firmware())
+		aer_enable_rootport(rpc);
+
+	return 0;
+}
+
 /**
  * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
  * @dev: pointer to Root Port, RCEC, or RCiEP
@@ -1411,6 +1434,8 @@ static struct pcie_port_service_driver aerdriver = {
 	.service	= PCIE_PORT_SERVICE_AER,
 
 	.probe		= aer_probe,
+	.suspend	= aer_suspend,
+	.resume		= aer_resume,
 	.remove		= aer_remove,
 };
 
-- 
2.34.1