PCI/PCIe: Clear Root PME Status bits early during system resume

I noticed that PCI Express PMEs don't work on my Toshiba Portege R500
after the system has been woken up from a sleep state by a PME
(through Wake-on-LAN).  After some investigation it turned out that
the BIOS didn't clear the Root PME Status bit in the root port that
received the wakeup PME and since the Requester ID was also set in
the port's Root Status register, any subsequent PMEs didn't trigger
interrupts.

This problem can be avoided by clearing the Root PME Status bits in
all PCI Express root ports during early resume.  For this purpose,
add an early resume routine to the PCIe port driver and make this
driver be always registered, even if pci_ports_disable is set (in
which case the driver's only function is to provide the early
resume callback).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 33 insertions, 4 deletions

diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index f9033e1..e0610bd 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -57,6 +57,22 @@ __setup("pcie_ports=", pcie_port_setup);
 
 /* global data */
 
+/**
+ * pcie_clear_root_pme_status - Clear root port PME interrupt status.
+ * @dev: PCIe root port or event collector.
+ */
+void pcie_clear_root_pme_status(struct pci_dev *dev)
+{
+	int rtsta_pos;
+	u32 rtsta;
+
+	rtsta_pos = pci_pcie_cap(dev) + PCI_EXP_RTSTA;
+
+	pci_read_config_dword(dev, rtsta_pos, &rtsta);
+	rtsta |= PCI_EXP_RTSTA_PME;
+	pci_write_config_dword(dev, rtsta_pos, rtsta);
+}
+
 static int pcie_portdrv_restore_config(struct pci_dev *dev)
 {
 	int retval;
@@ -69,6 +85,20 @@ static int pcie_portdrv_restore_config(struct pci_dev *dev)
 }
 
 #ifdef CONFIG_PM
+static int pcie_port_resume_noirq(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	/*
+	 * Some BIOSes forget to clear Root PME Status bits after system wakeup
+	 * which breaks ACPI-based runtime wakeup on PCI Express, so clear those
+	 * bits now just in case (shouldn't hurt).
+	 */
+	if(pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT)
+		pcie_clear_root_pme_status(pdev);
+	return 0;
+}
+
 static const struct dev_pm_ops pcie_portdrv_pm_ops = {
 	.suspend	= pcie_port_device_suspend,
 	.resume		= pcie_port_device_resume,
@@ -76,6 +106,7 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
 	.thaw		= pcie_port_device_resume,
 	.poweroff	= pcie_port_device_suspend,
 	.restore	= pcie_port_device_resume,
+	.resume_noirq	= pcie_port_resume_noirq,
 };
 
 #define PCIE_PORTDRV_PM_OPS	(&pcie_portdrv_pm_ops)
@@ -327,10 +358,8 @@ static int __init pcie_portdrv_init(void)
 {
 	int retval;
 
-	if (pcie_ports_disabled) {
-		pcie_no_aspm();
-		return -EACCES;
-	}
+	if (pcie_ports_disabled)
+		return pci_register_driver(&pcie_portdriver);
 
 	dmi_check_system(pcie_portdrv_dmi_table);