PCI PM: Make it possible to force using INTx for PCIe PME signaling

Apparently, some machines may have problems with PCI run-time power
management if MSIs are used for the native PCIe PME signaling.  In
particular, on the MSI Wind U-100 PCIe PME interrupts are not
generated by a PCIe root port after a resume from suspend to RAM, if
the system wake-up was triggered by a PME from the device attached to
this port.  [It doesn't help to free the interrupt on suspend and
request it back on resume, even if that is done along with disabling
the MSI and re-enabling it, respectively.]  However, if INTx
interrupts are used for this purpose on the same machine, everything
works just fine.

For this reason, add a kernel command line switch allowing one to
request that MSIs be not used for the native PCIe PME signaling,
introduce a DMI table allowing us to blacklist machines that need
this switch to be set by default and put the MSI Wind U-100 into this
table.

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

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index b174188ac121..0d34ff415399 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -186,16 +186,24 @@ static int pcie_port_enable_msix(struct pci_dev *dev, int *vectors, int mask)
  */
 static int init_service_irqs(struct pci_dev *dev, int *irqs, int mask)
 {
-	int i, irq;
+	int i, irq = -1;
+
+	/* We have to use INTx if MSI cannot be used for PCIe PME. */
+	if ((mask & PCIE_PORT_SERVICE_PME) && pcie_pme_no_msi()) {
+		if (dev->pin)
+			irq = dev->irq;
+		goto no_msi;
+	}
 
 	/* Try to use MSI-X if supported */
 	if (!pcie_port_enable_msix(dev, irqs, mask))
 		return 0;
+
 	/* We're not going to use MSI-X, so try MSI and fall back to INTx */
-	irq = -1;
 	if (!pci_enable_msi(dev) || dev->pin)
 		irq = dev->irq;
 
+ no_msi:
 	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)
 		irqs[i] = irq;
 	irqs[PCIE_PORT_SERVICE_VC_SHIFT] = -1;