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 <[email protected]>
Signed-off-by: Jesse Barnes <[email protected]>

drivers/pci/pcie/pme/pcie_pme.c

@@ -53,12 +53,22 @@ static bool pcie_pme_disabled;
  */
 static bool pcie_pme_force_enable;
 
+/*
+ * If this switch is set, MSI will not be used for PCIe PME signaling.  This
+ * causes the PCIe port driver to use INTx interrupts only, but it turns out
+ * that using MSI for PCIe PME signaling doesn't play well with PCIe PME-based
+ * wake-up from system sleep states.
+ */
+bool pcie_pme_msi_disabled;
+
 static int __init pcie_pme_setup(char *str)
 {
 	if (!strcmp(str, "off"))
 		pcie_pme_disabled = true;
 	else if (!strcmp(str, "force"))
 		pcie_pme_force_enable = true;
+	else if (!strcmp(str, "nomsi"))
+		pcie_pme_msi_disabled = true;
 	return 1;
 }
 __setup("pcie_pme=", pcie_pme_setup);
@@ -73,7 +83,9 @@ __setup("pcie_pme=", pcie_pme_setup);
  */
 static bool pcie_pme_platform_setup(struct pcie_device *srv)
 {
-	return !pcie_pme_platform_notify(srv) || pcie_pme_force_enable;
+	if (!pcie_pme_platform_notify(srv))
+		return true;
+	return pcie_pme_force_enable;
 }
 
 struct pcie_pme_service_data {

drivers/pci/pcie/portdrv.h

@@ -30,4 +30,21 @@ extern void pcie_port_device_remove(struct pci_dev *dev);
 extern int __must_check pcie_port_bus_register(void);
 extern void pcie_port_bus_unregister(void);
 
+#ifdef CONFIG_PCIE_PME
+extern bool pcie_pme_msi_disabled;
+
+static inline void pcie_pme_disable_msi(void)
+{
+	pcie_pme_msi_disabled = true;
+}
+
+static inline bool pcie_pme_no_msi(void)
+{
+	return pcie_pme_msi_disabled;
+}
+#else /* !CONFIG_PCIE_PME */
+static inline void pcie_pme_disable_msi(void) {}
+static inline bool pcie_pme_no_msi(void) { return false; }
+#endif /* !CONFIG_PCIE_PME */
+
 #endif /* _PORTDRV_H_ */

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;

drivers/pci/pcie/portdrv_pci.c

@@ -15,6 +15,7 @@
 #include <linux/slab.h>
 #include <linux/pcieport_if.h>
 #include <linux/aer.h>
+#include <linux/dmi.h>
 
 #include "portdrv.h"
 #include "aer/aerdrv.h"
@@ -273,10 +274,36 @@ static struct pci_driver pcie_portdriver = {
 	.driver.pm 	= PCIE_PORTDRV_PM_OPS,
 };
 
+static int __init dmi_pcie_pme_disable_msi(const struct dmi_system_id *d)
+{
+	pr_notice("%s detected: will not use MSI for PCIe PME signaling\n",
+			d->ident);
+	pcie_pme_disable_msi();
+	return 0;
+}
+
+static struct dmi_system_id __initdata pcie_portdrv_dmi_table[] = {
+	/*
+	 * Boxes that should not use MSI for PCIe PME signaling.
+	 */
+	{
+	 .callback = dmi_pcie_pme_disable_msi,
+	 .ident = "MSI Wind U-100",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR,
+		     		"MICRO-STAR INTERNATIONAL CO., LTD"),
+		     DMI_MATCH(DMI_PRODUCT_NAME, "U-100"),
+		     },
+	 },
+	 {}
+};
+
 static int __init pcie_portdrv_init(void)
 {
 	int retval;
 
+	dmi_check_system(pcie_portdrv_dmi_table);
+
 	retval = pcie_port_bus_register();
 	if (retval) {
 		printk(KERN_WARNING "PCIE: bus_register error: %d\n", retval);