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, 27 insertions, 0 deletions

diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 13c8972886e..127e8f169d9 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/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);