PCI/PM: Do not use native PCIe PME by default

Commit c7f486567c1d0acd2e4166c47069835b9f75e77b
(PCI PM: PCIe PME root port service driver) causes the native PCIe
PME signaling to be used by default, if the BIOS allows the kernel to
control the standard configuration registers of PCIe root ports.
However, the native PCIe PME is coupled to the native PCIe hotplug
and calling pcie_pme_acpi_setup() makes some BIOSes expect that
the native PCIe hotplug will be used as well.  That, in turn, causes
problems to appear on systems where the PCIe hotplug driver is not
loaded.  The usual symptom, as reported by Jaroslav Kameník and
others, is that the ACPI GPE associated with PCIe hotplug keeps
firing continuously causing kacpid to take substantial percentage
of CPU time.

To work around this issue, change the default so that the native
PCIe PME signaling is only used if directly requested with the help
of the pcie_pme= command line switch.

Fixes https://bugzilla.kernel.org/show_bug.cgi?id=15924 , which is
a listed regression from 2.6.33.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-by: Jaroslav Kameník <jaroslav@kamenik.cz>
Tested-by: Antoni Grzymala <antekgrzymala@gmail.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1808f1157f30ae5a187f4a8783d973875cd675dd..82d6aeb5228ff62d71a64e04519c24f35a6116e0 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2048,7 +2048,9 @@ and is between 256 and 4096 characters. It is defined in the file
                        WARNING: Forcing ASPM on may cause system lockups.
 
        pcie_pme=       [PCIE,PM] Native PCIe PME signaling options:
-               off     Do not use native PCIe PME signaling.
+                       Format: {auto|force}[,nomsi]
+               auto    Use native PCIe PME signaling if the BIOS allows the
+                       kernel to control PCIe config registers of root ports.
                force   Use native PCIe PME signaling even if the BIOS refuses
                        to allow the kernel to control the relevant PCIe config
                        registers.

diff --git a/drivers/pci/pcie/pme/pcie_pme.c b/drivers/pci/pcie/pme/pcie_pme.c
index aac285a16b62bec0f84690c5241c4ee82185e383..d672a0a638162328a22027005c0b2309d5c00370 100644 (file)
--- a/drivers/pci/pcie/pme/pcie_pme.c
+++ b/drivers/pci/pcie/pme/pcie_pme.c
@@ -34,7 +34,7 @@
  * being registered.  Consequently, the interrupt-based PCIe PME signaling will
  * not be used by any PCIe root ports in that case.
  */
-static bool pcie_pme_disabled;
+static bool pcie_pme_disabled = true;
 
 /*
  * The PCI Express Base Specification 2.0, Section 6.1.8, states the following:
@@ -64,12 +64,19 @@ 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"))
+       if (!strncmp(str, "auto", 4))
+               pcie_pme_disabled = false;
+       else if (!strncmp(str, "force", 5))
                pcie_pme_force_enable = true;
-       else if (!strcmp(str, "nomsi"))
-               pcie_pme_msi_disabled = true;
+
+       str = strchr(str, ',');
+       if (str) {
+               str++;
+               str += strspn(str, " \t");
+               if (*str && !strcmp(str, "nomsi"))
+                       pcie_pme_msi_disabled = true;
+       }
+
        return 1;
 }
 __setup("pcie_pme=", pcie_pme_setup);