1 files changed, 39 insertions, 0 deletions

diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c
index b7494af1e4a9..37a8fc92b44a 100644
--- a/drivers/hwmon/fam15h_power.c
+++ b/drivers/hwmon/fam15h_power.c
@@ -122,6 +122,38 @@ static bool __devinit fam15h_power_is_internal_node0(struct pci_dev *f4)
         return true;
 }
 
+/*
+ * Newer BKDG versions have an updated recommendation on how to properly
+ * initialize the running average range (was: 0xE, now: 0x9). This avoids
+ * counter saturations resulting in bogus power readings.
+ * We correct this value ourselves to cope with older BIOSes.
+ */
+static void __devinit tweak_runavg_range(struct pci_dev *pdev)
+{
+        u32 val;
+        const struct pci_device_id affected_device = {
+                PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) };
+
+        /*
+         * let this quirk apply only to the current version of the
+         * northbridge, since future versions may change the behavior
+         */
+        if (!pci_match_id(&affected_device, pdev))
+                return;
+
+        pci_bus_read_config_dword(pdev->bus,
+                PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
+                REG_TDP_RUNNING_AVERAGE, &val);
+        if ((val & 0xf) != 0xe)
+                return;
+
+        val &= ~0xf;
+        val |=  0x9;
+        pci_bus_write_config_dword(pdev->bus,
+                PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
+                REG_TDP_RUNNING_AVERAGE, val);
+}
+
 static void __devinit fam15h_power_init_data(struct pci_dev *f4,
                                              struct fam15h_power_data *data)
 {
@@ -155,6 +187,13 @@ static int __devinit fam15h_power_probe(struct pci_dev *pdev,
         struct device *dev;
         int err;
 
+        /*
+         * though we ignore every other northbridge, we still have to
+         * do the tweaking on _each_ node in MCM processors as the counters
+         * are working hand-in-hand
+         */
+        tweak_runavg_range(pdev);
+
         if (!fam15h_power_is_internal_node0(pdev)) {
                 err = -ENODEV;
                 goto exit;