hwmon: fam15h_power: fix bogus values with current BIOSes

Newer BKDG[1] versions recommend a different initialization value for the running average range register in the northbridge. This improves the power reading by avoiding counter saturations resulting in bogus values for anything below about 80% of TDP power consumption. Updated BIOSes will have this new value set up from the beginning, but meanwhile we correct this value ourselves. This needs to be done on all northbridges, even on those where the driver itself does not register at. This fixes the driver on all current machines to provide proper values for idle load. [1] http://support.amd.com/us/Processor_TechDocs/42301_15h_Mod_00h-0Fh_BKDG.pdf Chapter 3.8: D18F5xE0 Processor TDP Running Average (p. 452) Signed-off-by: Andre Przywara <andre.przywara@amd.com> Acked-by: Jean Delvare <khali@linux-fr.org> [guenter.roeck@ericsson.com: Removed unnecessary return statement] Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: stable@vger.kernel.org # 3.0+

hwmon: fam15h_power: fix bogus values with current BIOSes
Newer BKDG[1] versions recommend a different initialization value for the running average range register in the northbridge. This improves the power reading by avoiding counter saturations resulting in bogus values for anything below about 80% of TDP power consumption. Updated BIOSes will have this new value set up from the beginning, but meanwhile we correct this value ourselves. This needs to be done on all northbridges, even on those where the driver itself does not register at. This fixes the driver on all current machines to provide proper values for idle load. [1] http://support.amd.com/us/Processor_TechDocs/42301_15h_Mod_00h-0Fh_BKDG.pdf Chapter 3.8: D18F5xE0 Processor TDP Running Average (p. 452) Signed-off-by: Andre Przywara <andre.przywara@amd.com> Acked-by: Jean Delvare <khali@linux-fr.org> [guenter.roeck@ericsson.com: Removed unnecessary return statement] Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: stable@vger.kernel.org # 3.0+
Andre Przywara · Guenter Roeck
1 parent e816b57a33
Showing 1 changed file with 39 additions and 0 deletions Side-by-side Diff
drivers/hwmon/fam15h_power.c
@@ -122,6 +122,38 @@
 	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)
 {
@@ -154,6 +186,13 @@
 	struct fam15h_power_data *data;
 	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;
...	...	@@ -122,6 +122,38 @@
122	122	return true;
123	123	}
124	124
	125	+/*
	126	+ * Newer BKDG versions have an updated recommendation on how to properly
	127	+ * initialize the running average range (was: 0xE, now: 0x9). This avoids
	128	+ * counter saturations resulting in bogus power readings.
	129	+ * We correct this value ourselves to cope with older BIOSes.
	130	+ */
	131	+static void __devinit tweak_runavg_range(struct pci_dev *pdev)
	132	+{
	133	+ u32 val;
	134	+ const struct pci_device_id affected_device = {
	135	+ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) };
	136	+
	137	+ /*
	138	+ * let this quirk apply only to the current version of the
	139	+ * northbridge, since future versions may change the behavior
	140	+ */
	141	+ if (!pci_match_id(&affected_device, pdev))
	142	+ return;
	143	+
	144	+ pci_bus_read_config_dword(pdev->bus,
	145	+ PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
	146	+ REG_TDP_RUNNING_AVERAGE, &val);
	147	+ if ((val & 0xf) != 0xe)
	148	+ return;
	149	+
	150	+ val &= ~0xf;
	151	+ val \|= 0x9;
	152	+ pci_bus_write_config_dword(pdev->bus,
	153	+ PCI_DEVFN(PCI_SLOT(pdev->devfn), 5),
	154	+ REG_TDP_RUNNING_AVERAGE, val);
	155	+}
	156	+
125	157	static void __devinit fam15h_power_init_data(struct pci_dev *f4,
126	158	struct fam15h_power_data *data)
127	159	{
...	...	@@ -154,6 +186,13 @@
154	186	struct fam15h_power_data *data;
155	187	struct device *dev;
156	188	int err;
	189	+
	190	+ /*
	191	+ * though we ignore every other northbridge, we still have to
	192	+ * do the tweaking on _each_ node in MCM processors as the counters
	193	+ * are working hand-in-hand
	194	+ */
	195	+ tweak_runavg_range(pdev);
157	196
158	197	if (!fam15h_power_is_internal_node0(pdev)) {
159	198	err = -ENODEV;