diff options
authorJean Delvare <khali@linux-fr.org>2011-09-16 21:24:02 +0200
committerGuenter Roeck <guenter.roeck@ericsson.com>2011-09-21 17:25:18 -0700
commita45a8c8571c0be6a6bd72ae5a14255c26b14b504 (patch)
parent6bf9e9b09c3abb5447bbbf16c2d0cbe721e44f3f (diff)
hwmon: (coretemp) Let the user force TjMax
On old CPUs (and even some recent Atom CPUs) TjMax can't be read from the CPU registers, so it is guessed by the driver using a complex heuristic which isn't reliable. So let users who know their CPU's TjMax pass it as a module parameter. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "R, Durgadoss" <durgadoss.r@intel.com> Cc: Guenter Roeck <guenter.roeck@ericsson.com> Cc: Alexander Stein <alexander.stein@systec-electronic.com> Acked-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
2 files changed, 19 insertions, 3 deletions
diff --git a/Documentation/hwmon/coretemp b/Documentation/hwmon/coretemp
index fa8776ab9b1..49c0d42dde8 100644
--- a/Documentation/hwmon/coretemp
+++ b/Documentation/hwmon/coretemp
@@ -49,9 +49,10 @@ tempX_label - Contains string "Core X", where X is processor
number. For Package temp, this will be "Physical id Y",
where Y is the package number.
-The TjMax temperature is set to 85 degrees C if undocumented model specific
-register (UMSR) 0xee has bit 30 set. If not the TjMax is 100 degrees C as
-(sometimes) documented in processor datasheet.
+On CPU models which support it, TjMax is read from a model-specific register.
+On other models, it is set to an arbitrary value based on weak heuristics.
+If these heuristics don't work for you, you can pass the correct TjMax value
+as a module parameter (tjmax).
Appendix A. Known TjMax lists (TBD):
Some information comes from ark.intel.com
diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index 256f70803eb..5a41e9dda90 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -36,11 +36,20 @@
#include <linux/cpu.h>
#include <linux/pci.h>
#include <linux/smp.h>
+#include <linux/moduleparam.h>
#include <asm/msr.h>
#include <asm/processor.h>
#define DRVNAME "coretemp"
+ * force_tjmax only matters when TjMax can't be read from the CPU itself.
+ * When set, it replaces the driver's suboptimal heuristic.
+ */
+static int force_tjmax;
+module_param_named(tjmax, force_tjmax, int, 0444);
+MODULE_PARM_DESC(tjmax, "TjMax value in degrees Celsius");
#define BASE_SYSFS_ATTR_NO 2 /* Sysfs Base attr no for coretemp */
#define NUM_REAL_CORES 16 /* Number of Real cores per cpu */
#define CORETEMP_NAME_LENGTH 17 /* String Length of attrs */
@@ -398,6 +407,12 @@ static int get_tjmax(struct cpuinfo_x86 *c, u32 id, struct device *dev)
+ if (force_tjmax) {
+ dev_notice(dev, "TjMax forced to %d degrees C by user\n",
+ force_tjmax);
+ return force_tjmax * 1000;
+ }
* An assumption is made for early CPUs and unreadable MSR.
* NOTE: the calculated value may not be correct.