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hwmon: (coretemp) Don't use threshold registers for tempX_max

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With commit c814a4c7c4, the meaning of tempX_max
was changed. It no longer returns the value of bits 8:15 of
MSR_IA32_TEMPERATURE_TARGET, but instead returns the value of CPU threshold
register T1. tempX_max_hyst was added to reflect the value of temperature
threshold register T0.

As it turns out, T0 and T1 are used on some systems, presumably by the BIOS.
Also, T0 and T1 don't have a well defined meaning. The thresholds may be used
as upper or lower limits, and it is not guaranteed that T0 <= T1. Thus, the new
attribute mapping does not reflect the actual usage of the threshold registers.
Also, register contents are changed during runtime by an entity other than the
hwmon driver, meaning the values cached by the driver do not reflect actual
register contents.

Revert most of c814a4c7c4 to address the problem.
Support for T0 and T1 will be added back in with a separate commit, using new
attribute names.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Guenter Roeck
2011-09-19 21:41:16 -07:00
parent a45a8c8571
commit f4af6fd6e2
2 changed files with 14 additions and 128 deletions
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7
Documentation/hwmon/coretemp
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@@ -35,13 +35,6 @@ the Out-Of-Spec bit. Following table summarizes the exported sysfs files:
All Sysfs entries are named with their core_id (represented here by 'X').
tempX_input - Core temperature (in millidegrees Celsius).
tempX_max - All cooling devices should be turned on (on Core2).
Initialized with IA32_THERM_INTERRUPT. When the CPU
temperature reaches this temperature, an interrupt is
generated and tempX_max_alarm is set.
tempX_max_hyst - If the CPU temperature falls below than temperature,
an interrupt is generated and tempX_max_alarm is reset.
tempX_max_alarm - Set if the temperature reaches or exceeds tempX_max.
Reset if the temperature drops to or below tempX_max_hyst.
tempX_crit - Maximum junction temperature (in millidegrees Celsius).
tempX_crit_alarm - Set when Out-of-spec bit is set, never clears.
Correct CPU operation is no longer guaranteed.