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hwmon: (adm1021) Clarify documentation regarding Xeon processors 

Recent Xeon processor thermal sensors are supported by the coretemp
driver and not the adm1021 driver. Only one old generation of Xeon
processors (the first Netburst ones) are supported by the adm1021
driver.

Reported-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
This commit is contained in:
Jean Delvare 2011-04-29 16:33:36 +02:00 committed by Jean Delvare
parent 177e75925b
commit d7ce0335b5
2 changed files with 20 additions and 19 deletions
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36
Documentation/hwmon/adm1021
View File

@ -14,10 +14,6 @@ Supported chips:
Prefix: 'gl523sm'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet:
* Intel Xeon Processor
Prefix: - any other - may require 'force_adm1021' parameter
Addresses scanned: none
Datasheet: Publicly available at Intel website
* Maxim MAX1617
Prefix: 'max1617'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
@ -91,21 +87,27 @@ will do no harm, but will return 'old' values. It is possible to make
ADM1021-clones do faster measurements, but there is really no good reason
for that.
Xeon support
------------
Some Xeon processors have real max1617, adm1021, or compatible chips
within them, with two temperature sensors.
Netburst-based Xeon support
---------------------------
Other Xeons have chips with only one sensor.
Some Xeon processors based on the Netburst (early Pentium 4, from 2001 to
2003) microarchitecture had real MAX1617, ADM1021, or compatible chips
within them, with two temperature sensors. Other Xeon processors of this
era (with 400 MHz FSB) had chips with only one temperature sensor.
If you have a Xeon, and the adm1021 module loads, and both temperatures
appear valid, then things are good.
If you have such an old Xeon, and you get two valid temperatures when
loading the adm1021 module, then things are good.
If the adm1021 module doesn't load, you should try this:
modprobe adm1021 force_adm1021=BUS,ADDRESS
ADDRESS can only be 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e.
If nothing happens when loading the adm1021 module, and you are certain
that your specific Xeon processor model includes compatible sensors, you
will have to explicitly instantiate the sensor chips from user-space. See
method 4 in Documentation/i2c/instantiating-devices. Possible slave
addresses are 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e. It is likely that
only temp2 will be correct and temp1 will have to be ignored.
If you have dual Xeons you may have appear to have two separate
adm1021-compatible chips, or two single-temperature sensors, at distinct
addresses.
Previous generations of the Xeon processor (based on Pentium II/III)
didn't have these sensors. Next generations of Xeon processors (533 MHz
FSB and faster) lost them, until the Core-based generation which
introduced integrated digital thermal sensors. These are supported by
the coretemp driver.

3
drivers/hwmon/Kconfig
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@ -110,8 +110,7 @@ config SENSORS_ADM1021
help
If you say yes here you get support for Analog Devices ADM1021
and ADM1023 sensor chips and clones: Maxim MAX1617 and MAX1617A,
Genesys Logic GL523SM, National Semiconductor LM84, TI THMC10,
and the XEON processor built-in sensor.
Genesys Logic GL523SM, National Semiconductor LM84 and TI THMC10.
This driver can also be built as a module. If so, the module
will be called adm1021.