[lm-sensors] hwmon: (adm1021) Clarify documentation regarding Xeon processors

[Darren Hart]

On 04/09/2011 01:39 PM, Guenter Roeck wrote:
> On Sat, Apr 09, 2011 at 12:31:56PM -0400, Jean Delvare wrote:
>> 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.

In addition to changing the kernel config help, is there a way to avoid
loading this driver for non netburst type CPUs? Someway to blacklist
later CPUs from using this driver? Seems this would make sensors-detect
and such behave better.

Thanks,

Darren

>>
>> Reported-by: Darren Hart <dvhart at linux.intel.com>
>> Signed-off-by: Jean Delvare <khali at linux-fr.org>
> 
> Nitpick below, otherwise
> 
> Acked-by: Guenter Roeck <guenter.roeck at ericsson.com>
> 
>> ---
>>  Documentation/hwmon/adm1021 |   36 +++++++++++++++++++-----------------
>>  drivers/hwmon/Kconfig       |    3 +--
>>  2 files changed, 20 insertions(+), 19 deletions(-)
>>
>> --- linux-2.6.39-rc2.orig/Documentation/hwmon/adm1021	2010-08-02 00:11:14.000000000 +0200
>> +++ linux-2.6.39-rc2/Documentation/hwmon/adm1021	2011-04-08 10:11:13.000000000 +0200
>> @@ -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' v
>>  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, are you are certain
> 
> 		are you are -> and you are
> 
>> +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.
>> --- linux-2.6.39-rc2.orig/drivers/hwmon/Kconfig	2011-04-07 18:51:51.000000000 +0200
>> +++ linux-2.6.39-rc2/drivers/hwmon/Kconfig	2011-04-08 09:36:50.000000000 +0200
>> @@ -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.
>>
>>
>> -- 
>> Jean Delvare
>>
>> _______________________________________________
>> lm-sensors mailing list
>> lm-sensors at lm-sensors.org
>> http://lists.lm-sensors.org/mailman/listinfo/lm-sensors

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel