xeon doc update w/ help from P.P.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@2129 7894878c-1315-0410-8ee3-d5d059ff63e0

doc/chips/adm1021

@@ -17,7 +17,8 @@ Supported chips:
     Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e (inclusive)
     Datasheet:
   * Intel Xeon Processor
-    Prefix - any other - requires 'force_adm1021' parameter - see MODPARMS file
+    Prefix - any other - may require 'force_adm1021' parameter -
+    see MODPARMS and xeontemp files for more information
     Addresses scanned: none
     Datasheet: Publicly available at Intel website
     Status: Alpha, untested.
@@ -132,13 +133,24 @@ for that.
 
 Xeon support
 ------------
-The Xeon support is untested.
-The Xeon has only one sensor where the other devices have two.
-Use 'force_adm1021=BUS,ADDRESS' as a modprobe parameter.
-ADDRESS can only be 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e.
-The driver will report two temperatures but one will be invalid.
-It is not clear if all Xeon processors have this feature.
-Please report results.
+Some Xeon processors have real max1617, adm1021, or compatible chips
+with in them, with two temperature sensors.
+
+Other Xeons have chips with only one sensor.
+
+If you have a Xeon, and the adm1021 module loads, and both
+temperatures appear valid, then things are good.
+
+If the adm1021 module doesn't load, you should try two things:
+	1) modprobe adm1021 force_adm1021=BUS,ADDRESS
+	ADDRESS can only be 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e.
+	See if you have one or two valid temperatures
+
+	2) modprobe xeontemp
+	See if you have one valid temperature.
+
+Pick the best module for your processor based on the results.
+See the xeontemp documentation for further information.
 
 
 Chip Features

doc/chips/xeontemp

@@ -7,7 +7,8 @@ Supported chips:
   * Intel Xeon and other processors
     Prefix `xeontemp'
     Addresses scanned: I2C 0x18, 0x1a, 0x29, 0x2b, 0x4c, 0x4e
-    Datasheet: Publicly available at the Intel website
+    Datasheets: Publicly available at the Intel website
+                See the adm1021 document for additional references
 
 Authors: Frodo Looijaard <frodol@dds.nl>,Philip Edelbrock
         <phil@netroedge.com>, and Mark D. Studebaker (mdsxyz123@yahoo.com)
@@ -38,20 +39,67 @@ Module Parameters
 Description
 -----------
 
-Xeon and other Intel processors with an embedded i2c temperature
-sensor look very similar to an adm1021.
-The Xeon has only one sensor where the adm1021 has two.
-Not all Xeon processors have this feature.
-If you have an Intel processor, and sensors-detect recommended
+Many Xeons and other Intel processors have an embedded i2c temperature
+sensor that look very similar to an adm1021 or max1617.
+
+Some Xeons have honest to goodness, real live, actual MAX1617 chips on 
+them.  Others Xeons made around the same time have other ADM1021 
+compatible chips on them.  They are mounted on the CPU substrate along 
+with the processor information EEPROM that is part of that generation of 
+Xeon CPU's.
+
+So it's basically impossible to tell a Xeon TEMP sensor from a MAX1617 
+since they are in fact the same chip.  The Xeon Temperature sensors spec 
+is just a stripped down register spec for the ADM1021 that says the 
+"on-board" or "built-in" sensor registers are "reserved".  That way 
+Intel could substitute whatever ADM1021 compatible chip was cheapest at 
+the time when they built the CPU's.
+
+One reason to use the xeontemp driver is if, when Intel built your 
+particular Xeon's, they didn't use any of the ADM1021 compatible chips 
+that the ADM1021 driver recognizes.  In that case, using the xeontemp 
+driver will get you the temperatures you want without potentially 
+messing up something in the sensor.
+
+Another reason is to avoid having 'sensors' report the second
+temperature.
+
+Unfortunately, the 533MHz FSB Xeon's, dropped the on-board sensor chip. 
+So these new Xeons require a sensor on the motherboard to be connected 
+to the thermal diode to read the temperature.  But these 533MHz capable 
+motherboards can also accept 400MHz CPU's with the on-board sensor so it 
+gets confusing in a hurry for motherboard vendors and users.
+
+If you have 400MHz FSB P4 Xeon CPU's, you should have an on-CPU ADM1021 
+compatible sensor at 0x18 or 0x19.  In that case, use the ADM1021 driver 
+if it detects a chip at that address.  The CPU DIE temperature (Tj) will 
+be the "REMOTE" temperature from this sensor.  The "Board" or "built-in" 
+temperature from the ADM1021 will be the temperature of the ADM1021 
+compatible itself which is one of the chips you see on the side of the CPU.
+
+If you have sensors at 0x18 and 0x19 that are not detected by the 
+ADM1021, and you have 400MHz Xeons, then you may want to try the 
+xeontemp driver.
+
+If you have 533MHZ FSB Xeons, then you do *not* have an on-board thermal 
+sensor and you should look for CPU temperatures from the other sensors 
+on your motherboard. (Winbond chip for example).
+
+If you have an Intel Xeon processor, and sensors-detect recommended
 the adm1021 driver, and the address is one of
 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e, and when using the
 adm1021 driver, temp1 is invalid but temp2 looks correct, then
-it is likely you should use this driver instead.
+it is likely you should use the xeontemp driver instead.
+
+In summary, the xeontemp module supports one temperature and the 
+adm1021 module supports two. Use the module that works best for you.
 
 See the adm1021 documentation for more information.
 
+
 Author/Maintainer
 -----------------
 Mark D. Studebaker (mdsxyz123@yahoo.com).
 Derived from the adm1021 driver.
+Thanks to Philip Pokorny for help with this document.
 Send requests to the sensors@stimpy.netroedge.com mailing list.