preliminary programmable VRM version support in w83781d.

      Replace VID_FROM_REG() with vid_from_reg() in new sensors_vid.h.
      Update library so it can be set in sensors.conf.
      Add new documentation. Update mkpatch for new file.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@1352 7894878c-1315-0410-8ee3-d5d059ff63e0

1 files changed, 97 insertions, 0 deletions

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+VID pin settings
+--------------------
+
+The VID (Voltage Identification) pins on sensor chips
+are used to read the CPU Core voltage setting.
+
+The VID setting can be controlled by jumpers on the board,
+or, in newer motherboards, by settings in the BIOS.
+On these newer boards, the BIOS programs some device's
+pins which in turn controls a DC-DC Converter to set its
+output to a certain voltage. These pins are also connected to
+the sensor chip so that the VID setting can be read back
+by applications.
+
+There are generally 5 VID pins. The VID codes are defined
+by Intel in documents titled
+"VRM X.X DC-DC Converter Design Guidelines".
+(VRM = Voltage Regulator Module)
+These documents are available at http://developer.intel.com.
+
+There are several different VRM document versions.
+The common versions are as follows:
+
+Document Version	Voltage Range	Increment	Processors
+----------------	-------------	---------	----------
+8.2 (8.1, 8.3)		1.30 - 2.05V    0.05V		PII, PIII, Celeron
+			2.1 - 3.5V	0.10V
+
+8.4			1.30 - 2.05V    0.05V		PIII, Celeron
+							4 pins only
+
+8.5			1.050 - 1.825V	0.05V		PIII-S Tualatin
+
+9.0, (9.1)		1.100 - 1.850V	0.025V		PIV, AMD Socket A
+
+
+Note that versions 8.1 - 8.4 are compatible.
+
+lm_sensors versions through 2.6.3 support only the VRM 8.2 standard.
+
+Starting in lm_sensors 2.6.4 the VRM version is configurable.
+To configure the sensor chip for the correct voltage range,
+you must set the "vrm" correctly either via /proc or sensors.conf.
+
+To be compatible with previous lm_sensors versions, the vrm defaults
+to version 8.2.
+
+To change the vrm version to 9.0, for example, do the following
+after the chip module (in this example, w83781d) is loaded:
+
+	echo 9.0 > /proc/sys/dev/sensors/w83781d-isa-0290/vrm
+
+Alternatively, add a line in /etc/sensors.conf in the w83781d section:
+
+	set vrm 9.0
+
+and then, after the chip module is loaded, do:
+
+	sensors -s
+
+After this, reading the vid either by
+
+	cat /proc/sys/dev/sensors/w83781d-isa-0290/vid
+
+or by
+
+	sensors
+
+should show the new vid value.
+
+
+The following values are legal vrm values:
+
+	8.2, 8.4, 8.5, 9.0
+
+
+Remember, the VID pins on the sensor chips are inputs only.
+That means they can't be changed and there shouldn't be
+any problems if you experiment with the vrm values until you
+get it right.
+
+
+Not all sensor chips have VID inputs.
+For those that do, the VRM support status is listed below.
+
+The following chip drivers support all the VRM versions via
+/etc/sensors.conf and the vrm entry in /proc:
+
+	adm1024, adm1025, it87, lm87, mtp008, w83781d
+
+
+The following chip drivers support only VRM 8.2 and cannot be changed:
+
+	adm9240, gl520sm, lm78, maxilife
+
+If you have a board with one of these chips which needs advanced
+VRM support please email us.