root/lm-sensors/trunk/doc/vid

Revision 4541, 3.7 kB (checked in by khali, 1 year ago)

Update doc/vid:
* We no longer use VRM 8.2 by default
* Update the sysfs paths
* Update the chip lists

  • Property svn:eol-style set to native
  • Property svn:keywords set to Author Date Id Revision
Line 
1 VID pin settings
2 --------------------
3
4 The VID (Voltage Identification) pins on sensor chips
5 are used to read the CPU Core voltage setting.
6
7 The VID setting can be controlled by jumpers on the board,
8 or, in newer motherboards, by settings in the BIOS.
9 On these newer boards, the BIOS programs some device's
10 pins which in turn controls a DC-DC Converter to set its
11 output to a certain voltage. These pins are also connected to
12 the sensor chip so that the VID setting can be read back
13 by applications.
14
15 There are generally 5 VID pins. Recent motherboards may use 6 pins.
16 The VID codes are defined by Intel in documents titled
17 "VRM X.X DC-DC Converter Design Guidelines".
18 (VRM = Voltage Regulator Module), or
19 "Voltage Regulator-Down (VRD) 10.0 Design Guide".
20 These documents are available at http://developer.intel.com.
21
22 There are several different VRM document versions.
23 The common versions are as follows:
24
25 Document Version        Voltage Range   Increment       Processors
26 ----------------        -------------   ---------       ----------
27 "2.4"                   0.8 - 1.55      0.025V          AMD Opteron 24x
28
29 8.2 (8.1, 8.3)          1.30 - 2.05V    0.05V           PII, PIII, Celeron
30                         2.1 - 3.5V      0.10V
31
32 8.4                     1.30 - 2.05V    0.05V           PIII, Celeron
33                                                         4 pins only
34
35 8.5                     1.050 - 1.825V  0.05V           PIII-S Tualatin
36
37 9.0, (9.1)              1.100 - 1.850V  0.025V          P4, AMD Socket A
38
39 10.0                    0.8375 - 1.6000 0.0125V         Desktop Socket 478
40
41
42 "2.4" is not an actual document version but simply a way to identify
43 AMD Opteron 24x processors.
44 Note that versions 8.1 - 8.4 are compatible.
45
46 lm_sensors versions through 2.6.3 support only the VRM 8.2 standard.
47
48 Starting in lm_sensors 2.6.4 the VRM version is configurable.
49 To configure the sensor chip for the correct voltage range,
50 you must set the "vrm" correctly either via /proc, /sys,  or sensors.conf.
51
52 To change the vrm version to 9.0, for example, do the following
53 after the chip module (in this example, w83781d) is loaded:
54
55         (kernel 2.4)
56             echo 9.0 > /proc/sys/dev/sensors/w83781d-isa-0290/vrm
57         (kernel 2.6 up to 2.6.13)
58             echo 90 > /sys/bus/i2c/devices/0-0290/vrm
59         (kernel 2.6.14 and later)
60             echo 90 > /sys/class/hwmon/hwmon0/device/vrm
61
62 Alternatively, add a line in /etc/sensors.conf in the w83781d section
63 (you should put this line BEFORE any line that uses vid in a calculation):
64
65         set vrm 9.0
66
67 and then, after the chip module is loaded, do:
68
69         sensors -s
70
71 After this, reading the vid either by
72
73         (kernel 2.4)
74             cat /proc/sys/dev/sensors/w83781d-isa-0290/vid
75         (kernel 2.6 up to 2.6.13 - divide the output by 1000)
76             cat /sys/bus/i2c/devices/0-0290/cpu0_vid
77         (kernel 2.6.14 and later - divide the output by 1000)
78             cat /sys/class/hwmon/hwmon0/device/cpu0_vid
79
80 or by
81
82         sensors
83
84 should show the new vid value.
85
86
87 The following values are legal vrm values. Other values will be
88 allowed but will result in using the 8.2 standard.
89
90         2.4, 8.1-8.5, 9.0, 9.1, 10.0
91
92
93 Remember, the VID pins on the sensor chips are inputs only.
94 That means they can't be changed and there shouldn't be
95 any problems if you experiment with the vrm values until you
96 get it right. You cannot manipulate the actual processor core
97 voltage through lm_sensors drivers.
98
99 Not all sensor chips have VID inputs.
100 For those that do, the VRM support status is listed below.
101
102 The following chip drivers support all the VRM versions via
103 /etc/sensors.conf and the vrm entry in /proc or /sys:
104
105         adm1025, adm1026, asb100, lm85, lm87, pc87360,
106         vt1211, vt8231, w83627ehf, w83627hf, w83781d, w83792d
107
108
109 The following chip drivers support only VRM 8.2 and cannot be changed:
110
111         adm1024, it87, mtp008, adm9240, gl520sm, lm78
112
113 If you have a board with one of these chips which needs advanced
114 VRM support please email us.
115
116 The following chip drivers support only VRM 10.0 and cannot be changed:
117
118         lm93
119
120 ------------------
121 Copyright (c) 2002-2004 Mark D. Studebaker
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