[Bug 528741] [NEW] Sensors command is return an incorrect value for CPU_0 VID

[David Partington]

Public bug reported:

Binary package hint: linux-generic

I have a Biostar motherboard with the it8716 superio device.  When I
execute the sensors hardware monitor the VID values is incorrect.  In
researching this issue I found that the it87.c module was modified in
January 2009 because of bug #357766 to include support for  it8718 and
it8720 superio devices.  The introduction of this change has created the
issue.  A new definition. IT87_REG_VID           0x0a,  was created
because the it8718 and it8720 devices have a different offset for the
VID register than the rest of the it87xx devices. See the two sets of
definitions below:

          126 /* Logical device 7 registers (IT8712F and later) */
          127 #define IT87_SIO_GPIO3_REG      0x27
          128 #define IT87_SIO_GPIO5_REG      0x29
          129 #define IT87_SIO_PINX2_REG      0x2c    /* Pin selection */
          130 #define IT87_SIO_VID_REG        0xfc    /* VID value */

          161 /* The IT8718F and IT8720F have the VID value in a different register, in
          162    Super-I/O configuration space. */
          163 #define IT87_REG_VID           0x0a

When the logic was implemented to support these new devices the
incorrect definition was used in the code.  See below"

          1062                 if ((sio_data->type == it8718 || sio_data->type == it8720)
          1063                  && !(sio_data->skip_vid))
          1064                         sio_data->vid_value = superio_inb(IT87_SIO_VID_REG);
          1065

As you can see the original definition - IT87_SIO_VID_REG - was used
when the new definition - IT87_REG_VID - should have been used.

The inverse logic is also incorrect.  See below:

          1559                 /* The 8705 does not have VID capability.
          1560                    The 8718 and the 8720 don't use IT87_REG_VID for the
          1561                    same purpose. */
          1562                 if (data->type == it8712 || data->type == it8716) {
          1563                         data->vid = it87_read_value(data, IT87_REG_VID);
          1564                         /* The older IT8712F revisions had only 5 VID pins,
          1565                            but we assume it is always safe to read 6 bits. */
          1566                         data->vid &= 0x3f;
          1567                 }

Again, as you can see the incorrect definition was used for the it8712
and it8716 devices.  Plus comment is incorrect.  The definition -
IT87_REG_VID - was used when - IT87_SIO_VID_REG - should have been used.

Thus my suggest repair for this issue should be:

          1062                 if ((sio_data->type == it8718 || sio_data->type == it8720)
          1063                  && !(sio_data->skip_vid))
          1064                         sio_data->vid_value = superio_inb(IT87_REG_VID);
          1065

          1559                 /* The 8705 does not have VID capability.
          1560                    The 8718 and the 8720 don't use IT87_SIO_VID_REG for the
          1561                    same purpose. */
          1562                 if (data->type == it8712 || data->type == it8716) {
          1563                         data->vid = it87_read_value(data, IT87_SIO_VID_REG);
          1564                         /* The older IT8712F revisions had only 5 VID pins,
          1565                            but we assume it is always safe to read 6 bits. */
          1566                         data->vid &= 0x3f;
          1567                 }

ProblemType: Bug
Architecture: amd64
Date: Fri Feb 26 16:19:48 2010
DistroRelease: Ubuntu 9.10
ExecutablePath: /usr/bin/yelp
NonfreeKernelModules: nvidia
Package: yelp 2.28.0-0ubuntu2
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-20.57-generic
SourcePackage: yelp
Uname: Linux 2.6.31-20-generic x86_64

** Affects: linux-meta (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: hwmon it87 kernel

-- 
Sensors command is return an incorrect value for CPU_0 VID
https://bugs.launchpad.net/bugs/528741
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