[Bugme-janitors] [Bug 10699] New: Wrong battery information on MSI S271 laptop with msi-laptop module loaded

[bugme-daemon at bugzilla.kernel.org]

http://bugzilla.kernel.org/show_bug.cgi?id=10699

           Summary: Wrong battery information on MSI S271 laptop with msi-
                    laptop module loaded
           Product: Drivers
           Version: 2.5
     KernelVersion: v2.6.26-rc2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: low
          Priority: P1
         Component: Other
        AssignedTo: drivers_other at kernel-bugs.osdl.org
        ReportedBy: mike.trim at gmail.com


Latest working kernel version: cfc94cdf8e0f14e692a5a40ef3cc10f464b2511b (after
v2.6.22)
Earliest failing kernel version: 4f5c791a850e5305a5b1b48d0e4b4de248dc96f9
(before v2.6.23-rc1)
Distribution: Ubuntu 8.04 (Hardy Heron)
Hardware Environment: MSI S271 laptop (MS-1058)
Software Environment: clean install
Problem Description:

Ubuntu bug: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/218094

On an MSI S271 laptop (aka MS-1058), the battery state is reported incorrectly
after the msi-laptop module is loaded.

e.g. (with battery fully charged) 
$ cat /proc/acpi/battery/BAT1/state

Correct behaviour:
remaining capacity: 3670 mAh

After msi-laptop loaded:
remaining capacity:      526 mAh  (reported values are not consistent)
or sometimes:
remaining capacity:      unknown

See the Ubuntu bug
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/218094) for more detailed
output.


I have run git bisect which tracked this down to:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4f5c791a850e5305a5b1b48d0e4b4de248dc96f9
commit 4f5c791a850e5305a5b1b48d0e4b4de248dc96f9 
Author: Lennart Poettering <mzxreary at 0pointer.de>
Date: Tue May 8 22:07:02 2007 +0200

    DMI-based module autoloading

This patch causes the msi-laptop module to be automatically loaded on laptops
that are (supposed to be) supported by the msi-laptop module.  With this commit
the msi-laptop module is automatically loaded as expected:
 msi-laptop: Identified laptop model 'MSI S271'.
 msi-laptop: driver 0.5 successfully loaded.


I have verified that blacklisting the msi-laptop module restores the correct
battery status on a clean boot.  If the module is subsequently loaded then the
battery status again reports incorrect values.  However, removing the module
after it has been loaded does not restore the battery state to the correct
values.


This behaviour occurs on all kernel versions after this commit (up to
v2.6.26-rc2 tested), on both amd64 and i386.


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