[Bugme-new] [Bug 12389] New: acpi-cpufreq doesn't detect speed limit when cold booted on battery

[bugme-daemon at bugzilla.kernel.org]

http://bugzilla.kernel.org/show_bug.cgi?id=12389

           Summary: acpi-cpufreq doesn't detect speed limit when cold booted
                    on battery
           Product: Power Management
           Version: 2.5
     KernelVersion: 2.6.27
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
        AssignedTo: cpufreq at vger.kernel.org
        ReportedBy: theholyettlz at googlemail.com


Latest working kernel version: 2.6.26?
Earliest failing kernel version: 2.6.27.10-167.fc10 (perhaps some earlier)
Distribution: Fedora 10
Hardware Environment: x86-64, Clevo M720R notebook with Intel Core 2 Duo T8100
processor, X3100 graphics
Software Environment: x86-64

Problem Description:
When on battery power, my notebook's BIOS specifies that the maximum CPU speed
should be 1.2 GHz. But immediately after booting on battery, acpi-cpufreq
thinks the maximum speed is 2.101 GHz (what it should be on mains power).
Switching briefly to mains, or pressing the "power save" button (which imposes
a 1.2 GHz limit when on mains), seems to kick it all into place and thereafter
the limit is 1.2 GHz on battery, 2.101 on mains.

Steps to reproduce:
1. Cold boot on battery power.
2. Observe CPU will scale up to 2.101 GHz.
3. Briefly switch to mains or press power-save button.
4. Note maximum frequency on battery is now 1.2 GHz.


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