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    Subject[095/111] ACPI: Fix regression where _PPC is not read at boot even when ignore_ppc=0
    2.6.32-stable review patch.  If anyone has any objections, please let us know.


    From: Darrick J. Wong <>

    commit 455c0d71d46e86b0b7ff2c9dcfc19bc162302ee9 upstream.

    Earlier, Ingo Molnar posted a patch to make it so that the kernel would avoid
    reading _PPC on his broken T60. Unfortunately, it seems that with Thomas
    Renninger's patch last July to eliminate _PPC evaluations when the processor
    driver loads, the kernel never actually reads _PPC at all! This is problematic
    if you happen to boot your non-T60 computer in a state where the BIOS _wants_
    _PPC to be something other than zero.

    So, put the _PPC evaluation back into acpi_processor_get_performance_info if
    ignore_ppc isn't 1.

    Signed-off-by: Darrick J. Wong <>
    Signed-off-by: Len Brown <>
    Acked-by: Jeff Mahoney <>
    Signed-off-by: Greg Kroah-Hartman <>

    drivers/acpi/processor_perflib.c | 6 +++++-
    1 file changed, 5 insertions(+), 1 deletion(-)

    --- a/drivers/acpi/processor_perflib.c
    +++ b/drivers/acpi/processor_perflib.c
    @@ -356,7 +356,11 @@ static int acpi_processor_get_performanc
    if (result)
    goto update_bios;

    - return 0;
    + /* We need to call _PPC once when cpufreq starts */
    + if (ignore_ppc != 1)
    + result = acpi_processor_get_platform_limit(pr);
    + return result;

    * Having _PPC but missing frequencies (_PSS, _PCT) is a very good hint that

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      Last update: 2010-08-12 02:33    [W:3.563 / U:0.512 seconds]
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