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    ACPI: processor: idle: fix lockup regression on 32-bit ThinkPad T40 · bfe55a1f
    Woody Suwalski authored
    Add and ACPI idle power level limit for 32-bit ThinkPad T40.
    
    There is a regression on T40 introduced by commit d6b88ce2, starting
    with kernel 5.16:
    
    commit d6b88ce2
    Author: Richard Gong <richard.gong@amd.com>
    Date:   Wed Sep 22 08:31:16 2021 -0500
    
      ACPI: processor idle: Allow playing dead in C3 state
    
    The above patch is trying to enter C3 state during init, what is causing
    a T40 system freeze. I have not found a similar issue on any other of my
    32-bit machines.
    
    The fix is to add another exception to the processor_power_dmi_table[] list.
    As a result the dmesg shows as expected:
    
    [2.155398] ACPI: IBM ThinkPad T40 detected - limiting to C2 max_cstate. Override with "processor.max_cstate=9"
    [2.155404] ACPI: processor limited to max C-state 2
    
    The fix is trivial and affects only vintage T40 systems.
    
    Fixes: d6b88ce2 ("CPI: processor idle: Allow playing dead in C3 state")
    Signed-off-by: default avatarWoody Suwalski <wsuwalski@gmail.com>
    Reviewed-by: default avatarHans de Goede <hdegoede@redhat.com>
    Cc: 5.16+ <stable@vger.kernel.org> # 5.16+
    [ rjw: New subject ]
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    bfe55a1f
processor_idle.c 35.4 KB