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    ACPI: remove BM_RLD access from idle entry path · 31878dd8
    Len Brown 提交于
    It is true that BM_RLD needs to be set to enable
    bus master activity to wake an older chipset (eg PIIX4) from C3.
    
    This is contrary to the erroneous wording the ACPI 2.0, 3.0
    specifications that suggests that BM_RLD is an indicator
    rather than a control bit.
    
    ACPI 1.0's correct wording should be restored in ACPI 4.0:
    http://www.acpica.org/bugzilla/show_bug.cgi?id=689
    
    But the kernel should not have to clear BM_RLD
    when entering a non C3-type state just to set
    it again when entering a C3-type C-state.
    
    We should be able to set BM_RLD at boot time
    and leave it alone -- removing the overhead of
    accessing this IO register from the idle entry path.
    Signed-off-by: NLen Brown <len.brown@intel.com>
    31878dd8
processor_idle.c 48.2 KB