Eric Lee / smarc-fsl-linux-kernel

07 Feb, 2009

1 commit

  • d96f94c60   ACPI: Enable bit 11 in _PDC to advertise hw coord ... Browse Code »

    Bit 11 in intel PDC definitions is meant for OS capability to handle
    hardware coordination of P-states. In Linux we have always supported
    hwardware coordination of P-states. Just let the BIOSes know that we
    support it, by setting this bit.

    Some BIOSes use this bit to choose between hardware or software coordination
    and without this change below, BIOSes switch to software coordination, which
    is not very optimal in terms of power consumption and extra wakeups from idle.

    Signed-off-by: Venkatesh Pallipadi
    Signed-off-by: Len Brown

    Pallipadi, Venkatesh
     

14 Oct, 2006

1 commit

  • 991528d73   ACPI: Processor native C-states using MWAIT ... Browse Code »

    Intel processors starting with the Core Duo support
    support processor native C-state using the MWAIT instruction.
    Refer: Intel Architecture Software Developer's Manual
    http://www.intel.com/design/Pentium4/manuals/253668.htm

    Platform firmware exports the support for Native C-state to OS using
    ACPI _PDC and _CST methods.
    Refer: Intel Processor Vendor-Specific ACPI: Interface Specification
    http://www.intel.com/technology/iapc/acpi/downloads/302223.htm

    With Processor Native C-state, we use 'MWAIT' instruction on the processor
    to enter different C-states (C1, C2, C3). We won't use the special IO
    ports to enter C-state and no SMM mode etc required to enter C-state.
    Overall this will mean better C-state support.

    One major advantage of using MWAIT for all C-states is, with this and
    "treat interrupt as break event" feature of MWAIT, we can now get accurate
    timing for the time spent in C1, C2, .. states.

    Signed-off-by: Venkatesh Pallipadi
    Signed-off-by: Andrew Morton
    Signed-off-by: Len Brown

    Venkatesh Pallipadi
     

09 Feb, 2006

1 commit

01 Dec, 2005

1 commit

  • 05131ecc9   [ACPI] Avoid BIOS inflicted crashes by evaluating _PDC only once ... Browse Code »

    Linux invokes the AML _PDC method (Processor Driver Capabilities)
    to tell the BIOS what features it can handle. While the ACPI
    spec says nothing about the OS invoking _PDC multiple times,
    doing so with changing bits seems to hopelessly confuse the BIOS
    on multiple platforms up to and including crashing the system.

    Factor out the _PDC invocation so Linux invokes it only once.

    http://bugzilla.kernel.org/show_bug.cgi?id=5483

    Signed-off-by: Venkatesh Pallipadi
    Signed-off-by: Len Brown

    Venkatesh Pallipadi
     

05 Aug, 2005

1 commit

12 Jul, 2005

1 commit