lkml.org 
[lkml]   [2010]   [May]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3/8] x86/apic: allow use of lapic timer early calibration result
    Date
    From: Jacob Pan <jacob.jun.pan@intel.com>

    lapic timer calibration can be combined with tsc in platform specific
    calibration functions. if such calibration result is obtained early,
    we can skip the redundent calibration loops.

    Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
    Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    ---
    arch/x86/kernel/apic/apic.c | 21 ++++++++++++++++++++-
    1 files changed, 20 insertions(+), 1 deletions(-)

    diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
    index e5a4a1e..8ef56ac 100644
    --- a/arch/x86/kernel/apic/apic.c
    +++ b/arch/x86/kernel/apic/apic.c
    @@ -175,7 +175,7 @@ static struct resource lapic_resource = {
    .flags = IORESOURCE_MEM | IORESOURCE_BUSY,
    };

    -static unsigned int calibration_result;
    +unsigned int calibration_result;

    static int lapic_next_event(unsigned long delta,
    struct clock_event_device *evt);
    @@ -597,6 +597,25 @@ static int __init calibrate_APIC_clock(void)
    long delta, deltatsc;
    int pm_referenced = 0;

    + /**
    + * check if lapic timer has already been calibrated by platform
    + * specific routine, such as tsc calibration code. if so, we just fill
    + * in the clockevent structure and return.
    + */
    +
    + if (calibration_result) {
    + apic_printk(APIC_VERBOSE, "lapic timer already calibrated %d\n",
    + calibration_result);
    + lapic_clockevent.mult = div_sc(calibration_result/APIC_DIVISOR,
    + TICK_NSEC, lapic_clockevent.shift);
    + lapic_clockevent.max_delta_ns =
    + clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
    + lapic_clockevent.min_delta_ns =
    + clockevent_delta2ns(0xF, &lapic_clockevent);
    + lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
    + return 0;
    + }
    +
    local_irq_disable();

    /* Replace the global interrupt handler */
    --
    1.6.3.3


    \
     
     \ /
      Last update: 2010-05-07 19:51    [W:4.225 / U:0.336 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site