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x86_64: remove pit synchronization 

The APIC timer setup code synchronizes the local APIC timer to the
PIT/HPET. This is pointless as the PIT and the local APIC timer
frequency are not correlated and the APIC timer calibration can never
be accurate enough to avoid that the local APIC timer and the PIT/HPET
drift apart.

Simply remove it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
This commit is contained in:
Thomas Gleixner 2007-10-12 23:04:06 +02:00 committed by Thomas Gleixner
parent 801740971a
commit 500ff08b76
1 changed files with 0 additions and 18 deletions
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18
arch/x86/kernel/apic_64.c
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@ -790,24 +790,6 @@ static void setup_APIC_timer(unsigned int clocks)
local_irq_save(flags);
/* wait for irq slice */
if (hpet_address && hpet_use_timer) {
u32 trigger = hpet_readl(HPET_T0_CMP);
while (hpet_readl(HPET_T0_CMP) == trigger)
/* do nothing */ ;
} else {
int c1, c2;
outb_p(0x00, 0x43);
c2 = inb_p(0x40);
c2 |= inb_p(0x40) << 8;
do {
c1 = c2;
outb_p(0x00, 0x43);
c2 = inb_p(0x40);
c2 |= inb_p(0x40) << 8;
} while (c2 - c1 < 300);
}
irqen = ! cpu_isset(smp_processor_id(),
timer_interrupt_broadcast_ipi_mask);
__setup_APIC_LVTT(clocks, 0, irqen);