Commit 500ff08b authored Oct 12, 2007 by Thomas Gleixner Committed by Thomas Gleixner Oct 12, 2007

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>

parent 80174097

arch/x86/kernel/apic_64.c

+0 −18

Original line number	Diff line number	Diff line
		@@ -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);

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