Commit 754ef0cd authored by Yasuaki Ishimatsu's avatar Yasuaki Ishimatsu Committed by H. Peter Anvin
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x86: fix debug message of CPU clock speed 



Impact: Fixes incorrect printk

LOCAL APIC is corrected by PM-Timer, when SMI occurred while LOCAL APIC is calibrated.
In this case, LOCAL APIC debug message(Boot with apic=debug) is displayed correctly,
however, CPU clock speed debug message is displayed wrongly .

When SMI occured on my machine, which has 1.6GHz CPU, CPU clock speed is displayed
3622.0205 MHz as follow.

	CPU0: Intel(R) Xeon(R) CPU            5110  @ 1.60GHz stepping 06
	Using local APIC timer interrupts.
	calibrating APIC timer ...
	... lapic delta = 3773130
	... PM timer delta = 812434
	APIC calibration not consistent with PM Timer: 226ms instead of 100ms
	APIC delta adjusted to PM-Timer: 1662420 (3773130)
	..... delta 1662420
	..... mult: 71411249
	..... calibration result: 265987
	..... CPU clock speed is 3622.0205 MHz.  =====>  here
	..... host bus clock speed is 265.0987 MHz.

This patch fixes to displaying CPU clock speed correctly as follow.

	CPU0: Intel(R) Xeon(R) CPU            5110  @ 1.60GHz stepping 06
	Using local APIC timer interrupts.
	calibrating APIC timer ...
	... lapic delta = 3773131
	... PM timer delta = 812434
	APIC calibration not consistent with PM Timer: 226ms instead of 100ms
	APIC delta adjusted to PM-Timer: 1662420 (3773131)
	TSC delta adjusted to PM-Timer: 159592409 (362220564)
	..... delta 1662420
	..... mult: 71411249
	..... calibration result: 265987
	..... CPU clock speed is 1595.0924 MHz.
	..... host bus clock speed is 265.0987 MHz.

Signed-off-by: default avatarYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 5ee81007

arch/x86/kernel/apic.c

+30 −17
Original line number Diff line number Diff line
@@ -535,7 +535,8 @@ static void __init lapic_cal_handler(struct clock_event_device *dev) 
	}

}



static int __init calibrate_by_pmtimer(long deltapm, long *delta)

static int __init

calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)

{

	const long pm_100ms = PMTMR_TICKS_PER_SEC / 10;

	const long pm_thresh = pm_100ms / 100;
@@ -557,18 +558,29 @@ static int __init calibrate_by_pmtimer(long deltapm, long *delta) 
	if (deltapm > (pm_100ms - pm_thresh) &&

	    deltapm < (pm_100ms + pm_thresh)) {

		apic_printk(APIC_VERBOSE, "... PM timer result ok\n");

	} else {

		return 0;

	}



	res = (((u64)deltapm) *  mult) >> 22;

	do_div(res, 1000000);

	pr_warning("APIC calibration not consistent "

			"with PM Timer: %ldms instead of 100ms\n",

			(long)res);

		   "with PM Timer: %ldms instead of 100ms\n",(long)res);



	/* Correct the lapic counter value */

	res = (((u64)(*delta)) * pm_100ms);

	do_div(res, deltapm);

	pr_info("APIC delta adjusted to PM-Timer: "

		"%lu (%ld)\n", (unsigned long)res, *delta);

	*delta = (long)res;



	/* Correct the tsc counter value */

	if (cpu_has_tsc) {

		res = (((u64)(*deltatsc)) * pm_100ms);

		do_div(res, deltapm);

		apic_printk(APIC_VERBOSE, "TSC delta adjusted to "

					  "PM-Timer: %lu (%ld) \n",

					(unsigned long)res, *deltatsc);

		*deltatsc = (long)res;

	}



	return 0;
@@ -579,7 +591,7 @@ static int __init calibrate_APIC_clock(void) 
	struct clock_event_device *levt = &__get_cpu_var(lapic_events);

	void (*real_handler)(struct clock_event_device *dev);

	unsigned long deltaj;

	long delta;

	long delta, deltatsc;

	int pm_referenced = 0;



	local_irq_disable();
@@ -609,9 +621,11 @@ static int __init calibrate_APIC_clock(void) 
	delta = lapic_cal_t1 - lapic_cal_t2;

	apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);



	deltatsc = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);



	/* we trust the PM based calibration if possible */

	pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,

					&delta);

					&delta, &deltatsc);



	/* Calculate the scaled math multiplication factor */

	lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
@@ -629,11 +643,10 @@ static int __init calibrate_APIC_clock(void) 
		    calibration_result);



	if (cpu_has_tsc) {

		delta = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);

		apic_printk(APIC_VERBOSE, "..... CPU clock speed is "

			    "%ld.%04ld MHz.\n",

			    (delta / LAPIC_CAL_LOOPS) / (1000000 / HZ),

			    (delta / LAPIC_CAL_LOOPS) % (1000000 / HZ));

			    (deltatsc / LAPIC_CAL_LOOPS) / (1000000 / HZ),

			    (deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ));

	}



	apic_printk(APIC_VERBOSE, "..... host bus clock speed is "

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