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Commit f1926ce6 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Ingo Molnar
Browse files

clocksource, acpi_pm.c: fix check for monotonicity 



Actually check the monotonicity of the ACPI PMTMR ten times, only delay for
0.9 miliseconds at most, and bail out early if some problem is determined.

Reported-by: default avatarJochen Voß <jochen.voss@googlemail.com>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6ef62164

drivers/clocksource/acpi_pm.c

+10 −11
Original line number Diff line number Diff line
@@ -178,11 +178,13 @@ static int verify_pmtmr_rate(void) 


/* Number of monotonicity checks to perform during initialization */

#define ACPI_PM_MONOTONICITY_CHECKS 10

/* Number of reads we try to get two different values */

#define ACPI_PM_READ_CHECKS 10000



static int __init init_acpi_pm_clocksource(void)

{

	cycle_t value1, value2;

	unsigned int i, j, good = 0;

	unsigned int i, j = 0;



	if (!pmtmr_ioport)

		return -ENODEV;
@@ -192,30 +194,27 @@ static int __init init_acpi_pm_clocksource(void) 


	/* "verify" this timing source: */

	for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) {

		udelay(100 * j);

		value1 = clocksource_acpi_pm.read();

		for (i = 0; i < 10000; i++) {

		for (i = 0; i < ACPI_PM_READ_CHECKS; i++) {

			value2 = clocksource_acpi_pm.read();

			if (value2 == value1)

				continue;

			if (value2 > value1)

				good++;

				break;

			if ((value2 < value1) && ((value2) < 0xFFF))

				good++;

				break;

			printk(KERN_INFO "PM-Timer had inconsistent results:"

			       " 0x%#llx, 0x%#llx - aborting.\n",

			       value1, value2);

			return -EINVAL;

		}

		udelay(300 * i);

	}



	if (good != ACPI_PM_MONOTONICITY_CHECKS) {

		if (i == ACPI_PM_READ_CHECKS) {

			printk(KERN_INFO "PM-Timer failed consistency check "

			       " (0x%#llx) - aborting.\n", value1);

			return -ENODEV;

		}

	}



	if (verify_pmtmr_rate() != 0)

		return -ENODEV;