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clocksource, acpi_pm.c: fix check for monotonicity

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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: Jochen Voß <jochen.voss@googlemail.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dominik Brodowski 2008-09-11 11:09:49 +02:00 committed by Ingo Molnar
parent 6ef62164e7
commit f1926ce63b
1 changed files with 10 additions and 11 deletions
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21
drivers/clocksource/acpi_pm.c
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@ -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;
@ -192,29 +194,26 @@ 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) {
printk(KERN_INFO "PM-Timer failed consistency check "
" (0x%#llx) - aborting.\n", value1);
return -ENODEV;
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)