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| author | Dominik Brodowski <linux@dominikbrodowski.net> | 2008-09-05 14:05:35 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-09-06 15:33:33 +0200 |
| commit | 4ab6a219113197425ac112e35e1ec8062c69888e (patch) | |
| tree | dd5458a0dd70c00ef6ba171e7369148905f0b27c /drivers/clocksource | |
| parent | dfdf748a61a21b7397b9f57c83de722de71dc56a (diff) | |
| download | linux-4ab6a219113197425ac112e35e1ec8062c69888e.tar.gz linux-4ab6a219113197425ac112e35e1ec8062c69888e.tar.bz2 linux-4ab6a219113197425ac112e35e1ec8062c69888e.zip | |
clocksource, acpi_pm.c: check for monotonicity
The current check for monotonicity is way too weak: Andreas Mohr reports (
http://lkml.org/lkml/2008/8/10/77 ) that on one of his test systems the
current check only triggers in 50% of all cases, leading to catastrophic
timer behaviour. To fix this issue, expand the check for monotonicity by
doing ten consecutive tests instead of one.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/acpi_pm.c | 46 |
1 files changed, 29 insertions, 17 deletions
diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c index 860d033bc74f..4eee533f3f4a 100644 --- a/drivers/clocksource/acpi_pm.c +++ b/drivers/clocksource/acpi_pm.c @@ -21,6 +21,7 @@ #include <linux/errno.h> #include <linux/init.h> #include <linux/pci.h> +#include <linux/delay.h> #include <asm/io.h> /* @@ -175,10 +176,13 @@ static int verify_pmtmr_rate(void) #define verify_pmtmr_rate() (0) #endif +/* Number of monotonicity checks to perform during initialization */ +#define ACPI_PM_MONOTONICITY_CHECKS 10 + static int __init init_acpi_pm_clocksource(void) { cycle_t value1, value2; - unsigned int i; + unsigned int i, j, good = 0; if (!pmtmr_ioport) return -ENODEV; @@ -187,24 +191,32 @@ static int __init init_acpi_pm_clocksource(void) clocksource_acpi_pm.shift); /* "verify" this timing source: */ - value1 = clocksource_acpi_pm.read(); - for (i = 0; i < 10000; i++) { - value2 = clocksource_acpi_pm.read(); - if (value2 == value1) - continue; - if (value2 > value1) - goto pm_good; - if ((value2 < value1) && ((value2) < 0xFFF)) - goto pm_good; - printk(KERN_INFO "PM-Timer had inconsistent results:" - " 0x%#llx, 0x%#llx - aborting.\n", value1, value2); - return -EINVAL; + for (j = 0; j < ACPI_PM_MONOTONICITY_CHECKS; j++) { + value1 = clocksource_acpi_pm.read(); + for (i = 0; i < 10000; 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; } - printk(KERN_INFO "PM-Timer had no reasonable result:" - " 0x%#llx - aborting.\n", value1); - return -ENODEV; -pm_good: if (verify_pmtmr_rate() != 0) return -ENODEV; |