diff options
Diffstat (limited to 'arch/x86_64/kernel/time.c')
| -rw-r--r-- | arch/x86_64/kernel/time.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 9f05bc9b2dad..5cc76d0d331f 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -656,6 +656,25 @@ core_initcall(cpufreq_tsc); */ #define TICK_COUNT 100000000 +#define TICK_MIN 5000 + +/* + * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none + * occurs between the reads of the hpet & TSC. + */ +static void __init read_hpet_tsc(int *hpet, int *tsc) +{ + int tsc1, tsc2, hpet1; + + do { + tsc1 = get_cycles_sync(); + hpet1 = hpet_readl(HPET_COUNTER); + tsc2 = get_cycles_sync(); + } while (tsc2 - tsc1 > TICK_MIN); + *hpet = hpet1; + *tsc = tsc2; +} + static unsigned int __init hpet_calibrate_tsc(void) { @@ -666,13 +685,11 @@ static unsigned int __init hpet_calibrate_tsc(void) local_irq_save(flags); local_irq_disable(); - hpet_start = hpet_readl(HPET_COUNTER); - rdtscl(tsc_start); + read_hpet_tsc(&hpet_start, &tsc_start); do { local_irq_disable(); - hpet_now = hpet_readl(HPET_COUNTER); - tsc_now = get_cycles_sync(); + read_hpet_tsc(&hpet_now, &tsc_now); local_irq_restore(flags); } while ((tsc_now - tsc_start) < TICK_COUNT && (hpet_now - hpet_start) < TICK_COUNT); |