diff options
Diffstat (limited to 'drivers/pps/generators/pps_gen_parport.c')
| -rw-r--r-- | drivers/pps/generators/pps_gen_parport.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/pps/generators/pps_gen_parport.c b/drivers/pps/generators/pps_gen_parport.c index a15fe25efd55..5c32f8dacf56 100644 --- a/drivers/pps/generators/pps_gen_parport.c +++ b/drivers/pps/generators/pps_gen_parport.c @@ -76,8 +76,15 @@ static enum hrtimer_restart hrtimer_event(struct hrtimer *timer) long lim, delta; unsigned long flags; - /* NB: approx time with blocked interrupts = - send_delay + 3 * SAFETY_INTERVAL */ + /* We have to disable interrupts here. The idea is to prevent + * other interrupts on the same processor to introduce random + * lags while polling the clock. getnstimeofday() takes <1us on + * most machines while other interrupt handlers can take much + * more potentially. + * + * NB: approx time with blocked interrupts = + * send_delay + 3 * SAFETY_INTERVAL + */ local_irq_save(flags); /* first of all we get the time stamp... */ |